I'm trying to engineer a gate but I'm not an engineer.

[zora]

It's a 30' span so I'll be building 2x 15' gates. They will never open and I'll build a pretty substantial sliding bolt to lock them together at the center. I plan on hanging them with 5" barrel hinges. The main structure of the gate will e 2x14ga square. I plan on making the checkerboard pattern out of 3/8 round and 16ga sheet. All hanging on 5x5x0.188 posts cemented 3feet in the ground. I figure the gates will weigh about 174# each as drawn.

I did the math (correctly, I hope) and calculated the required I needed for the posts. and came out just under the rated I for the posts. Ideally it would be better if I a bigger margin, But since the gates will never (rarely) open and will be secured together at the center I thought that it might be OK. I also will fill them concrete and rebar, but I have no idea what that will do to the strength of the post. I've explained all this to my client ( an old high school buddy, so he knows what we're getting into)

My biggest concern now is whether or not the gates will hold their shape. I plan on using some 2x0.25 tubing for the outside edges to support the hinges, but other than that I am utterly lost. I don't know if the checkerboard will provide enough support. I can use bigger rod but I have literally tons of 3/8 lying around that I'd like to use up. I was trying to stay away from diagonal members, because of weight and aesthetics, but I could "hide" them behind the checkerboard if I went to a 1.5 tubing for them.

Do you think that they will hold their shape? What kind of strength will I gain by filling the posts with concrete? How big of a gap should I leave at the center where the 2 gates meet? Is it even heavy enough to matter? Should I hire an engineer?

I have lots of questions I don't want to waste your time with, but I'd appreciate any thoughts or advice you might have. Also is there any particular book you could recommend for problems like this.

Thanks

[DSW]

How about adding a wheel or wheels for added support since it's on blacktop? Someone here posted up a nice setup for a self adjusting gate wheel for a large gate not too far back. Also you might consider a leg/ locking bolt that goes into the blacktop since you don't need to open it frequently. You could still use a wheel in the center as support, and then use the leg to both support and lock the end where the gates meet.

[mrmikey]

I'd say it's going to bow down. Run a diagonal piece of bar from the top left to the lower right, so it's in tension. Doesn't have to be anything extremely large since it'll be in tension, 1/2" sq or round bar.
I's go with a 2" gap at least.
I's definetly go with some sort of support on the ends like DSW suggested. that's a lot of leaverage since it's such an overhang. The posts on each end are going to have to be quite substantial and well anchored.....Mike

[CurreyR]

how about doing the checkerboard on a 45? The triangulation would then almost behave as a truss to help it hold the rectangular shape.

[Fegenbush]

I sent you a PM with my contact info if you want to discuss the project. No charge on engineering, just looking to build my portfolio.

[Broccoli1]

Are you building a fence as well?

Seems kinda strange to build a gate and have the Sides open where the grass is.

Oh.. and 16g is pretty thick for the panels.

[nearbeer]

+1 what DSW said. Wheels will reduce the bending moment at the top of the concrete post; this will help keep said post vertical as time goes by.

/R,

NearBeer:drinkup:

[Fegenbush]

Could you run a turnbuckle setup from the bottom inner to the top outer corner. That would stiffen it up quite a bit. It shouldn't take any more than 3/8" rod to do that, either.

At the current weight, you're only looking at 750 lbs pushing/pulling on the hinges, so I don't think that's excessive. Wheels will negate this altogether (almost). However, if you use 24 gauge instead of 16 gauge, you'll lessen it even more.

[zora]

How about adding a wheel or wheels for added support since it's on blacktop? Someone here posted up a nice setup for a self adjusting gate wheel for a large gate not too far back. Also you might consider a leg/ locking bolt that goes into the blacktop since you don't need to open it frequently. You could still use a wheel in the center as support, and then use the leg to both support and lock the end where the gates meet.
I thought about that, but the ground is sloped in 2 directions and I would have to allow the wheel to travel ~18 inches up and down. (another can of worms :))

how about doing the checkerboard on a 45? The triangulation would then almost behave as a truss to help it hold the rectangular shape.
Would be cool (and strong), but the parking lot is for a lube shop and checkerboard flags are their logo.

I sent you a PM with my contact info if you want to discuss the project. No charge on engineering, just looking to build my portfolio.

thanks.

Are you building a fence as well?

Seems kinda strange to build a gate and have the Sides open where the grass is.

Oh.. and 16g is pretty thick for the panels.

No fence, Only to keep cars from cutting across his parking lot.

It's funny you say that 16ga is heavy. My first design was to use 1/4" plate. (they were burnouts from something and I got a great deal on them and they were already cut:drinkup:) I was gonna build the whole thing out of 2.5x11ga tubing too, but the gates came in at about 500lbs each . I figured it would take a 7x7x0.188 steel post to carry it :dizzy:



I's go with a 2" gap at least.


2in? I was planning a 3/4" gap (and thought that might be too big) Why so much?


I'll probably build it next week, I'll put in some diagonals and I'll let you all know how it turns out.

[Boostinjdm]

Make the posts at least a 1/4" thick to account for rust down the road.

[mrmikey]

2in? I was planning a 3/4" gap (and thought that might be too big) Why so much?
Things are gonna move I'd bet on it. A far site easier to close up a gap with a filler piece than try and open it up.....Mike

[madkaw284]

Id go with the turn buckle corner to corner like previously mentioned, a 2" gap is huge, there's no reason it needs to be that big, it would make it look like you didn't measure correctly and everybody that passes by would say to themselves "holy s**t, who built and designed this bad fit up". I ALWAYS take into consideration what people will think when they look at a finished project of mine and weather or not i would want my name on it, but im an extremely self proclaimed perfectionist as i'm sure most on here are. Also to support the mounting posts (From deflection) could you support them on 3 sides or at-least 1 with with steel cable ,or whatever material you can use, mounted at or toward the top and anchor them into the ground or would that be an issue? I dont know, Im sure you'll get it all figured out. Good luck, keep us posted.

[madkaw284]

Oh, I see you have a sidewalk there so maybe one side to pull back if you can, and definately lighter guage sheet

[steve45]

I'm an engineer, but I haven't done any calculations on this (and really don't have time to). Just by looking at it, and driving through gates every day that are made of 2-3/8" round tubing, I'd say it will sag. The gates I typically see are a simple triangle, with a horizontal pipe and a diagonal that goes about 2/3 of the way from the bottom hinge to the horizontal top piece. These are much lighter than your design and they sag.

Yours will deform at the square pattern pieces, mostly close to the hinge.

I'd suggest a wheel, as well as a diagonal support. I think your hinges are way undersized, too, but may work if you don't open the gave very often. Most of the gates I see are hinged by means of a pipe within a pipe (2-3/8" and 2-7/8") with some grease fittings.

As far as the posts, how firm is your ground? We have very dry, hard ground/rock in my area and most heavy gates have a tall posts with a crossbeam to keep the posts from moving.

[oxygen454]

I have build a few gates in the past and I totally agree with the above, there is going to be some major sagging going on. You need to do one of the following, cross bracing, wheel or even make two gates.

At 181" or 15', there is going to be a lot off stress and weight that far out from your hinge point. This is based on the theory of leverage.
I would use 16ga. my self but with a bit of a different design. 100 wall square tube can be used to keep the weight down. Go to google images and take a look around.

For hinges, I have used 1" round stock with a 1"DOM round tube with a grease fitting in the side of the DOM. Problem with no the grease is, water can get causing rust which can lock up the hinges.

Figure out the weight of the material used to make the gate inducing your checkers. Major steel suppliers have the data of weight per foot. This will give you an idea of how much weight will be swinging back and forth.

[oxygen454]

Here is one idea that can be modified to your liking. The checkers cans till be put on the front side.

[tapwelder]

Here is a cantilever gate did with 18 feet stick out. It does have a catch at the end, however I does not have to be raised up to align.

http://weldingweb.com/showthread.php?t=20699&highlight=sliding+gate

If you are concerned about sag. Will people sit it.

Then, perhaps add a short gusset underneath about half way out or less on your design.

or since it will rarely open how about an adjustable/removable leg or wheel( as suggested) in the middle.

or if you have the space how about cantilever system.

[dave powelson]

Zora---some guys talk about making gates...some guys actually
make gates....and a few guys make gates that are square, plumb,
don't sag, are run by power operators and actually stand the test of time.
Many guys that "do gates" are crude hacks.

On your project--going the cantilevered way as oxygen454's picture shows would be
practical.
Your concept drawing, won't hack it for a whole bunch of reasons, as it's drawn.

With a diagonal brace-as I've shown.....it's a maybe--for 15',
everything dependent on just how technical a job you really can do.

The suggestions of a gypo, turnbuckle cable or rod---don't cut it.
That's what the hacks do--and they don't even get that part of the fab
or design done right.

(Post-fab, stressing to counter sagging--which would induce some
bowing is another item I might consider....if doing this myself....but
that's not for the faint of heart or weak of mind.)

You don't note what size of pipe you intend on using. Size counts.
Using the hinge post as the inner pin--works and can be very stout
way of creating a great hinge. Hinges either make or break a gate..
....but the hacks pick the weakest hinges, everytime. I've made bux,
fixing others 'gate jobs'--a real learning experience.

Selecting a close or tight fit with corresponding ID/OD's of S.40, S.80
you can create the basis for the hinge assembly. These hinges
were sanded, polished and sized for .020--total inside clearance;
which on a 'big' hinge is zip (not sloppy). The clearance is taken up
by the injected grease, which also stops corrosion, plus the graphite
spray.


The posts will need to be embedded with steel embedment in concrete,
in rather substantial holes.

If I was doing this--it would be steel embed in the concrete, with J bolts coming up,
for leveling nuts under separate hinge post foot plates---that just makes the embed and the
final field install--a snap.
....If the gate hinge posts are bolted to the embed--WHEN--not if---the gates are hit,
it can make repair much more do-able.
Pre-fit, pre-hang the gates, hinge barrels and hinge post in the shop--for accurate
job and no field install hassle.

On any gate--the bottom hinge should take all the gate weight, the top hinge
only locates---this reduces stress on the gate and the post

14' swing gate that doesn't sag. Gate was square prior to mounting,
measured level and plumb--after mounting. Gate weight-253#
all powdercoated-with weep drain holes, pre-drilled bolt holes
for accessories, etc.

2 x 2 x .25 wall for gate hinge barrel mount side
2 x 2 x .120 wall for the rest, mitered, bevel groove welded corners
-----all tube weld seams in line and on the inside periphery (which helps
to control distortion and increase stiffness....
1 x 1 x .065 pickets fully welded-in fixture

2 1/2" pipe for inner bearing-sized, sanded, polished
3" pipe for outer bearing--sized, sanded, polished

UHMW thrust washers, graphite sprayed, multiple grease
fittings--for the hinge assemblies. Top and bottom hinge barrels
were actually lined up in the field with 5', sanded, alignment pipe--
since there was a bunch of field adjustments made via bolting in machined
slots of the top and bottom hinge mounts.
Many 'gate guys' never check or worry hinge alignment.

[Customer insisted on using the 2 outside 12" poles for the gate mounts--the other side is a
4' man gate. I did so--after written agreement that whatever happened to the wood poles
was his responsibility, that I did not agree.]

http://weldingweb.com/attachment.php?attachmentid=59876&stc=1&d=1292921725

http://weldingweb.com/attachment.php?attachmentid=59877&stc=1&d=1292921743

[zora]

For hinges, I have used 1" round stock with a 1"DOM round tube with a grease fitting in the side of the DOM. Problem with no the grease is, water can get causing rust which can lock up the hinges.
.

Yeah, the consensus is bigger hinges. What size DOM did you use. It would be super conveinient if I could use some 1-1/4 OD x .120 wall x 1.01 ID So I could buy a stick and use it for some other projects I have but I'm concerned .120 isn't big enough.


Here is a cantilever gate did with 18 feet stick out. It does have a catch at the end, however I does not have to be raised up to align.

http://weldingweb.com/showthread.php?t=20699&highlight=sliding+gate

If you are concerned about sag. Will people sit it.

That's a nice gate there. I was reading your original post and totally understand the "overwhelming" part. If I had the space I think that I would built a cantilever design.

Yes, people will probably sit on it.


With a diagonal brace-as I've shown.....it's a maybe--for 15',
everything dependent on just how technical a job you really can do.

The suggestions of a gypo, turnbuckle cable or rod---don't cut it.
That's what the hacks do--and they don't even get that part of the fab
or design done right.

The posts will need to be embedded with steel embedment in concrete,
in rather substantial holes.
http://weldingweb.com/attachment.php?attachmentid=59876&stc=1&d=1292921725

http://weldingweb.com/attachment.php?attachmentid=59877&stc=1&d=1292921743

Very Nice. I think that I'm going to steal some of your design. Simple, and the vertical pickets would provide a nice framework for my "checkerboard" pattern.

I dig your hinges, but since my gate will never open, They would probably be overkill.

I will probably go will a wheel though. I don't want to, but I've already set the posts, and I fear that they are not strong enough , or set in enough concrete to support it. (5x5x.188 in 10" holes 36" deep)



Everyone here is amazing. You have saved me countless tears and for that I thank you. Back to the drawing board...

[MickLA]

For your posts- Shouldve gone with 1/4 but concrete and rebar will strengthen perfectly fine. A good practice is what is called a ground kit.
Ground kit- anchor (dry pins are fine) a 1/8 or so piece of angle to the driveway just below the level of the driveway, then weld one piece of 1" square tubing in whatever size you have handy perpindicular to the driveway, and another piece at about a 45-60 degree angle in the direction the gate will open. This will stiffen the post immensely as it will also push against all the driveway concrete, at least at the base, where most post bending occurs anyways.
Hinges- I would recommend using hinges that bolt through the post, so that when the gates sag slightly you can adjust them back up with only a crescent wrench, which im sure your buddy has handy. Blacksmith Brand from Triple S steel are pretty well made and reasonably priced
You actually dont need to use thicker steel for the frame than youre using for the interior, alot of gates made of 14 ga square tubing in that size hold up perfectly well, and that will save you alot of weight. The hinge pull is more of a sideways force than a vertical one, and 2" square in 14 ga can hold alot of weight in that direction. Going thinner than 16 ga on your panels will work but keep in mind the thinner it is the harder its going to be to stop it from warping when you get to welding it.
If you run a piece of your 3/8 round from your upper corner downhill to your lower one, in the direction of the weight, you will stop alot of sag in the gate. Ive seen an 18 ft gate with 4 inch center 1/2 inch pickets with a bell curve top, a one piece gate, sag only 1/8 of an inch upon hanging with this kind of round bar installed, so you should be able to adjust the sag back out when youre hanging if you use bolt-through hinges.
A tip- not everybody will agree with this, but you will save yourself alot of trouble if you clamp the gates together and hang them as one piece, instead of hanging them one at a time. It is very difficult to hang gates one at a time and have the tops line up. Tack the bottom hinge at first then swing the gates, and if they dont have enough ground clearance, insert a half inch piece at the bottom hinge, then level back up. This will cause the gate to rise as it is opened. Good luck

[MickLA]

For your posts- Shouldve gone with 1/4 but concrete and rebar will strengthen perfectly fine. A good practice is what is called a ground kit.
Ground kit- anchor (dry pins are fine) a 1/8 or so piece of angle to the driveway just below the level of the driveway, then weld one piece of 1" square tubing in whatever size you have handy perpindicular to the driveway, and another piece at about a 45-60 degree angle in the direction the gate will open. This will stiffen the post immensely as it will also push against all the driveway concrete, at least at the base, where most post bending occurs anyways.
Hinges- I would recommend using hinges that bolt through the post, so that when the gates sag slightly you can adjust them back up with only a crescent wrench, which im sure your buddy has handy. Blacksmith Brand from Triple S steel are pretty well made and reasonably priced
You actually dont need to use thicker steel for the frame than youre using for the interior, alot of gates made of 14 ga square tubing in that size hold up perfectly well, and that will save you alot of weight. The hinge pull is more of a sideways force than a vertical one, and 2" square in 14 ga can hold alot of weight in that direction. Going thinner than 16 ga on your panels will work but keep in mind the thinner it is the harder its going to be to stop it from warping when you get to welding it.
If you run a piece of your 3/8 round from your upper corner downhill to your lower one, in the direction of the weight, you will stop alot of sag in the gate. Ive seen an 18 ft gate with 4 inch center 1/2 inch pickets with a bell curve top, a one piece gate, sag only 1/8 of an inch upon hanging with this kind of round bar installed, so you should be able to adjust the sag back out when youre hanging if you use bolt-through hinges.
A tip- not everybody will agree with this, but you will save yourself alot of trouble if you clamp the gates together and hang them as one piece, instead of hanging them one at a time. It is very difficult to hang gates one at a time and have the tops line up. Tack the bottom hinge at first then swing the gates, and if they dont have enough ground clearance, insert a half inch piece at the bottom hinge, then level back up. This will cause the gate to rise as it is opened. Good luck

[fortyonethirty]

Your gate design will not sag. You have plenty of diagonals (see picture). Your selections all seem reasonable, except I would drop the perimeter tube to 2x2x.120 to save some weight. Stick to the 16 ga. panels as they will be stressed (see picture) and they are easier to weld than anything thinner.

Your post selection is fine. You need to worry about the ground supporting the posts. They will sag over time. The easiest way to prevent this is to take the weight off of the posts when the gates are shut. Cane bolts can be used for this purpose.

A larger gap in the center will hide a small amount of misalignment. Nobody is perfect. 2" sounds about right.

A sliding bolt will be very difficult to align properly. Again, use cane bolts instead.



Dave Powelson's gate is the most over built gate I have ever seen, wow.

[oxygen454]

Daves gate looks great. You say its over kill, maybe, but it will stand up to the test of time. Looks clean and totally like those hinges.

I agree the sliding bolt would be hard to line up. After break-in, use, and ground settling, you might find the bolt wont line up and will probably need constant adjustment.

As a side note, the perimeter tube should be strong enough to hold up but not too heavy. For example, you could make it 1/2 thick square tube which is total overkill. It will still bend and will add a ton of weight. I would use something near 1/8 (.125).

The last couple of gates I have made, I used threaded rod to adjust the gates swing height. Many different ways of building a gate :)

[weldingguru00]

The design looks functional but may come across as eyesore. Maybe worry about how it looks too.

[engineer1984]

Dave,

is that gate supported on the 'open' side at all? I really like that, nice job.

[dave powelson]

*****Sorry for the delayed response-I tried to edit my email address
in WeldingWeb profile and have been stuck in a one-way, Logic Trap--
for a week-not being able to post, and getting NO HELP from contacting
the WeldingWeb, webmaster.

1-Overkill?

-gates, post and hinge assemblies have to be extremely stiff in
torsion, bending, etc.---especially if used with way to light of a power operator
(which the owner had and installed--despite my warning that it was a flimsy
power operator). Wind load and gate inertia can wreck an operator and/or
its mounting....usually the mountings are inadequate, anyway.

-This gate also has a power operated latch on the man gate post--
requiring a stiff gate, to maintain alignment

-This gate assembly has now been in service- 5 1/2 years--with a happy
owner.

2-What hasn't been mentioned (or apparently realized) in the banter
about Zora's proposed design:

-the construction methods--if simply welding in diagonals--will produce
significant distortion, which can be minimized via doubler plates and other
forms of pre-stressing the frame to counter weld distortion.

3-engineer1984 asks:

is that gate supported on the 'open' side at all? I really like that, nice job.

-Thanks for the compliment.
-No, the gate is not supported on the open side. It's a swinging gate that
latches into the power latch on the man gate post.

-Despite the weight of the gate and resulting inertia at 14'......it would move
thru it's swing with a push of several pounds....and it was set plumb,
level, with the top and bottom hinge barrels forced into alignment via
a 5' alignment pipe as noted above.
(The upper hinge barrel assembly was fit and welded with .010 brass shimming
around an alignment pipe--to have both of those barrels in line with each other.
This was done in the shop, prior to p-coat and install.
....ditto for aligning the gate frame hinge barrels--it's done in the shop.)

Using a top hinge that is double shear design, makes it close to indestructible.

I won't use the big square block with big round pin hinges--that can and will
bend and are sorely over-rated (since they're 'single shear' design)......like many 'gate guys' do.

[steve45]

After looking at this again, I think that the original design will be so heavy that it may not sag, but buckle near the hinge.

[zora]

1-Overkill?

(The upper hinge barrel assembly was fit and welded with .010 brass shimming
around an alignment pipe--to have both of those barrels in line with each other.
This was done in the shop, prior to p-coat and install.
....ditto for aligning the gate frame hinge barrels--it's done in the shop.)

Using a top hinge that is double shear design, makes it close to indestructible.

I won't use the big square block with big round pin hinges--that can and will
bend and are sorely over-rated (since they're 'single shear' design)......like many 'gate guys' do.
I really didn't mean overkill. Those are gorgeous hinges, and if I had the budget, tools, or the talent to make them, believe me, I would. (I asked santa for a lathe though, maybe next year:))

However, with those limitations I did pick up some ' 1.5x.120 DOM with some 1.25 CR round to build my hinges with. My thoughts were that it would give me a .010 gap and with some zerks and limited use, I should be OK. (plus I'll have lots left over so I can get to work on my ring roller I'm trying to build:drinkup:)

Thanks for the double shear advice. I'll take it! Lemme give it some thought. Any other words for a guy who has never built a hinge before.

After looking at this again, I think that the original design will be so heavy that it may not sag, but buckle near the hinge.

thanks, am working on a different design. I'm more of an artist than a welder, and sometimes I imagine things in my mind that just won't work. :dizzy: Though, with experience I'm hoping that it will get better.

A gate sounds simple enough, but I've never really appreciated everything that goes into building one until now.

[oxygen454]

Think of bridges and roof trusses which span long distances. Also we know that triangles are on of the strongest designs known to man. Cross bracing forms triangles and offers a large amount of strength.

It may not work out quite as your original plan for visual cosmetics but its better looking than a sagging gate. I think you get the point. I think we beat the sagging to death. LOL

Basically to sum it up. Think of larger objects or similar to what your building and determine what keeps them from deforming or collapsing.

[fortyonethirty]

Dave Powelson, on the gate you posted, why is the top hinge made different from the bottom hinge?

[dave powelson]

Dave Powelson, on the gate you posted, why is the top hinge made different from the bottom hinge?

The top hinge pin rotates inside both barrels.
The 2 barrels effectively place the hinge pin, rotating as the gate
swings into 'double shear' form of stress loading.

A single barrel will allow easy bending and distortion of the pin, pin mount
and/or the single hinge barrel. (The "2000#", etc. block and pin hinges
can have the pins-even big diameter ones-bent, pretty easily--since they're
single-shear......been there-once and dun that.....that's 'why??' the double
shear.)
The double prevents this.
All of the gate downwards weight is carried by the lower hinge,and that hinge
pin rotates with the gate inside the lower barrel, which has a UHMW thrust
washer to carry the gate weight.
The upper locates the top of the gate.

As mentioned prior-this has now been in service 5 1/2 years.
"If you think-size doesn't count.....You can't count!"....John Holmes

[fortyonethirty]

I guess I should have asked, why no double shear on the bottom?

[dave powelson]

I guess I should have asked, why no double shear on the bottom?

That's actually a thoughtful, studied question!
It just earned you a gold star! :)

The top hinge locates/positions the top. That's the hinge that really
takes the gaff of side thrust.

The lower pin has 2 diameters of pin supported by that lower pin barrel
to support it.
It sees a fraction of the side thrust forces that the upper hinge does.

In a 'normal' gate/post arrangement--I would have gone with smaller
dia. hinge sets and the double shear on top and bottom.

This was a highly abnormal deal--using those not-plumb 12" power poles
as the hinge posts--which I (and every other fabricator contacted)--objected to.

......That being the case--I wanted the weight of lower hinge and parent hinge alignment
'C' channel, to rest and be anchored the existing concrete pour around the wood post.

(There's no way I wanted to hang that weight on the wood post-itself. The wood post
simply locates the 'C' channel--which still imparts all the thrust to the pole.
Channel is fixed to the post via 3-7/8" OD B7 threaded rod in thru holes bored in the poles.)

Pic below shows adjustment slots for top and bottom barrel lineup, for the field fit and
to compensate for the known out of plumb pole condition
and holes for the concrete anchors. (The lower barrel was welded to the gate frame, along
with the upper barrel, using the lineup pipe thru both, with clearance shims.....prior to powdercoat
and field install.)

http://weldingweb.com/attachment.php?attachmentid=60721&stc=1&d=1294113457

[oxygen454]

Now thats what I call a hinge!! Holly crap thats beefy and nice!. UHMW washer for wear too! Nice!! :drinkup:

[fortyonethirty]

"It (lower hinge) sees a fraction of the side thrust forces that the upper hinge does."

Why is that?

[oxygen454]

I would think the reason is because the weight hangs off the top more than the bottom. The gate would pull on the top hinge and the bottom takes up the rest of the weight and alignment.

Also when pushed open, the force is normally applied over half way up unless the gate is really tall.

Thats what I have found when building gates. The top hinge seems to fail first.

[dave powelson]

"It (lower hinge) sees a fraction of the side thrust forces that the upper hinge does."

Why is that?

The basic weight of that gate is transmitted thru the lower hinge-not the upper.
Think of it as a pivot point-in this case, fastened to the very base of the pole, via
bolting and the concrete anchors.

The upper hinge locates and receives much of the leveraged (vectored) forces
from the gate's length, plus it's 4' above the fixed pivot point.
All of that force has to be absorbed and transmitted
thru the C channel and the pole--4' away from that fixed, rather rigid, base pivot point--
--the lower hinge pin.

On big or small gates, even with leaf hinges--I'll clearance the leaf hinges, weld the knuckles,
ream for slip pin bolts and set the hinges so the lower hinge takes the down-thrust weight of
the gate---while the upper hinge 'floats'. That double shear, upper hinge is set in a floating mode,
even though that's not apparent.

The idea of all of the above--being to minimize the deflection forces on that top hinge
and the hinge post--by making the lower one carry the basic gate weight.
(The top hinge in any gate, has all it can do-to deal with forces, without adding the
gate's weight to the equation. Ditto for the gate post.)

The higher the deflection forces are (like having the top hinge carry gate weight-too),
the more deflection in the gate post--which is 4-5-6' --whatever, above ground level.
Increase the deflection forces unnecessarily in that top hinge and you increase
top hinge and hinge post problems.

[dave powelson]

I would think the reason is because the weight hangs off the top more than the bottom. The gate would pull on the top hinge and the bottom takes up the rest of the weight and alignment.

Also when pushed open, the force is normally applied over half way up unless the gate is really tall.

Thats what I have found when building gates. The top hinge seems to fail first.

Oxygen454 sez:

"Thats what I have found when building gates. The top hinge seems to fail first"

Dave sez:

"Me-too!"

[Brett]

[QUOTE=
This was a highly abnormal deal--using those not-plumb 12" power poles
as the hinge posts--which I (and every other fabricator contacted)--objected to.

QUOTE]


Hey Dave , long time no talk.

I personally had reservations on the wisdom of hingeing to a Power Pole also, doubt if it would be legal over here,
5 1/2 years , has the pole moved at all so as to need any adjusting?
Love the size counts quote :)

Brett

[Brett]

Oh and another thing, Dave when I first saw your gate I thought to myself

"mmm , rather than 1 brace I'd go 2 or 4 "
So as to make it a parallel chord truss set up.
But you said 5 1/2 years , well the proof is in the pudding as they say.
There must be many instances where we often over engineer , purely from a point of view that , "Well I know this works..... " Not willing to change in fear of the job not performing and not wanting to put our clients in that situation either.

Brett Thompson

[joiseystud]

"It (lower hinge) sees a fraction of the side thrust forces that the upper hinge does."

Why is that?

SInce the distance from the axis of rotation is greater at the top hinge there is mechanical advantage. So if we applied 10 pounds of force to the top hinge and it was 5 feet from the axis of rotation, it would 50 foot pounds of torque. At hinge B it would be 1 foot away with the same 10 pound force would only be 10 foot pounds of torque.

THing is that torque is at the axis of rotation, not the hinge, so I dont see why the top hing itself would take more force unless the hinge itself was the axis of rotation (which is dave's design against the pole. I would try to avoid having your hinge be the axis of rotation unless there is a real need like Dave's and in that case the hinge has to take all of those loads.

Keep in mind I am no structural engineer, just remembering some basic physics about moments of force so if someone else has a better explanation I would be interested in the math.

60737

[joiseystud]

I can see that my approach was incorrect because the assumption was equal force at the two points. I think this explains the issue better since the force is actually the downward force against the gate.

60738

[fortyonethirty]

Joiseystud, "I can see that my approach was incorrect because the assumption was equal force at the two points. I think this explains the issue better since the force is actually the downward force against the gate."

Your first assuption was right.


There are two points holding the gate.

They are parrellel to the force acting on the gate.

How could the force acting on the two points be different?

The only difference is the direction. The top hinge pulls out, the bottom hinge gets pushed into the post.

Your drawing shows the moment at the bottom of the post, not the hinges, if you redraw it showing the moments pivoting at the hinges, you'll see that they could not be different.


I'm not saying that the top hinge won't wear out quicker, i'm saying that it's not because the force is greater, it's got to be something else.

[dave powelson]

[QUOTE=
This was a highly abnormal deal--using those not-plumb 12" power poles
as the hinge posts--which I (and every other fabricator contacted)--objected to.

QUOTE]


Hey Dave , long time no talk.

I personally had reservations on the wisdom of hingeing to a Power Pole also, doubt if it would be legal over here,
5 1/2 years , has the pole moved at all so as to need any adjusting?
Love the size counts quote :)

Brett

YO! Brett!---good to hear from you, too!

1-The poles are treated power poles--but don't function as power poles.
Messing with a power pole, I'd suspect in CA is a felony + gross stupidity.

2-The 14' length is 3.5 X the height (4').
Get in the neighborhood of 4X height and deflection issues become dicey
without additional triangulation--let alone the ramped up inertia of a long
gate swinging.

The fully welded center pickets add stiffness to the frame, and the frame weld seams face inwards on all four sides. (Pickets were sequentially tacked and
welded to counteract weld distortion of the frame--it stayed square within
+/- 1/16" on outside diagonal measurement)
Positioning of the weld seam can add or subtract from weld distortion
and frame stiffness.
After fully welding the pickets, prior to installing the 30 degree brace--I
blocked the frame, then tried to spring it with leveraged force.
It appeared to me-that this frame was stiff enough, not to require that brace.
Installed it anyway, since it would help stiffen the frame from side deflection,
was part of the design plan, etc.

Massive, redundant triangulation on a gate--adds big time to gate
inertia when swinging--and that tears up lots of gates, posts, hinges
and power operators.

As far as I know--via the owner, the gate functions as installed.

4130 & Joiseystud:

1-consider the lower hinge as a fixed or 'zero' point, the upper is 4' away
and sees leveraged forces that the lower hinge does not.

2-Embracing concept 1-above--that's 'why' deflection and deformation forces
really work on the top hinge and the hinge post.

Everything-deflects and deforms--either elastic (temporary)
.... or plastic (permanent). The idea is to keep things in the low end range of elastic deformation.

[fortyonethirty]

"1-consider the lower hinge as a fixed or 'zero' point,"

That's a lot like what I said. But, you seem to be ignoring the other half. All forces in a static object have to cancel.

" the upper is 4' away and sees leveraged forces that the lower hinge does not."

If by that, you mean that they are equal and in the opposite direction, you're right.

[joiseystud]

Joiseystud, "I can see that my approach was incorrect because the assumption was equal force at the two points. I think this explains the issue better since the force is actually the downward force against the gate."

Your first assuption was right.

There are two points holding the gate.

They are parrellel to the force acting on the gate.

How could the force acting on the two points be different?

The only difference is the direction. The top hinge pulls out, the bottom hinge gets pushed into the postYour drawing shows the moment at the bottom of the post, not the hinges, if you redraw it showing the moments pivoting at the hinges, you'll see that they could not be different.


I'm not saying that the top hinge won't wear out quicker, i'm saying that it's not because the force is greater, it's got to be something else.




Yes. It seems that the force would not be a moment because the two connection points dont allow a rotation. I think the forces would like you said a pull at the top hinge and a pull at the bottom. They should be equal although one in tension and one in compression. Right?

[joiseystud]

[quote=Brett;455764]


4130 & Joiseystud:

1-consider the lower hinge as a fixed or 'zero' point, the upper is 4' away
and sees leveraged forces that the lower hinge does not.


Is ONLY the lower hinge a fixed point? I think this would be treated as two fixed points.

2-Embracing concept 1-above--that's 'why' deflection and deformation forces
really work on the top hinge and the hinge post.

I agree the forces would be different on the two hinges, but i think they would be tensile against the top hinge and compressive against the bottom. Maybe the hinges are just better with compressive lateral forces?

[steve45]

The horizontal forces on both hinges would be equal, only in opposite directions.

A moment is force x length, it doesn't require or imply rotation. A moment applied to a body can be applied anywhere with the same result.

[joiseystud]

Thanks steve45. I dont suppose you could show the freebody diagram of this scenario? Thanks in advance.

[Brett]

Dave both hinges will have equal and opposite horizontal load.
The vertical load distribution will depend on how they were built. There could be a considerable difference between the vertical load on the two hinges. You could have all the vertical load on the top hinge, and the bottom hinge only providing horizontal restraint.
I can see advantages of a "Double" pin like your top one but those advantages apply to the bottom one also and are ,to my way of thinking largely negated if you dont use top and bottom.


Still :If it aint broke...dont fix it " :)

Keep posting your work it great.

Brett

[Brett]

"Keep posting your work it great."

LOL mmm Ugg me strong like moose , smart like truck

:)

[dave powelson]

Fixating on just a 2 plane, static view of the hinge forces being equal is correct...
...as far as that goes. Swing gate are dynamic animals.

Folks need to consider the hinge post and how it comes into play.

What's apparently not realized is that the hinge post--will deflect.

When that pole deflects--the upper hinge location will move more than the lower hinge,
inducing more stress in the upper hinge than the lower, which has not moved as much. As this either elastic or plastic deformation occurs, the
centerlines of the top and bottom hinges are no longer in the same planes,
with the top hinge seeing significantly more stressing from this centerline
offsetting than the bottom hinge--the hinges are binding up.

It's this deflection of the post that tears up lots of hinge arrangements, often accompanied by
the hinges never been aligned in the first place.

Reducing post deflection by having the lower hinge carry all of the gate's vertical component, helps a bunch. This repeated tidbit, apparently is not understood.
"Everything-deflects and deforms--either elastic (temporary)
.... or plastic (permanent). The idea is to keep things in the low end range of elastic deformation."


Brett--the lower hinge with it's 2+ dia. of pin support, nested inside double
3/8" plates--I judged to be stout enough to take the gaff, instead of
the double shear since "There's no way I wanted to hang that weight on the wood post-itself....
...That being the case--I wanted the weight of lower hinge and parent hinge alignment 'C' channel, to rest and be anchored the existing concrete pour around the wood post."

The upper hinge simply floats, the lower takes all of the gate's vertical load.
Knowing that out-of-plumb pole would require the lower hinge to be field aligned and adjusted with the upper to make the hinge centerlines plumb and common to each other--
that's 'why' the slotted shear bolts thru the double plates and 'why' I was not going to do the hassle of creating a double shear hinge set for the lower, that could be adjusted and rigidly fixed-- spanning a 1" travel to get things lined up.

"In a 'normal' gate/post arrangement--I would have gone with smaller
dia. hinge sets and the double shear on top and bottom."

[Donald Branscom]

For every foot out that a beam(gate) sticks out from its attaching pivot any load on the gate including its own weight is multiplied times 1000 on that attachment point.


So if someone sits ,stands or climbs over the gate, that force is multipied times 1000 at the distance they are from the pivot point.

[denrep]

. . .any load on the gate including its own weight is multiplied times 1000 on that attachment point.
So if someone sits ,stands or climbs over the gate, that force is multipied times 1000 at the distance they are from the pivot point.

I understand the theory, calculating a lever with a fulcrum point located with a distance of almost zero from the load. However, 200 lbs at 10' is not going to exert 200,000 lbs, or 100 tons, on the gate's attachment point.

Good Luck

[SundownIII]

Another one of Donald's totally inaccurate statements.

This guy sure "throws out" a lot of BS with nothing to back it up.

Oh, and Donald. Yes I am an engineer (Civil and Industrial) and got a couple degrees to back it up. Also registered as a PE in four states.

[Tom17]

When that pole deflects--the upper hinge location will move more than the lower hinge, inducing more stress in the upper hinge than the lower, which has not moved as much.

I don't want to argue with your design, I think it's a great looking gate, but I disagree with this statement. The horizontal force is equal but in opposite directions on the upper and lower hinge points, a fact that had previously been mentioned. As a typical post is anchored at the bottom and usually non-anchored at the top, then it acts as a lever with the base of the post acting as its fulcrum. As such, a force of x applied at the hinge at the non-anchored end will apply a far greater moment than the opposing moment derived from the force x at the bottom hinge. As the moment created by the upper hinge is so much greater than the lower hinge, then the net effect will be a deflection in the direction that the upper hinge force is acting.

This may make it *look* like the upper hinge has a greater force on it, but that's not how it works. Just imagine the same gate, but with the *top* of the post anchored to a non-moving overhanging support. You can bet your bottom dollar that the bottom of the post will kick out due to deflection rather than the top moving, even though, as far as the gate and hinges are concerned, nothing has changed. You saying that in this scenario, suddenly the bottom hinge has more force, even though nothing other than the post mount location has changed?

I don't claim to have an answer to why top hinges tend to wear first, though I have some ideas that are far too long to try to type right now...

It's an interesting thought experiment for sure. I always thought gates were simple, but it's become apparent that there is FAR more to it than I thought lol.

Tom...

[tapwelder]

What type failure are folk considering for the top hinge?

If it is shearing or wallowing of the top hinge, perhaps it is because the top can move farther than the bottom without significant affect on the bottom since the bottom is the fulcrum and the length of the fence is the lever.

Could be poor maintenance or installations of the hinge. For barrel hinges: Bottom hinges will most always be installed pin up because during installation the gate is set on it. While without consideration the top hinge will be installed cup up allowing rain and rust to cause problems. Nobody will ever grease a barrel hinge.

Also, most quality barrel hinges are 4 part: A bearing, two cup and a stainless steel pin press fit in on side. I have never seen one shear.

Though, I have seen multiple a two barrel part seize and fail when moved.

Most commercial failure are from vehicle damage or over swinging, hence Something to be considered when building gate, ease of replacement and availability of parts.

[GBM]

I need to make a farm gate in the next few weeks....so this thread is very timely for my research...
What I have learned from this thread is that I need to make a rolling gate since I have the room to each side of the road... will eliminate a lot of potential problems right from the start. Thanks for the great descriptions of the physics...

[Donald Branscom]

I cannot believe you took this job with so little experience.

Anyway... The ends of the gate that have the lock or connection in the middle need to have wheels on them with springs that allow travel up and down over the uneven surface.


You better get out and start looking at other gates right away before you build anything.

The metal tubing for the gate does not need to be 1/4 thick. It is too heavy unless you plan on it actually stopping a vehicle. It is just for looks.

Square tubing is 16% stronger than round tubing.
Really think about the total weight of the metal.
Make the posts very strong like 6 inch x 6 inch steel tubes 1/4 to 3/8 thickness.
Budget allowing. Like BOOSTINJDM mentioned allow for corrosion in case they are not taken care of.

You might get galvanized tubing at a scrap yard at a good price for the posts.

I am a sculptor so it drives me crazy when a welder gets a gate job and puts up horizontal or vertical bars.
This is a chance to really do something. LOOK AROUND ON the INTERNET AT ALL THE GATE DESIGNS

BTW here is some gate wheels but you want ones that swivel.
http://i55.tinypic.com/30a7710.jpg

Some gate designs to help you.

http://i52.tinypic.com/51ye6c.jpg

The bottom portion could be helpful.
Also make the top rail of your gate CURVED. Just that one idea will make
your gate stand out from all the other gates.
CURVES show confidence.

Engineer it but- CREATE it.
Just an example to scare you...LOL
Antony&Simon Robinson design
http://i56.tinypic.com/2128fao.jpg

You said you had lots of 3/8 rod.
So I worked up this idea. for two of these gates or it could be one split in half.
Just a rough sketch.
http://i56.tinypic.com/15hzmzd.jpg
http://i53.tinypic.com/2q04nf6.jpg

[Donald Branscom]

More ideas .
Something traditional?
http://i52.tinypic.com/16c89jn.jpg

[Donald Branscom]

If I was designing the gate I would not want it to look like a military checkpoint.

I would want it to be elegant. Even if it was for a corporation. LOL...:cool2:

Even if it is a really simple gate you can see just how much a curved top really makes the gate look good.
http://i51.tinypic.com/2lo4w8w.jpg

And those posts are good too.

[steve45]

Wow, Donald! That first gate looks like somebody already drove a truck through it!

[oxygen454]

"Square tubing is 16% stronger than round tubing."? After a thurow search on google... I think I just learned something new on this statement although there is a lot of mixed feelings on this? From what we learned in school, round tube or pipe is much stronger than square. Often seen in bridges and roll cages.
Some say square is stronger and less likely to collapse, then why would they not use it in roll cages? Weight issue?

[Boostinjdm]

Square is only stronger in certain directions and weaker in others. Round has the same strength in all directions. That makes it good for cages.

[Knotbored]

I am considering a wide curving gate ( still a maybe) too.
I am considering doing something unusual and like some comments.
I might use conduit or other thin tubing/pipe filled with foam sprayed from those insulation cans.
my reasoning:
I have seen scaffold planks made from 1/4" plywood sandwiching 2" foam that are light, strong deflect very little when heavy loads are placed on them-much stronger then 2X12 commonly used.
I think filling tubes with rigid foam will prevent the tubes from collapsing and make the gate much stronger per pound.

[Donald Branscom]

Wow, Donald! That first gate looks like somebody already drove a truck through it!

That was the last link shown. Just to show extremes.
The first one was very traditional. Might want to go back and check that out.
Thanks Steve.

[Donald Branscom]

I am considering a wide curving gate ( still a maybe) too.
I am considering doing something unusual and like some comments.
I might use conduit or other thin tubing/pipe filled with foam sprayed from those insulation cans.
my reasoning:
I have seen scaffold planks made from 1/4" plywood sandwiching 2" foam that are light, strong deflect very little when heavy loads are placed on them-much stronger then 2X12 commonly used.
I think filling tubes with rigid foam will prevent the tubes from collapsing and make the gate much stronger per pound.

I would just weld the ends of the tubes closed for strength and for corrosion resistance.
As far as putting foam in them ,I do not know how you would do that and if it ever needed a repair that foam would catch fire and make toxic fumes for another welder in the future.
I would think about that. You might even be the one coming out to do the repair or modification.

[Donald Branscom]

Square is only stronger in certain directions and weaker in others. Round has the same strength in all directions. That makes it good for cages.

They use square tubing for motorcycle frames. I agree you have to know what use is the best.

A roll bar that is square could cause injury to a driver from the 90º corners.
I do not see many bridges, built with round tubing. IT is just the design requirements.
A square tube weighs more, and race cars have a lot of tubing so the round tube also cuts down on the weight.

[Donald Branscom]

"Square tubing is 16% stronger than round tubing."? After a thurow search on google... I think I just learned something new on this statement although there is a lot of mixed feelings on this? From what we learned in school, round tube or pipe is much stronger than square. Often seen in bridges and roll cages.
Some say square is stronger and less likely to collapse, then why would they not use it in roll cages? Weight issue?

I cannot give you the engineering data but if you look it up in Machinery's hand book it lists most of the facts. I think it is just how it is designed and sometimes it is for looks. The total area of the inside of the square tube is larger than a round tube. Strength of a tube is Area 1+area 2 (outside)= strength.

"After a thurow search on google" After a thorough search on Google

[Donald Branscom]

I found this helpful guide on the net.
case # case 1 case 2 case 3 case 4
tube type square round thick round big round
dimension 2.000 2.000 2.000 2.5123
wall thick 0.125 0.125 0.1624 0.125
Area, A 0.9375 0.7363 0.9375 0.9375
% wt of sq 100% 78.5% 100% 100%
Moment, I 0.5518 0.3250 0.3988 0.6697
% I of sq 100% 58.9% 72.3% 121.4%
normalized I 0.5885 0.4414 0.4254 0.7144
% nor I of sq 100% 75.0% 72.3% 121.4%
The areas are indicative of weight (wt = area * length * density).

Case 1 vs 2: The round tube of same outer dimension and wall thickness will weigh less than a square tube. It is much less stiff (based on the moment), though not as much if the moment is normalized by the cross-sectional area.

Case 1 vs 3: For a round tube of the same outer dimension as the square tube to weigh the same, it must have a thicker wall. This does increase the stiffness over case 2, but it is still less than the square tube. Considering normalized stiffness (on a per weight basis), it is slightly less than case 2.

Case 1 vs 4: For a round tube of the same thickness and having the same weight as a square tube, the outer diamer must be larger. Here we see that for the same weight, this larger diameter tube is significantly stiffer. Normalizing the stiffness to the weight doesn't matter, since the weights are the same.

Some of you have asked about torsion. The torsional moment, J is simply the sum of the moments about each axis. Since the shapes above have symmetry, Ixx and Iyy are equal, so J = 2 * I. Torsional stiffness has the same relative values. <READ THIS AGAIN.

Formulas used: D = OD, d = ID
Area of round tube = PI/4 (D^2 - d^2)
Area of square tube = (D^2 -d^2)
Moment of inertia, round tube = (PI/64)*(D^4 - d^4)
Moment of inertia, square tube = (1/12)*(D^4 - d^4)



So it makes more sense for a racing car to use round tubing because it protects the driver by being rounded,
It has less weight.

But for a fence or gate the weight and round shape is not as important.
A larger tube costs more PER POUND for the fence when you add up all of the parts.
Also the square tube takes less fitting and cutting to fit together properly. Good for fences and gates.

[Donald Branscom]

I understand the theory, calculating a lever with a fulcrum point located with a distance of almost zero from the load. However, 200 lbs at 10' is not going to exert 200,000 lbs, or 100 tons, on the gate's attachment point.

Good Luck

"calculating a lever with a fulcrum point located with a distance of almost zero from the load" It would be ZERO.

Yes that is correct. A one inch weld is about 85,000 pounds PSI tensile strength, with steel. A 200 lb. person could bend a beam down with a 10 foot long lever. Even if it was 1/4 inch thick.

So a 3 inch long weld would hold that much, but of coarse the tubing would bend first.

Then we would need to figure the pin to pin strength of a beam loaded from one end.
Would have to determine the size of a beam or tube.

I will just take a wild guess.... but I think that even a 4 inch tube would bend before the weld broke with a 200 pound
person standing on the opposite end 10 feet from where it is attached.

That is why a lever can exert so much force.

You can look this all up in Machinery's hand book.

BOTTOM LINE....A 15 foot gate WILL NEED a wheel to support the outer end of that gate. No question about it. UNLESS it is built properly.
Like doing the necessary math.

[Donald Branscom]

Oxygen454 sez:

"Thats what I have found when building gates. The top hinge seems to fail first"

Dave sez:

"Me-too!"

Makes sense to me.

[Donald Branscom]

Another one of Donald's totally inaccurate statements.

This guy sure "throws out" a lot of BS with nothing to back it up.

Oh, and Donald. Yes I am an engineer (Civil and Industrial) and got a couple degrees to back it up. Also registered as a PE in four states.


So if a 200 lb. person sits on a gate 10 feet out from its pivot or hinge point ,HOW much force do you say is being applied to the hinge or attachment?

It is so great that an actual engineer can answer our question.
But maybe it is unfair of us to ask you to show us for no pay. Don't mean to be disrespectful.

[Donald Branscom]

Here is a gate that did NOT work.
http://i55.tinypic.com/33w8kme.jpg

[Donald Branscom]

sorry double post

[sn0border88]

So if a 200 lb. person sits on a gate 10 feet out from its pivot or hinge point ,HOW much force do you say is being applied to the hinge or attachment?


Easy, anyone who has taken a basic statics course should be able to answer that. The gate will see the same 200lb downward force whether it is being applied 1' from the pivot point or 50' from that same point. However, torque will increase with distance from the hinge point. So a 200lb load applied 10' from a point will create 2000 ft-lb of torque at that point. (200lb)(10')=2000 ft-lb

Dont believe me? Heres the same snapshot from my statics book that I put up in the last thread where you tried to spread that nonsense.

http://i298.photobucket.com/albums/mm280/m_hoover/e3df0470.jpg

[sn0border88]

Here is a gate that did NOT work.
http://i55.tinypic.com/33w8kme.jpg

Looks like it works just fine to me, it keeps large vehicles off the foot path. It doesnt have to be a work of art, just functional.

[Donald Branscom]

Looks like it works just fine to me, it keeps large vehicles off the foot path. It doesnt have to be a work of art, just functional.

I would agree. Scorpio "functional." Right.

As an artist/sculptor I really like to take any opportunity to make an artistic work even if it is "just a gate"

[Donald Branscom]

Easy, anyone who has taken a basic statics course should be able to answer that. The gate will see the same 200lb downward force whether it is being applied 1' from the pivot point or 50' from that same point. However, torque will increase with distance from the hinge point. So a 200lb load applied 10' from a point will create 2000 ft-lb of torque at that point. (200lb)(10')=2000 ft-lb

Dont believe me? Heres the same snapshot from my statics book that I put up in the last thread where you tried to spread that nonsense.

http://i298.photobucket.com/albums/mm280/m_hoover/e3df0470.jpg

OK ... Sorry i did not have my terms correct. I am not an engineer.
The term is "TORQUE" 2,000 ft. lbs. torque.
I do not have any reason to not believe you.Sincerely.

[sn0border88]

OK ... Sorry i did not have my terms correct. I am not an engineer.
The term is "TORQUE" 2,000 ft. lbs. torque.
I do not have any reason to not believe you.Sincerely.

Your still missing the point where you say it needs to be multiplied by 1000, thats just completely wrong and misleading. A 1lb force at 1' creates 1ft-lb of torque, not 1000ft-lb.

And as for making every gate a work of art... You have an obvious disconnect from the real world. Sometimes (often times) functional and simple trumps artsy.

[oxygen454]

You guys take these hinge systems waaay to seriously :rolleyes:

[Sandy]

Easy, anyone who has taken a basic statics course should be able to answer that. The gate will see the same 200lb downward force whether it is being applied 1' from the pivot point or 50' from that same point. However, torque will increase with distance from the hinge point. So a 200lb load applied 10' from a point will create 2000 ft-lb of torque at that point. (200lb)(10')=2000 ft-lb

Dont believe me? Heres the same snapshot from my statics book that I put up in the last thread where you tried to spread that nonsense.

http://i298.photobucket.com/albums/mm280/m_hoover/e3df0470.jpg


Here is what you're saying in full size text.

Torque = Force applied x lever arm
(scroll down to see example in LBS)

http://hyperphysics.phy-astr.gsu.edu/hbase/torq.html#torq

Torque Calculation
(caculate other than 90° forces)

http://hyperphysics.phy-astr.gsu.edu/hbase/torq2.html#tc

[Donald Branscom]

Here is what you're saying in full size text.

Torque = Force applied x lever arm
(scroll down to see example in LBS)

http://hyperphysics.phy-astr.gsu.edu/hbase/torq.html#torq

Torque Calculation
(caculate other than 90° forces)

http://hyperphysics.phy-astr.gsu.edu/hbase/torq2.html#tc

Thanks Sandy for posting that.
So 50 lbs.torque x 2 feet =100 ft.lbs torque and so 50 ft. lbs. x 10 feet would be 500 ft.lbs. lbs. of torque!

200 ft. lbs. torque x 10 feet= 2000 ft. lbs. of torque.

So if the gate is all one piece 15 ft. in length and ONE 200 lb.person
sits on the end of the gate that would be 200 ft. lbs. x15 feet =3,000 ft. lbs of torque on the gate.

So then you can go to Machinery's handbook and look up the strength of a box beam
supported on one end and 3,000 ft. lbs. of torque and find out how much torque would be applied to the fence post through the hinges. If ONLY one person sat on the end of the driveway gate.

I think this is a GOOD reason to NOT make the gate a comfortable height or design to sit on. Decrotive points sticking up on the gate would also discourage that.

The drawing posted by ZORA the original poster on this thread had a drawing depicting a gate 42-3/4 inches high. A rectangle gate.
It did not show a measurement for the height above the ground but ZORA said the gate (if it had a wheel for support). would have to travel over uneven ground and the wheel would have to travel up and down 18 inches! That means the bottom of the gate would have to be 18 inches above the ground.

I have a solution...

I will post a drawing. See LINK below.
But the gate would be better as a triangular gate since its purpose is to prevent cars form entering and it is obviously not to prevent people from crossing.
This is a low cost ,simple solution.
This gate takes into account the uneven ground (18 inches). No wheel need. Spend the money on the post.
It keeps the weight down.
It would use 3 inch square tubing.1/8 thickness. Easy to fit and cut. Top tube about 40 lbs. and with .095 wall tubing it would be less.
All tube ends welded closed! A must for corrosion protection.
The post would be 8 x 8 inches and as thick as you can afford with your budget. Think about corrosion.
Gate 15 feet.
http://i54.tinypic.com/1z15qut.jpg

[denrep]

FWIW - With years of service behind them, today, there are probably at least a million sliding industrial gates of the proven cantilever design. These gates are often of a solid-panel design with openings in the 20' range, even so, they usually do not utilize any ground-bearing load wheels.

Though the typical large solid-panel gate may easily approach or exceed a 1000lbs in weight, it usually can be opened almost effortlessly and would easily support the hypothetical 200lb person standing on its end, as well as deter entry by "ramming" with a vehicle.

My point is that very good gates do not require anywhere near some of the materials being suggested here. Overbuilding with the wrong material in the wrong place does not make for good design. A small bit of good engineering along with proven practical design is worth a thousand fold in misinterpreted or misapplied engineering data.

Good Luck

[Donald Branscom]

FWIW - With years of service behind them, today, there are probably at least a million sliding industrial gates of the proven cantilever design. These gates are often of a solid-panel design with openings in the 20' range, even so, they usually do not utilize any ground-bearing load wheels.

Though the typical large solid-panel gate may easily approach or exceed a 1000lbs in weight, it usually can be opened almost effortlessly and would easily support the hypothetical 200lb person standing on its end, as well as deter entry by "ramming" with a vehicle.

My point is that very good gates do not require anywhere near some of the materials being suggested here. Overbuilding with the wrong material in the wrong place does not make for good design. A small bit of good engineering along with proven practical design is worth a thousand fold in misinterpreted or misapplied engineering data.

Good Luck

What do you suggest? Would you post a sketch?
BTW ...I would make sure the gate is high enough that no one is encouraged to sit on the gate.
But i am sure it will be .
I would also count on more than one person sitting on it at one time if it was the height that encouraged people to sit on the gate.

A sliding gate requires a track in the ground for the wheel.
I know from experience that if THIS gate was a sliding gate and the track was above the ground some cars may snag that above ground track because the ground slopes.
downwards on both sides of the high point where the gate track would be located.
The gate track would have to be in the ground.
I have been told that if a car snags the gate track with a sliding gate that most insurance companies will not pay.
The property owner would be liable, and the builder too. Or both.

My Jaguar snagged one of those above ground tracks and it broke my exhaust and cracked the exhaust manifold.
It got very expensive. The previous property owners had tried a above ground track and it got snagged many times
because of the slope on both sides of the track.
But each new owner of the property was not told about the problem and kept on repeating the mistake.
I worked with the property owner and he got my car repaired at his company shop.

[Donald Branscom]

ZORA,
I hope that you will post a photo of your finished
gate . Thanks!

[denrep]

What do you suggest? Would you post a sketch?
BTW ...I would make sure the gate is high enough that no one is encouraged to sit on the gate.
But i am sure it will be .
I would also count on more than one person sitting on it at one time if it was the height that encouraged people to sit on the gate.

A sliding gate requires a track in the ground for the wheel. . . .

No track or wheels on the ground, that's asking for trouble in snow country.
Gate panel caged between four rollers, rollers turn on precision bearings.

Height typically 5' - 7' depending on use.
Gate frame typically rectangular tube.
Screen typically roll formed panel, per steel-building siding.

When I get a chance I'll post a picture or two.

Good Luck

[Donald Branscom]

No track or wheels on the ground, that's asking for trouble in snow country.
Gate panel caged between four rollers, rollers turn on precision bearings.

Height typically 5' - 7' depending on use.
Gate frame typically rectangular tube.
Screen typically roll formed panel, per steel-building siding.

When I get a chance I'll post a picture or two.

Good Luck

Interesting.. Never lived in snow country.
Although it may snow in San Francisco tomorrow. Not kidding. LOL
Another beautiful gate.
http://i54.tinypic.com/2rdde89.jpg
Sort of Arnold Bocklin style c1960

[denrep]

Here's the domesticated version, with wood screen:
63506

[Donald Branscom]

Thanks for posting that pick of that snow country "domesticated" gate. LOL....lol
The wood fence boards would help keep the weight down too.
Gives some privacy.

[Donald Branscom]

I wonder how ZORA is doing on that gate project?

Tap...tap....tap...;)

[denrep]

Thanks for posting that pick of that snow country "domesticated" gate. LOL....lol
The wood fence boards would help keep the weight down too.
Gives some privacy.

Actually the wood is heavier than steel siding, more difficult to clear the rollers with, and doesn't add rigidity to the gate's frame the way steel does, but it's a trade-off for the domesticated appearance. I'll try to post pictures of the wild uncouth all-steel type too.

Good Luck

[oxygen454]

I wonder how ZORA is doing on that gate project?

Tap...tap....tap...;)

I think you guys scared him away with all the physics and math LOL :laugh:

Have learned a lot from the posts in the thread. The weight factor is very interesting. I did not think the cantilevered weight load would be in the thousands of pounds!

[zora]

here's an update. It's been cold as hell lately and I haven't really been motivated to go in the garage and work, But the last week or so has been really nice so I've made some progress.

Dave really gave me some great insight on building hinges so I built my own out of 1.5x.120 DOM and some 1.25 cold rolled round. Dave would say that they aren't big enough, but they are orders of magnitude better than what I was gonna use.
I plan on welding the hinges to some 2x.250 sq tubing which I will bolt to the posts with 3x 1/2" grade 8 bolts.

As for the actual gate, It's really hard to make something strong, light, and beautiful with a very small budget. The pictures are where I am right now. the frame is 188"x40" 2x14ga tube. everything else is .250 plate and 9/16 round.

If it doesn't work, I'll just throw a wheel on the end. I am trying not to, but we'll see. My client doesn't care either. He just wants a gate.

I really appreciate everyone's input. I'll keep you all posted.

B

[oxygen454]

Looking much better already! Is that DOM tube you are using for the hinges? I hope so, I find normal structural pipe splits under load. The weld can be a major PITA as well.

[zora]

Is that DOM tube you are using for the hinges? I hope so, I find normal structural pipe splits under load. The weld can be a major PITA as well.

DOM it is. I was playing with the sizes and with 1.5x.120 tube and a 1.25 round pin gives me 0.010 gap which is nice and tight. It's the best I can do without a lathe.

[oxygen454]

Very nice. The other thing I have done in the past is drill half way down the solid shaft and then 90 degrees. Then tap the top for a grease nipple. Works great. I also have tapped and installed grease nipples through the DOM.

[tapwelder]

Once I made a hinge. I found that .008" was the tightest the gap should be to compensate for welding shrinkage. Got a lot of practice turning hinges that day.

[zora]

Once I made a hinge. I found that .008" was the tightest the gap should be to compensate for welding shrinkage. Got a lot of practice turning hinges that day.

Thats the part that freaked me out because I really didn't know. I had the pieces cut for a month or so, just never got around to welding them up because of some low level anxiety that the welding would distort the DOM just enough to ruin my day. But it ended up being ok, they are a little tighter , but not as bad as I thought they would be.

[zora]

Very nice. The other thing I have done in the past is drill half way down the solid shaft and then 90 degrees. Then tap the top for a grease nipple. Works great.

That is where experience is priceless. Sounds like a whole lot less work than what I came up with... cutting end plugs , drilling/tapping, and welding . Who knew? :drinkup:

[oxygen454]

LOL Well as long as you have a grease system then its all good. I had a friend that wanted no grease options on his gate I built him... needless to say the hinge failed and I ended up putting in the grease option. (water and rust "froze" the hinge to the point I had to torch the hinge off)

[denrep]

. . .I plan on welding the hinges to some 2x.250 sq tubing which I will bolt to the posts with 3x 1/2" grade 8 bolts. . . .

Zora - May I suggest that the hinge pads seen in reply #94 should be tied to three sides of the tube to more evenly distribute load?
As seen in the picture, I'm worried that they'll pull the tube wall out.

Good Luck

[denrep]

There was no budget for this gate, not even enough for its own thread.
And the painters are still on strike, seems like ever since Reagan cut the traffic controllers loose. :laugh:

Piercing holes so that an angle can be bolted to the gate panel's edge.
65584

Mounted the hinges to the gate post and gave ‘em a shot of grease.
65585
The gate was ready to hang, except... there was a few week delay and we lost the bearings for the hinges; can't find ‘em anywhere.

Alfred to the rescue. He knew where we could get some replacement bearings:
65586
Oops, new problem, the hinges won't drop together now.
Oh, no wonder, we just found the missing bearings, they're already in the hinges. :laugh:
But now we can't get the extra bearings out.

Alfred to the rescue again:
65587
A welder-powered electromagnet pulled the extra bearings, no problem.

Finally, the panel is up:
65588
The saffety chain at the top is so if the earth flips on its axis the panel won't get too far away.

One more:
GATELATCH
The gate's just over 13 feet long. A 225lb weakling can stand on the latch end, no problem.

Oops, I guess we hit the glass ceiling of picture posting. :laugh:

Good Luck

[zora]

Zora - May I suggest that the hinge pads seen in reply #94 should be tied to three sides of the tube to more evenly distribute load?
As seen in the picture, I'm worried that they'll pull the tube wall out.

Good Luck

That makes two of us. Actually I'm worried that my welds won't hold but that remains to be seen. but it is all welded and greased up so I guess I'm done, right? :drinkup: I'll probably hang it later this week, I'll keep you all posted.

]
A welder-powered electromagnet pulled the extra bearings, no problem.


I love it. Someday when I'm bored I'm gonna play with welder powered electromagnetism.

[Donald Branscom]

Do you own a grinder?

[zora]

Do you own a grinder?

hopefully I won't need it. My welds probably will hold, but I've never really welded anything where the strength mattered so much and it just makes me nervous. I guess I'm kind of a virgin. :blush:

[Donald Branscom]

hopefully I won't need it. My welds probably will hold, but I've never really welded anything where the strength mattered so much and it just makes me nervous. I guess I'm kind of a virgin. :blush:

I was not thinking that.

I was wondering why I could not see any clean ground metal around the welds.
Just saw a lot of rusty metal.

[mb_welder]

the biggest gate I've built had a 16" heavywall pipe for the post and I think the gate itself was made out of 5" or 6" I beam, if I recall correctly. :dizzy:

[zora]

I was not thinking that.

I was wondering why I could not see any clean ground metal around the welds.
Just saw a lot of rusty metal.

I guess it shows where my mind is. Anyways I did clean up before I welded but then they sat outside for a few weeks.

I just delivered them today, and I'll head out next week to hang them.

[denrep]

Zora - Your work looks plenty clean.
I'm guessing that Donald Branscom was commenting on reply #103.

I asked Alfred, he said he has two grinders for this type of work, model 6010 and 6011. :laugh:

Good Luck

[zora]

tada!! I finally got my gates hung. I really want to thank everyone here who helped me out. You've save me countless tears. If you didn't know any better you might actually think that I knew what I was doing. :drinkup:

I don't know why I was so worried that they wouldn't be strong enough. I can actually hang off the end and swing on it. :) They just seemed very heavy when I would move them around in my shop. (and my wife who was helping me said there is no way they would stand up) And I kept having visions of the posts bending over.

I filled the posts with concrete and rebar and put a piece of angle iron in the center to support it just in case. (it is next to a high school and I'm certain that a bunch of kids will be sitting on it.)

I don't know what happened to my 1/2" gap I had planned where the gates meet, but it's gone and they meet almost perfectly. I have zero gap at the top and about 1/8" at the bottom, but across 30' and being my first one, I'll take it.

I did it for a good friend of mine and gave him a deal but I don't have any idea what gates like that should cost? I'm guessing that it's somewhere near $150/foot or $4500 . Is that the right ballpark?

Also, I'd like to show them off in the projects section. Do I make a new post or have a mod move this one?

Thanks again.

B

[Boostinjdm]

I did it for a good friend of mine and gave him a deal but I don't have any idea what gates like that should cost? I'm guessing that it's somewhere near $150/foot or $4500 . Is that the right ballpark?

$4500? How many do ya want. Order 10+ and I'll go kick in the door of the steel supplier and get started right now.

If I had to make a guestimate on that gate. I'd prolly say $2500 would be the upper end, but I work cheap.... Don't know really, that's why I just go hourly.

[Donald Branscom]

Looks like your gates turned out ok.

As far as the price it should be materials + hourly rate.

But you should have made all of this clear with the person you were building them for before the job started, otherwise it could lead to resentments or arguments if the client thinks it cost too much and if you think you are not being fairly paid for your labor and materials.
I would keep that in mind for the future.

[Donald Branscom]

$4500? How many do ya want. Order 10+ and I'll go kick in the door of the steel supplier and get started right now.

If I had to make a guestimate on that gate. I'd prolly say $2500 would be the upper end, but I work cheap.... Don't know really, that's why I just go hourly.

"I'd prolly say $2500" >I'd Probably say $2500;)

[tackit]

Up hill hinges don't look hard to build.. installation PDF at bottom of page


http://www.hardwaresource.com/hinges/GATE+HINGES+AND+HARDWARE/Gate+Pivot+and+Weld-On+Hinges/Uphill+Hinges

[zora]

If I had to make a guestimate on that gate. I'd prolly say $2500 would be the upper end, but I work cheap.... Don't know really, that's why I just go hourly.

Thanks, That's why I asked. I really have no idea. Last summer I did my first big project and did it $10,000 too cheap. http://weldingweb.com/showthread.php?t=47188 Then a couple of months ago I did a little stair railing http://i.imgur.com/91oh4.jpg (http://imgur.com/91oh4)and after it was all done, my client told me I was the highest bidder, but he picked me because I had good service.


As far as the price it should be materials + hourly rate.

But you should have made all of this clear with the person you were building them for before the job started.

I thought about materials + hourly, but I was thinking that gates/railings/fences were priced per foot. I kinda figured that the cheapest steel railings you can get are ~$50/ft then kinda estimate up from there.

About the price upfront. I totally agree but it all started over a couple of beers and went kinda like this:
Bob: "hey, you think you can build me some gates?"
me: "I don't know, I'll try."
Bob: "cool, let's do it"

Up hill hinges don't look hard to build.. installation PDF at bottom of page


http://www.hardwaresource.com/hinges/GATE+HINGES+AND+HARDWARE/Gate+Pivot+and+Weld-On+Hinges/Uphill+Hinges
never heard of such a thing. looks interesting.

[Boostinjdm]

"I'd prolly say $2500" >I'd Probably say $2500;)

You still got the point without having to hire a code cracker....:waving:

[Donald Branscom]

Thanks, That's why I asked. I really have no idea. Last summer I did my first big project and did it $10,000 too cheap. http://weldingweb.com/showthread.php?t=47188 Then a couple of months ago I did a little stair railing http://i.imgur.com/91oh4.jpg (http://imgur.com/91oh4)and after it was all done, my client told me I was the highest bidder, but he picked me because I had good service.



I thought about materials + hourly, but I was thinking that gates/railings/fences were priced per foot. I kinda figured that the cheapest steel railings you can get are ~$50/ft then kinda estimate up from there.

About the price upfront. I totally agree but it all started over a couple of beers and went kinda like this:
Bob: "hey, you think you can build me some gates?"
me: "I don't know, I'll try."
Bob: "cool, let's do it"


never heard of such a thing. looks interesting.

Bob: "hey, you think you can build me some gates?"
me: "I don't know, I'll try."
Bob: "cool, let's do it"

SOME marriages got started that way too, but the results were disasterous!!

Unclear what each party was expecting. Know what I mean?

[fortyonethirty]

Thanks, That's why I asked. I really have no idea. Last summer I did my first big project and did it $10,000 too cheap. http://weldingweb.com/showthread.php?t=47188 .

If you had to do it again what would you have charged? What went wrong?

[zora]

If you had to do it again what would you have charged? What went wrong?

$10,000 more. ;)

Inexperience mostly. I figured out my materials, then figured $3000 for me. I was gonna make $3000!!! :drinkup: I had no idea how big of a project it actually was. Hundreds of hours of weekends and evenings. A pissed off wife because I spent every free moment in the garage. I had to get a crane to get the 2nd and 3rd story railings up. Lots of things really... But as I've learned: Education is expensive...

[Chuck]

Denrep - What does that say... something about "I'm still dreaming about your XXXXX "

Am I the only one who saw that?

[denrep]

Chuck, That's probably something about Alfred's smiling face...
Maybe it was from his Mother?


-----

Congrats on the gate work Zora, looks nice.

[jreynoldswelding]

Chuck, That's probably something about Alfred's smiling face...
Maybe it was from his Mother?


-----

Congrats on the gate work Zora, looks nice.

:laugh::laugh:

[Chuck]

Chuck, That's probably something about Alfred's smiling face...
Maybe it was from his Mother?




OH, I see. That makes sense. She's probably bent over rolling out pie dough or something then.

[Bgbkwndo]

[QUOTE=zora;449097]It's a 30' span so I'll be building 2x 15' gates. They will never open and I'll build a pretty substantial sliding bolt to lock them together at the center.

A gate that will never open is a "fence".

[MrBeast]

Those gates came out pretty good man.

As far as pricing goes, for a 4' tall custom gate I start at 100.00/ft, I add 10.00 per foot taller, then I charge hourly for instalation. This is because you have no idea what little burried treasures you are going to find when you start making a hole in the ground expecially when you are digging in ground that has been dug and backfilled before.

Case and point I installed a sign at the beach a few weeks ago, figured it would be easy digging because it was going in a sand/topsoil mix, not so, I got down 5" found a piece of 1" rebar, got down below that found concrete, got below that found more rebar, and a piece of pipe that all had to be cut out of the hole. It took 5 hours to dig 2 14x36" post holes. It took less time to build a jig to hold the sign, mix and pour the concrete and then paint the sign than it did to dig the hole.

This is why I bid the things I can control the cost on, and T&M the things I cant. At the same time I billed the customer at 60.00 an hour for digging the holes instead of 75.00 which is my normal rig rate to help them keep the cost down and because of it they have already called me on other jobs. Some times eating a little bit and still making money is better than alienating a customer is most cases, expecially with this economy.

You definately overkilled the posts, but that is ok, if some one ever drives through the gates, you might not have to replace the posts.