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wd40prerunner
09-11-2008, 03:28 AM
My instructor had me make some tables for other class at my hall today. I thought i knew what i was doing :nono: he let me make a few mistakes :blush2: then he showed me was to get thing square and keep them there through construction.I spent 5 hour on these two tables and I'm still not done with the last one:realmad: but with the tricks that i learned to day this could have went really smoothly.So if you have any ways or tricks could you please post them no matter what its for. thanks for any help!

BLUE2KSS
09-11-2008, 04:39 AM
why dont you post up what you learned? that might help a few people and it is the point of your thread...

I have learned that using a regular carpenters square is not good enough to square the parting tool in the lathe, but the machinist steel square is the drawer below (lol). this was three years ago now.

6010
09-11-2008, 08:18 AM
I tack opposite corners so that any draw tends to cancel out. I use a square as I go to make any adjustments. When I think I have it right I use what Pythagoras learned in 6 th century BC. And that is if opposite sides are equal, and the diagonals are equal, then it is square. Pythagoras wasn't a welder but he was pretty good with numbers.

When I cut the metal I try not to make the mistake of the carpenter who said " I have cut it three times and it is still too short ". :D

6010
09-11-2008, 09:58 AM
Another thing I have seen done if you have a lot of them to weld and you can do it on the table is to get one right. Then you can lay it on the table and tack 2 small pieces of angle at each corner and along the sides as a guide. Then you can lay the pieces in this gig, again welding tacks at opposite corners on the diagonal. This will save you some time.

Dirk
09-13-2008, 07:57 AM
Use angle plates. You can't really build anything square without them. Depending on what you are building you will always have at least one axis held square. For example if you are building something flat on the table (note: fab tables should always be blanchard ground, or at least some other machined surface) the table will hold one axis square, while the angle block will hold the other. To be efficient at fab work you have to have the tools. Any fabricators tool box should have angle plates, v blocks, and other machinist tools, without them you will get stack up in a hurry.

William McCormick Jr
09-24-2008, 08:53 PM
My instructor had me make some tables for other class at my hall today. I thought i knew what i was doing :nono: he let me make a few mistakes :blush2: then he showed me was to get thing square and keep them there through construction.I spent 5 hour on these two tables and I'm still not done with the last one:realmad: but with the tricks that i learned to day this could have went really smoothly.So if you have any ways or tricks could you please post them no matter what its for. thanks for any help!

There are a lot of things to keep square when you weld up a table. You also have to know your material and which way it is going to shrink most as you weld it. Because if your table is going to be as strong as the material it is made of. You are going to get some serious pulling as you weld it.

I miter my joints at a 45 degree angle. I only cut one face of the angle iron on a 45 degree angle and fill in the outside corner with weld.

I often use Bessemer corner clamps. I use four of them at once. So that after I tack, I just weld all four joints in the same direction. This way all the stress cancels itself out by putting equal force in one direction on all the parts. It either pulls all the sides in a bit. Or it pushes all of them out a bit. After you get it all welded you just take off your clamps and 95 percent of the time it is perfect.

Usually when I weld the legs on, I have a bit of a gap between the leg and the outside corner of the table top, after grinding. If I am using angle iron. Usually I get the most undercut right at the corners. So I actually tack the corner while it is held way off the table top. Then I square up one side one way and tack that outside corner. At this point it is still easy to break off. Then I square it up both ways and make the last tack.

After I get it tacked. I tend to weld towards the corner. Usually I weld inside and out.

If I don't grind the weld and usually today we do not. I just tack the corner, while it raised up on the weld. And then adjust and tack the two sides of the leg, after I set them with a square. Then weld them up the same way if I ground them.

You can also check square if your pieces are fairly close in length by measuring the diagonal of your table top. It should be the same across both diagonals.

You can also use a pipe clamp across the diagonals to adjust the square of your table top. Then just make another pass with TIG over the existing weld, in the direction you want it to shrink. This will hold it square after you take the clamp off.

Sincerely,

William McCormick

09-26-2008, 03:06 PM
dirk you gave me a chuckle with the blanchard ground fab table. anyone know how to blanchard grind a driveway?

Dirk
09-26-2008, 03:30 PM
dirk you gave me a chuckle with the blanchard ground fab table. anyone know how to blanchard grind a driveway?

Sorry, but I get a chuckle out of people that call themselves fabricators until that they get a print that calls for a +/- .030 tolerance on length and a .005 tolerance on perpendicularity and parallelism on a weldment with no postweld machining. If walk into a "fab shop" and their fab tables aren't machined, they're hacking not fabricating.

evildrome
09-26-2008, 08:01 PM
Hi Guys,

I have much the same problem. I want to weld up a 2ft square of 2" square pipe as a base for a CNC router project. I plan to mill the thing flat before I use it but I'd like to keep the milling to a minimum. I'm not overly concerned with distortion in the X & Y directions, just the Z. The pre-milled rails will be parallel to each other, not the base (OK, parallel in the Z axis) but it does need to be flat. The milling machine table is about 18 * 36 and is a good reference surface. I also have big 90 deg angle plates and a couple of swivel machinists vices that I could set at 90 deg to each other.

As far as lining it up square is concerned, I think I'm OK with that. Should I make square end joints or mitre joints? And how do I weld those to stop them twisting relative to each other? This has always been my problem in the past. When I've tried to weld tube into a square I always end up with one corner higher than the other.

I will be using a good DC Tig plant.

Cheers,

Wilson.

Fat Bastard
09-26-2008, 09:41 PM
I have been building tube frames for 20+ years, I have used every gadget from the magnetic triangles, mill angles, flat stock clamping things in all directions.

About 8 years a go a settled on one method, I use it on rectangular or round anything where I need to attach something perpendicular.

First I go on the assumption that all cut ends have a bias to lean in some direction, I find that bias. I locate the part (place it where it is to be) noting the location of the corner away from the direction of the lean then tack at that corner, using the tack as a hinge I will square in one direction. If done correctly I can then use the two tacks as a single hinge to square for the other direction.

This works great for when you have a wide tolerance, and you don't get skieered at seeing a gap that gets to be weldered up.

I use the same type process for building a cube like tube structure. Only difference is I never tack the inside corner until I have the cube assembled and have crossed measured for square and have it clamped square then I'll start tacking the inside corner on the side with the clamp since that is the long side and needs to shrink.

Are you all cornfused now. :dizzy::dizzy:

Donald Branscom
09-26-2008, 10:38 PM
Even though you may make your cuts on a machine you must check the cuts with hand tools anyway. A square, bevel gage, etc.,.

It is the fit up that will keep it square as well as the order that the tacks are made.
All the clamping won't keep it square if the fit up is not exact.

The welding is the easy part of the welding job. It is the measuring , fit up, CLEANING, and procedure that make the job come out right.

Donald Branscom
09-26-2008, 10:41 PM
Sorry, but I get a chuckle out of people that call themselves fabricators until that they get a print that calls for a +/- .030 tolerance on length and a .005 tolerance on perpendicularity and parallelism on a weldment with no postweld machining. If walk into a "fab shop" and their fab tables aren't machined, they're hacking not fabricating.

You mean platens?

farmersamm
09-26-2008, 10:45 PM
Now, I don't know if this qualifies as fabrication.

Certainly couldn't put this ol' thing on a machined table, or a granite check surface. Little too big:) Never seen 'em put ships on a machined table either.

Tacking correctly, and sequencing welds goes a long way to keep everything square. It just flat out doesn't take care of everything. When you apply heat, you will get distortion. Period. Every weld pulls the structure.

Now ya might get real close, but you ain't gonna get it right on the dime. It takes the extra step. You have to heat to shrink the stretched metal. If it gets heat on one side with a weld, it shrinks on the welded side, and stretches on the unwelded side. That's why somethin' bows when ya weld it. So whadya do?

Get out the tweaker.

The pics are of an old project. The first pic is a stiffener that had to be welded between the two arms on a front end loader. Adding this large mass, and welding it to the structure caused the loader arms to pull. No way around it. Now ya gotta get 'em back to square.

Bottom line, don't stress too much about somethin' pullin', just find a way to deal with it using heat. If heat got ya into trouble, it can get ya out.

Fat Bastard
09-27-2008, 11:55 AM
Sorry, but I get a chuckle out of people that call themselves fabricators until that they get a print that calls for a +/- .030 tolerance on length and a .005 tolerance on perpendicularity and parallelism on a weldment with no postweld machining. If walk into a "fab shop" and their fab tables aren't machined, they're hacking not fabricating.

Well aren't you just the the man. lol

You really think all "real fabricating" is done to such tolerances? Climb down off that high horse and walk among the people, :cool2:

I sure loved when I had a "ground flat" table to work from but like the man said its the skills not the tools that make him great. ( :blush: )

tnjind
09-27-2008, 12:08 PM
Amen, Fb.

JTMcC
09-27-2008, 04:59 PM
If walk into a "fab shop" and their fab tables aren't machined, they're hacking not fabricating.

It's a big, broad welding world out there man and YOUR expierience is just a tiny part of it.

I have friends that I've known for many years that personally net over 1/2 a million per year "fabricating" off the back of a truck in the great outdoors, the sun on their backs and the wind in their face, with no fab table in sight, much less a "machined" table. They would be amused at your "hack" comment.

It's rough when you have exhausted every legitimate investment option (to the max allowed) that the irs allows, and have to find creative outlets to "shelter" your "hack" income from the government thugs ;)

JTMcC.

evildrome
09-27-2008, 08:03 PM
"If heat got ya into trouble, it can get ya out."

I've seen this before in body shaping forums. Heat shrinking is a "black art" known only to the few. Everyone understands the principle but its the doing of the thing thats the trick.

I expect we could fill a whole forum full of posts on it. I think to learn it I'd have to see someone do it. Thats how I learn everything else. Anyone volunteering to do a You Tube video tutorial?

Cheers,

Wilson.

William McCormick Jr
09-29-2008, 09:12 PM
Even though you may make your cuts on a machine you must check the cuts with hand tools anyway. A square, bevel gage, etc.,.

It is the fit up that will keep it square as well as the order that the tacks are made.
All the clamping won't keep it square if the fit up is not exact.

The welding is the easy part of the welding job. It is the measuring , fit up, CLEANING, and procedure that make the job come out right.

http://www.airgas.com/browse/product.aspx?Msg=RecID&recIds=132853&WT.svl=132853

I have been using four or these for over 20 years. They will hold poorly cut pieces square, if you use four of them on a frame at the same time.

You will get a little bowing either in or out, on the lengths depending on which way you weld them. I always weld in the same direction and they all pull the same way, either in or out.

I would not even think about taking on a job without them. This is how to do it if you get a short run of frames to weld.

Here are some knock off's that look pretty good. However I have never used them. They do look good though.

After all the years of using the Bessy clamps I would probably stick with them.

Sincerely,

William McCormick

hotrodder
09-30-2008, 01:11 PM
"If heat got ya into trouble, it can get ya out."

I've seen this before in body shaping forums. Heat shrinking is a "black art" known only to the few. Everyone understands the principle but its the doing of the thing thats the trick.

I expect we could fill a whole forum full of posts on it. I think to learn it I'd have to see someone do it. Thats how I learn everything else. Anyone volunteering to do a You Tube video tutorial?

Cheers,

Wilson.

There's already video of flame shrinking on youtube, a very basic snippet with sheetmetal but at least you can get an idea. I would provide a link but it's something i stumbled over when looking at various metal shaping vids. Try searching for metal shrinking

IIRC the video shows the heated spot being quenched with a wet rag which is one of several methods. All depends on the situation- the last time i did any was on a car bonnet (hood) that was fire damaged, only areas that were backed with strengthening ribs were quenched with a wet rag.

The thing that takes some getting used to is that during the heating phase the panel gets a lot worse!

Capnbondo
09-30-2008, 01:37 PM
The thing about heat straightening is it's very much experience based IMO. It is trial and error.

It takes quite a bit of practice to know how much heat to apply and where to apply it.

I mean there's a bit of technique/science to it, but I guess what I mean to say is there's not much of a formula where you can say: "well, my 1.5"x1.5"x1/8" square tubing is warped "x" amount, so I'll apply "y" amount of heat at "z"."

It's kindof a "feel" thing.

What I suggest is to heat/quench a little at a time and observe. It's better to do it 2 or 3 times than over-do it and warp it back the other direction. Then you start to chase your tail so to speak.

hotrodder
09-30-2008, 01:51 PM
It can approach that level of science (i did post a link to a book excerpt a while ago, will dig it out later as i'm on my out) but yeah, like welding/wheeling/panel beating etc it's one of those things that you're constantly learning- the curve may flatten out some with time but it never gets to be straight

farmersamm
09-30-2008, 10:20 PM
I've never done it with anything like bodywork. Usually with pretty heavy stuff.

As long as you put force in the direction you want the metal to go, heat the opposite side to a dull orange(nowhere near melting), and let it cool down while listening for a tick tick like an engine block cooling down, you will have movement in the desired direction. If you don't hear the sound of the contracting metal, you know there wasn't enough force on the part. Sounds goofy, but it's the way I've figured out to make it work pretty predictably.

I usually do it in degrees. I don't try to make the move all at once. I've had the bad experience of going too far.

Oldtimer
10-01-2008, 11:12 AM
I have to pretty well agree with Fat Bastard on both his posts. Sums it up pretty good.

How to build things that are square comes with experience. You learn what to tack where and which direction to weld what and in what sequence as you gain experience. After you pull enough of your projects out of square when you weld them up, you kind of figure out what to do to keep everything where it is supposed to be and how to fix it if you mess up.

A_DAB_will_do
10-01-2008, 02:00 PM
I'm surprised that I didn't hear anyone specificly mention using a bubble level to fab things up square.

For those of use without granite reference tables or blanchard ground steel table tops, a level works wonders.

Level, square, and plumb each piece of the assembly as you tack them in place. If the first horizontonal member is level, the first vertical member is plumb, and both are square with respect to one another, then all subsequent pieces can be assembled relative to the first. If you've cut everything accurately to the correct lengths, then the resulting work will be right on.

Lots of small tacks are better than a few big ones. Each tack introduces some shrink or distortion, so keep them small. Use lots of tack welds to prevent the finish welds from stretching the tacks.

Keep your welds as small as possible. Big welds make for big distortion. Most people(myself included) massively over do it when it comes to weld size. Bigger may make for stronger joints and better feelings about the work, but it makes for lots of distortion too.

For structures made from angle iron, I usually tack the right angle corner(the bottom of the 'V' in the angle iron), with a spacer create some root opening and room to move the piece around. Then tack one corner, level and/or square the perpendicular direction, and make a third tack weld on the other corner.

digr
10-07-2008, 10:08 PM
--------------------------------------------------------------------------------

Fast and easy way to square frames and uprights.

Dirk
10-15-2008, 07:18 PM
Well aren't you just the the man. lol

You really think all "real fabricating" is done to such tolerances? Climb down off that high horse and walk among the people, :cool2:

I sure loved when I had a "ground flat" table to work from but like the man said its the skills not the tools that make him great. ( :blush: )

Not all fab work is done to that close of a tolerance, but that doesn't mean it isn't done at all. I have had to build stuff on the un-level concrete too,but it sure is helluva lot quicker on a flat table and angle plates. I don't think I am better than anyone, but if a company wants to make money on fab work doesn't it make sense to have the tools available to get the job done as quickly as possible?

arvidj
10-18-2008, 09:31 AM
--------------------------------------------------------------------------------

Fast and easy way to square frames and uprights.

Digr,

Where did these pictures come from? They look like a book or site or ??? that I would really like to see more of.

Thanks,
Arvid

smokeshow
10-18-2008, 09:55 AM
What? You want it Square, Level, and Plumb!!! Next you are going to tell me it has to look good and be structurally sound!

ClayKann101
10-19-2008, 12:39 PM
I tack everything then i pull a diagonal i do this when i have to build piers it works great.

Broccoli1
10-20-2008, 06:30 PM
Digr,

Where did these pictures come from? They look like a book or site or ??? that I would really like to see more of.

Thanks,
Arvid

I think he drew up dem sketches.:)

digr
10-20-2008, 10:11 PM
Digr,

Where did these pictures come from? They look like a book or site or ??? that I would really like to see more of.

Thanks,
ArvidThats right I drew dem up

Magnetic Mechanic
10-28-2008, 12:49 PM
why dont you post up what you learned? that might help a few people and it is the point of your thread...

I have learned that using a regular carpenters square is not good enough to square the parting tool in the lathe, but the machinist steel square is the drawer below (lol). this was three years ago now.

To square up a parting tool, line up the side of it with the face of the chuck - assuming your chuck runs true

Hammer
11-02-2008, 11:56 AM
I know Im new and this thread is a little old, but Ive been welding over 25 years and I have a little trick you can do to square with out a square. You need a good tape and something for marking. Mark a place at 12" and on the opposite material youre squaring, mark a spot at 9" that spot to the first will measure 15" if square. I call it welder's math. 12 + 9 =15

Magnetic Mechanic
11-03-2008, 05:58 PM
That is a 3 - 4 - 5 triangle - has something to do with Pathagirus's therum.

lugweld
11-03-2008, 09:19 PM
Its one thing to be able to start off square, but its another keeping it that way. Proper tacking methods by just using enough to hold firmly yet not warp it, particularly on thin gauge materials is key. Don't tack one weld after the other, in a series. If its square, tack on opposite corners, allow time for the tack to cool and readjust before going on to the next one. If it is something like a gate, tack the frame first really well, then insert your crossbars, or panels or whatever. Make sure you don't overheat by running a series of short welds then fill back the gaps.

If it isn't square or its odd, spend time studying the key joints, analyzing which ones are supporting to the stucture and tackle them first. Resquare and proceed to the next most critical joint.

If you use a mig, you may want to learn how to "pulse" the welds until you are comfortable that everything is staying cool enough to hold shape.

Yes! to the Bessey clamps, although one of mine seems to have somehow gotten out of shape a little.

Remember, generally, when you are squaring, you are doing it three dimensionally, not just on the side that you are facing. And recheck all planes after welding. Tubing can twist, particularly this imported steel from Turkey. Make sure you start off with a straight piece too. Plate has dives and warps, unless is is machined or ground. Sometimes good metal can warp from improper storing and support until it is used.

Even if your table is square, and straight, if it heats up on one end while welding, it will exand and make your weld out of square when finished.

To sum it up, check and recheck, then tack, straighten, check and recheck, then weld the sucker! But check and recheck along the way. If you goof, I found a plasm cutter is the best remedy for cutting out a bad welded joint without doing damage to the surrounding area by too much heat and will allow you to straighten the other sides.

paweldor
01-11-2009, 06:40 AM
I have to pretty well agree with Fat Bastard on both his posts. Sums it up pretty good.

How to build things that are square comes with experience. You learn what to tack where and which direction to weld what and in what sequence as you gain experience. After you pull enough of your projects out of square when you weld them up, you kind of figure out what to do to keep everything where it is supposed to be and how to fix it if you mess up.

Ditto. When in doubt, use the WAG method. (wild a\$\$ guess)

paweldor
01-11-2009, 06:41 AM
That is a 3 - 4 - 5 triangle - has something to do with Pathagirus's therum.

I use this quite often, only good for one corner at a time though.

ol' Stick Guy
04-12-2009, 09:30 PM
3 4 5 thats the way see? Pythagorean Theorum as it applies to a right angled triangle 3 and 4 are your legs and 5 is your hypotoneus aslong asyou use equal ratios ie.12, 16, 25 (which is 3, 4, 5 multiplied by 4) you will get a true square unless you are welding boomerangs

MarkBall2
04-13-2009, 12:11 AM
I saw a video on You Tube about keeping a frame square. What I got out of it is if you want it square, weld the longest bead first. Then move onto the next longest bead. Shortest bead last.

The instructor said the metal heats & shrinks as it cools. If you weld the longest bead first, then shorter & shorter beads, the shorter beads will pull it back square.

Maybe I have that reversed, but I couldn't find the video. I'll keep looking, was posted someplace in the past couple months though.

Fat Bastard
04-13-2009, 02:46 AM
Not all fab work is done to that close of a tolerance, but that doesn't mean it isn't done at all. I have had to build stuff on the un-level concrete too,but it sure is helluva lot quicker on a flat table and angle plates. I don't think I am better than anyone, but if a company wants to make money on fab work doesn't it make sense to have the tools available to get the job done as quickly as possible?

What is "this company" making? Half the stuff I fabbed last year would not fit on a table let alone in a shop. and the stuff that fits in the shop would destroy you ground flat table.

When I was welding for Uncle Sam we had some nice tables and the parts I was making has tolerances of +- .005 on some most were +-.030 but they were paying dearly for that kind of work. Much of the work in the end ended up in a clean room with no tales at all.

Nice thoughts you have but like Jim said great big world out here and your and my experience don't amount to a hill of beans in the end.

Always somebody out there building the same sh!t with less because that's what he's got.

Fat Bastard
04-13-2009, 02:58 AM
I'm surprised that I didn't hear anyone specificly mention using a bubble level to fab things up square.

For those of use without granite reference tables or blanchard ground steel table tops, a level works wonders.

Level, square, and plumb each piece of the assembly as you tack them in place. If the first horizontonal member is level, the first vertical member is plumb, and both are square with respect to one another, then all subsequent pieces can be assembled relative to the first. If you've cut everything accurately to the correct lengths, then the resulting work will be right on.

Lots of small tacks are better than a few big ones. Each tack introduces some shrink or distortion, so keep them small. Use lots of tack welds to prevent the finish welds from stretching the tacks.

Keep your welds as small as possible. Big welds make for big distortion. Most people(myself included) massively over do it when it comes to weld size. Bigger may make for stronger joints and better feelings about the work, but it makes for lots of distortion too.

For structures made from angle iron, I usually tack the right angle corner(the bottom of the 'V' in the angle iron), with a spacer create some root opening and room to move the piece around. Then tack one corner, level and/or square the perpendicular direction, and make a third tack weld on the other corner.

Comment on this is level and plumb only works if you are working on something level and plumb to begin with???

When building a fence the posts need to be plumb and the horizontal members neet to be level, but when working off a table I never use a level, the minute you brake out the level the table is never level. :blush:

Fat Bastard
04-13-2009, 03:02 AM
I saw a video on You Tube about keeping a frame square. What I got out of it is if you want it square, weld the longest bead first. Then move onto the next longest bead. Shortest bead last.

The instructor said the metal heats & shrinks as it cools. If you weld the longest bead first, then shorter & shorter beads, the shorter beads will pull it back square.

Maybe I have that reversed, but I couldn't find the video. I'll keep looking, was posted someplace in the past couple months though.

Yes you got it reversed.

Shortest and quickest weld first! then go to the opposite corner and do the same check for square, and make it square then move on.

MarkBall2
04-13-2009, 11:10 PM
Thanks FB, I thought I was wrong after I re-read it. Short side first, then long side. Use the short side as a hinge.

Ironmower
04-14-2009, 09:14 PM
Just a few thoughts, that I didn't see; cross taping works great also. The comment on the hacks, at first upset me alittle and then I reliezed that most of us that do fabricate professionally are AHHHHHHHHH how to put it KNOW-IT-ALL A\$\$HOLES!!! Hell I ain't afraid too admit I'm one to sometimes!!!!! I mean this as a complement, Ironworkers, welders & fabricators are some of the most flamboyent people I've ever met and was proud too do so! I've built several AHHHHHH what you call'em Dirk "hack" tables (sorry can't post smileys yet!)..........These are used to fab handrails and such, one was a 20' x 5' x 5/8" with a 8" channel frame & 10 4" x 4" x 3/8" angle iron legs. I fabbed it on cribbin' on the floor upside-down. I made saddles & wedges I used to "pull" the plate too the channel. Once tacked, I staggered& stitch welded.......The legs had a 5" x 5" x 3/4" plates with a 1 1/8" hole.........I flipt the table over with the overhead, set in place and marked the holes, then moved it out of the way.........Drilled and installed 1" x 6" anchor bolts, bolted to the floor tight, put another nut on the bolts and set the table on them........And from here we set-up are sight-level and was able too dial it within a 1/16"...........I agree this is no Machinest table, but its more than adequite for my kinda fabbin'......YEHH by the wayyyy you don't weld on your machinest table doooo-yaaaaaaaa?

AaronL
08-11-2009, 11:19 PM
Does anyone use lasers for squaring or measuring on large jobs?

lotechman
08-27-2009, 11:22 AM
Does anyone use lasers for squaring or measuring on large jobs?

I have found that a good quality builders level works much better than lasers. The dot ends up too large to determine where you are other than plus or minus an eighth. The builders level takes two people and much patience but it seems most effective.
I use fine string for lengths over 20 feet. I have replaced the string in my chalk line with some strong crotchet thread. It creates a very thin line but does not load up with chalk as easily as the fuzzy thick carpenters line.

On very long lengths thin wire is best. In one shop we had a shop made winch with a drum about ten inches in diameter ... much like a fishing reel. We would clamp the wire end at one end of a bridge beam then with the fishing reel clamped at the other bring the tension up.

You can get crazy with accuracy and waste time and money when it is not required. Each job is different.

DSW
08-27-2009, 03:11 PM
As far as lasers, I have used them frequently to set column base plates and so on. The one we use is +/- 1/64" in 100'+. It's not a visual laser however. You need to use the receiver to locate the beam. It will also do plumb if required.

As far as square on a large site, I've used a transit or theodolite to locate columns on complicated jobs.

Fat Bastard
08-27-2009, 08:57 PM
Use angle plates. You can't really build anything square without them. Depending on what you are building you will always have at least one axis held square. For example if you are building something flat on the table (note: fab tables should always be blanchard ground, or at least some other machined surface) the table will hold one axis square, while the angle block will hold the other. To be efficient at fab work you have to have the tools. Any fabricators tool box should have angle plates, v blocks, and other machinist tools, without them you will get stack up in a hurry.

I tried to set that beam on the table the other day to weld another beam to it square but the table collapsed:laugh::laugh::laugh:

This line of thinking Dirk works for parts you can fit on a table and pick up with one hand.

But when we are talking about fabing the building you are going to fab in all that Blanchard ground, machined table business goes out the window.

The beams I worked on last week were 24x146 and 36x300 The 36" beams needed two 150 ton cranes to set in place. So the size of what you are working on plays a BIG (pun) roll in the tools needed.

William McCormick Jr
08-28-2009, 10:46 PM
I tack everything then i pull a diagonal i do this when i have to build piers it works great.

That is a good idea, you always have something laying around. Or the weld table itself to tack it to.

Sincerely,

William McCormick

AaronL
08-31-2009, 09:36 PM
I have found that a good quality builders level works much better than lasers. The dot ends up too large to determine where you are other than plus or minus an eighth. The builders level takes two people and much patience but it seems most effective.
I use fine string for lengths over 20 feet. I have replaced the string in my chalk line with some strong crotchet thread. It creates a very thin line but does not load up with chalk as easily as the fuzzy thick carpenters line.

On very long lengths thin wire is best. In one shop we had a shop made winch with a drum about ten inches in diameter ... much like a fishing reel. We would clamp the wire end at one end of a bridge beam then with the fishing reel clamped at the other bring the tension up.

You can get crazy with accuracy and waste time and money when it is not required. Each job is different.

Good advise, I appreciate it. I agree that you can waste lots of time trying to get things accurate, it's really hard too when your floor isn't perfectly flat. for my first "customer" in my shop I didn't want to turn down the chance to make money, but I built him a box trailer from a used utility trailer. the trailer was warped from usage and it made it really hard to get everything to look decent, not to mention square.

Good lasers will not blur out like most. I have access to high quality lasers, which will be the same size for as long as you can see them.

thanks again

AaronL
01-22-2010, 09:56 PM
I just wanted to give an update. I just used a laser to help build my samurai roll cage. It worked very well. In this instance, a builders level wouldn't have worked, because I was trying to create a line on the front floor boards for the "A" pillar tubes, so the transmission tunnel would have interfered with anything solid. It was one of the cheaper non-self leveling type so I could move it to where ever I wanted. It had a magnet on one side, coupled to a tube clamp, it gave a great reference line across the vehicle to measure from.

crazycolo1
06-26-2010, 05:02 PM
Don't let the title fool you. Starting at 1:10 to the 5:00 mark he does a good job explaining the sequence for welding corners.

gdf_77
07-13-2010, 10:07 PM
I have found that measuring the diagonals and getting them to be equal is the simplest. I will usually tack it up with a carpenters square (which are rarely correct) to get it close, then take my cross measurements, then take a long pipe clamp or come-a-long across the long dimension remeasuring until the diagonals are the same. Then if the frame fits on my table tacking it down to the table to hold it true. I have used this method on everything from a 12"x12" table to a 150' long slat conveyor.
This thread goes to prove "that there is more than 1 way to skin a cat". When it comes to a fabricating table, if you need to have it machine ground then you are doing some pretty technical stuff. To me, in regards to most of the fabricating I have seen done in this world, it is unneeded. Simply taking your time, taking pride in what you do and making sure things are right will out "fab" a perfectly "true" table any day. IMO. But to each their own.

William McCormick Jr
07-15-2010, 05:18 PM
Don't let the title fool you. Starting at 1:10 to the 5:00 mark he does a good job explaining the sequence for welding corners.

The Twilight Zone that is where I weld everyday!

He has about the right procedure, but the reason the outside does not close up is because it has no strength because of the structure of an inside and outside corner.

Sincerely,

William McCormick

pirana
10-16-2010, 05:16 PM
Don't know why it hasn't been mentioned yet, unless I missed it, but I frequently tack a temporary brace on whatever i've fit up to help keep it square until after it's welded out.

1_black_z28
12-16-2010, 09:29 AM
You mean you guys just don't eye-ball it!?

:D

oxygen454
12-20-2010, 12:53 AM
On small projects a square is good. I usually square one corner and then fab the rest. Bigger projects, I use the 3,4,5 system and / or measure corner to corner. When I am happy, I tack a piece of angle to at least two corners so the welding heat does not make the frame move out of square.

As mentioned, tacking opposite corners is a good way as well. Then you can still square the frame after tacked.

Postman11
05-23-2011, 12:49 AM
I construct a lot of foundations from angle iron. Sometimes they are built in place. An easy way I keep the mounting surface flat is by stretching a chalk line string across opposite corners. With the intersection of the two strings at the center, it is easy to determine if all corners are in the same plane. A flat surface is determined by lifting or depressing one of the strings. If the other string yeilds the surface is out of plane. It also offers an easy visual reference during fit-up and welding and does not require a table for assembly.

ar15is223
06-21-2011, 05:47 PM
http://www.coolmath.com/reference/geometry-trigonometry-reference.html here is a link that explaing the Pythagorean theorem and some trigonometry. There is a lot of usefull information that can be used to square up pretty much anything. Also in the last catalog i got from cdcotools.com there was a good table of trigonometric formulas that are verry straightforward to use

PanelDeland
07-17-2011, 01:48 PM
I'm no weldor.I'm a maintainence mechanic that ocassionally tacks crap together.I do however do quite a bit of mechanical layout and have worked as a layout man for "REAL" weldors.I find that the best trick in my bag is to always do the best work I can.I usually try to get much better accuracy than is required(time permitting)so that I have better experience to get it right when it really counts.I think most of it boils down to experience and if you ain't doing it you ain't learning it.I also agree with the learning curve comment.It'll get flatter but after 35 years mines still pretty "Humped"