Shop Entrance Boom

[Sandy]

After loading and unloading serveral heavy items lately I found out the ole body just can't do 200lbs plus anymore like it did some many moons ago. I decided I needed something to help out a little. Here's what I came up with, a boom/cherry picker at the big door. Built low enough to reach through the door and just into the shop a bit.

All existing materials, the only thing I had to buy was the long ram jack. I was lucky enough to have some 3"x3"x1/4" wall rectangular tube. Not quite long enough so I pieced that out with 2 foot of 2 1/2"x 2 1/2"x 3/16ths" tube. For the top piece it swivels on I had some 2 inch 1qtr wall DOM. I used some 2 inch schedule 80 to slip over that. The main stem of the base and round plates were from some transformer cribbing that I kept around. Cut two pieces and put them together for one longer section then used the end pieces for the circular pieces I needed. All other little doodads were either cut off something else or fabbed from materials on hand. Still need to buy one 1" bolt for the boom hinge tho. Got a piece of one inch solid stock in there temp (yeh temp)..

Bear with me on the pics. Hope they are sized right. I don't do welds good enough to show details of those but the pics give the overall concept. I'm also heck about priming or painting the same day I get a ch8unk welded up too, so that doesn't leave much to show on the welds. The main boom pic had some major sun bouncing off the lense.

Maybe a couple three posts here. Hang in there.

[Sandy]

So these are the pice parts setting around. The main boom/arm, the riser /support post, the jack, ties to the shop wall, the mounts that tie all that to an existing yard light poured in concrete years ago.

This DSL modem is having serious upload issues so this is taking a while.

[Sandy]

Well it's only letting me do one at a time.. Sheesh. Sorry about that.

We'll do this a bit at a time I guess.

[tanglediver]

Take your time Sandy, looking good!

[Sandy]

This ain't woking. I appologize. Go change modems maybe.

[farmersamm]

No rush. It looks good so far

[Sandy]

New modem isn't making much difference.

It's like it is hitting a blank wall on uploads then a tiny burst gets through then another two minutes of blanks wall, gads. Gets worse as the evening goes on.

So if I get three here, better call it quits. Just takes to dern long. Interesting that I can open other tabs and cruise the internet while waiting on this???

Okay done for now. Won't bother you guys any more with this stuff.

[Sandy]

Forgot to say the main riser is crooked setting on flat ground because it was built angled for the slope of the slab it bolts up to.

This thing goes from 3 foot off the slab to about 12 foot 6 inches in the air.

[farmersamm]

I saw the angle in the pics of it sitting in the back of the shop. Beats messing around with washers and shims when you mount it to the angled concrete.

[mark8310]

Looks good Sandy. Just be aware, the safe load on this will decrease, as you go from the vertical down to the horizontal; theoretically, you could safely pick a load out of your truck, but as you were lowering it to the ground ....

[DSW]

Originally Posted by Sandy

Forgot to say the main riser is crooked setting on flat ground because it was built angled for the slope of the slab it bolts up to.

This thing goes from 3 foot off the slab to about 12 foot 6 inches in the air.

Yeah, I thought that was one F'd up support column for the garage roof at first. WTF why take a pict with THAT in it??? It makes more sense now.

[Sandy]

One more even tho I said I was done, . If this works one more.

It is about two inches lower than the doorway when level so it will swing inside the shop about six feet. It is eight feet long so it jus almost reaches center of the door way then cuts an arc through the shop.

[farmersamm]

Have you put any weight on it yet in order to see how the upright support behaves once the crane is swung offline with the (flagpole?).

I mean an angle not paralel with the front of the garage. Swinging into the garage, or past the pole out onto the driveway

[Sandy]

No load on it yet, other than my old aging butt. There is some initial springyness there then it comes up rock solid. Eventually I'll start loading it up to some point I feel comfortable. I'm hoping for the 700 to 800 pound range??

[Sandy]

Originally Posted by mark8310

Looks good Sandy. Just be aware, the safe load on this will decrease, as you go from the vertical down to the horizontal; theoretically, you could safely pick a load out of your truck, but as you were lowering it to the ground ....

So if something fails it'll be at the point where the boom is level?? I bought the lightest jack I could get but it is still 3 tons. I was banking on the jack to be one limiter, that still leaves the end at one ton. I don't think it'll do one ton buy a long shot.

[farmersamm]

Maybe as you test increasing loads, see if there's any deflection of the upright. And see how the deflection changes as you pass the brace against the house on the way to being paralel with the pole, and beyond.

I think if you check it at all angles thru the 180 degree arc, you'll get a good feel for how it's going to handle the weight. There's a lot of force on the upright in a crane like this.

It will probably be fine, but maybe at a lower weight than you anticipate. I dunno. It's hard to guess. I second guess myself so much that I sometimes get weird(weirder)

[farmersamm]

A guy that was really interested in helping me understand bracing and stress copied these for me. I hope it'll give you some idea of the stress loads involved by visualizing how the bracing is constructed on these examples.

They really opened my eyes to different ways to brace a crane

[Sandy]

Originally Posted by farmersamm

Maybe as you test increasing loads, see if there's any deflection of the upright. And see how the deflection changes as you pass the brace against the house on the way to being paralel with the pole, and beyond.

I think if you check it at all angles thru the 180 degree arc, you'll get a good feel for how it's going to handle the weight. There's a lot of force on the upright in a crane like this.

It will probably be fine, but maybe at a lower weight than you anticipate. I dunno. It's hard to guess. I second guess myself so much that I sometimes get weird(weirder)

1st I'll need to do some lifting to get an Idea of what a safe load will be, then I'll label it for idiots like me. Next I'll need some point of failure besides ripping the side out of the shop. I lifted 1800lbs with the header of the 16 foot door. I came down 1/2 inch and went back up a qrtr. Can't have much more of that kind of thing.

What I want is to load and unload the generator, things like that. What does an engine and tranny weigh?

[farmersamm]

You ought to be fine then I guess.

[sdonecker]

Based on estimated dimensions the geometry suggests a capacity of 900lbs max given a 3 ton cylinder.

[MoonRise]

Sandy,

You're probably having trouble UPLOADING the pics because your ISP is set up for mostly users downloading things. Upload speed is often much s-l-o-w-e-r than download speed. It gets worse in the evening because everyone else comes home from work and gets on the network and it all slows down from all the traffic.

With that boom being 8 ft long, I don't think your realistic safe lift load is going to be more than 500 pounds if that.

A typical 2 -ton engine hoist ( http://www.harborfreight.com/cpi/cta...temnumber=7620 ) only has a lift capacity of 500 pounds when the boom is fully extended (and that's a 6 ft boom or so, not 8 ft), and the 2-ton lift capacity is when the legs are fully extended and the boom is fully retracted. And that's with an 8 ton cylinder! I don't feel motivated (or bored enough here ) to run some more detailed numbers. You have the bending of the boom, the capacity of the cyclinder, the reactions at the light pole and the house bracket, and so forth.

Ingenious and all, but NOT really made or safe for heavy lifting!

[Magnetic Mechanic]

For those really heavy loads, you could use a chain hoist and outrigger.

[gordon stephenson]

Hello Sandy,
Davit arm looks great by the way, Just looking at the ram position when in the low position there will be an awful lot of strain on the boom ram brackets, It would act better if you can build out the bottom mounting a litte so that the ram is acting more vertically
I'ts gunna save a whole load of back ache !!!
Cheers Gordon.

[MoonRise]

Based on estimating the geometry (scaling with my eyes and finger-widths ), with an 8 ft long beam I estimate the hydraulic cylinder attachment points at 2 feet away from the beam pivot point in both the beam and upright directions.

Worst-case beam load will be with the beam horizontal. That leads to a lift load limit based JUST on the maximum capacity of the cylinder (stated as 3 tons = 6000 lbs) of 1050 lbs.

6000 lbs (max force from cylinder) x 0.707 (geometry factor for 45deg position of cylinder) = 4200 lbs vertical force from cylinder at the cylinder attachment to the beam

4200 lb (cylinder vertical force) x 2 ft (distance of force from end pivot) = 8400 ft-lb

8400 ft-lb / 8 ft (total beam distance) = 1050 lb at beam end

That is MAX and ignores any/all safety factors and is based ONLY on the stated lifting capacity of the 3 ton cylinder. It does not even look at the actual structure (strength, bending, etc).

With a 2:1 safety factor, that max lift is now 525 lbs based solely on the 3 ton force from the cylinder.

But cranes and lifting devices -usually- use a 5:1 safety factor, so your max lift capacity then drops down to 200 lbs.

Take a look at existing commercial job cranes and see the general size/structure for points of reference. Like here at http://www.lkgoodwin.com/more_info/w...ib_crane.shtml

Their 8 ft span jib crane with a 1/4 ton lift capacity (no lifting cylinder, it's just a cantilever-mounted beam) Model # WC200-B1-8-6 uses an 8x6 (wall thickness not specified there, but I'll guess 1/4 inch wall) rectangular tube for that 8ft length and 500 lb lift capacity.

A quick check on another source indicates an 8 ft long 8 x 6 x 1/4 tube can cantilever lift 1000 lbs at the end and -just- meet 'code' (and deflect about 1/2 inch at the end).

Your 3 x 3 x 1/4 tube is much thinner than that. And it's not 3x3 the whole length. Although the lifting cylinder does shorten the lifting distance from 8 ft to 6 ft (if my eyeball guess of the cylinder attachment point of 2 ft is close).

Also, for sizing reference, the above website's ground-mounting pad for a 1000 lb 81 inch lifting distance davit crane is 1/2 inch plate and 16 inches square. It doesn't look like your base plate is that big. http://www.lkgoodwin.com/more_info/s...t_cranes.shtml

Like I said earlier, ingenious and all but NOT for heavy lifting. Hate to see you bend your light pole or rip the mounting bracket out of the house or otherwise OOPS something. Never mind possible injuries if something lets go suddenly.

Why not a typical 2 ton engine hoist? You lift something up in the driveway and then wheel the hoist into the garage and then lower the object. They are only about 6 ft tall when you don't have the boom extended and raised, so it should clear your garage door. About $200 new from H-F or TSC or such, less on sale and with a coupon.

[daddy]

Sandy, I like it.

I think MoonRise has some reasonable concerns about the capacity. It may need some reenforcement to make it do what you want. It is hard to go by pictures, but I wonder about how it is attached. You have one he!! of alot of leverage there.

Thanks for posting, and please continue to keep us updated.