Mini gantry crane

[jack707]

Look guys we have shielding gas AT THE SITE we so that's NOT THE PROBLEM, THE PROBLEM IS its a weld that does NOT go as deep as smaw. There good in body shops.

 

[Jim Timber]

Shielding gas at the puddle, not at the job site. SMAW is a simpler process with less ancillary equipment needed. A power supply, some leads, and a box of rods = good to go! It also performs better in outdoor environments - where you don't have wire liners, spools, guns, feeders, and a power supply exposed to rain and dust.

Keep grasping though.

 

[Coyote machine]

Could load it up and roll it over a pebble and see. Polyurethane might accommodate small pebbles.

Personally I'd load it at least double of the 880 lbs and lift 1 inch, bounce on it, shove it, try to see where it's flexing and brace accordingly.

Ignore the purple brace on the red/white juncture, I drew the pic but now I don't think it provides anything. The load on those 1/2" bolts is a tiny fraction of their capacity.

The rolling legs could have a fold-up brace that swings down and double-pins at center for when you travel it. Or maybe if you ever have a real heavy load just bolt a 2x4 across from leg to leg (at that time). You might get a handle on this by rolling it over a pebble with 2x or 3x 880lbs.

And you could hang a shower curtain from it. :thumbsup: Don't need a towel with that blow-dry.

I was thinking since I first saw your setup that a chain at near floor level that could be attached when you're in process of moving a load, in advance of course of actually moving/lifting it, could span the two legs and make it so they can't spread apart at the crucial points of moving your load. This could easily be run over by the tractor or truck or whatever, before attaching it to both sides, then again dropped to the floor before exiting the bay with the load already in place in the truck bed or on your forks, etc.
I'm by no means any kind of expert on cranes or welding of any type- just trying to contribute something possibly useful.
Here's a link, just for looking at to see what is done in a 1 ton gantry crane, in case any of the design could be useful to the OP in his application. Please note the leg base supports; granted they aren't able to be incorporated into your crane, but might help in the overall discussion.

1 ton Capacity Telescoping Gantry Crane

 

[robstaples]

I hate to interrupt a weld discussion, but I was hoping for some comments on my tentative solution. I mocked up to weld weaknesses with bolts and steel. The top of the legs would have L steel (angle Iron) 3x4 or 3x5 by 7" ( I used a small sample for picture) and bolt thru the 3x6 in two places each plate. There would be 2 on each side -- 4 total. The tee joint weld would have bolts approx to where the black dots are on the paper. I will reevaluate the top of the tee during the drilling of the bottom. I have a 3x3x1/4 stick the if I add tabs to the bottom of the legs- near the caster, I would put in place when ever I am moving a load, otherwise it is stored attached to the outside of the left leg.
Thanks. rob

 

[robstaples]

Coyote Machine, Sorry , we were typing at the same time. I think my rigid 3x3x1/4" square tubing will lock the legs sufficiently when needed. see above Thanks

 

[Coyote machine]

Coyote Machine, Sorry , we were typing at the same time. I think my rigid 3x3x1/4" square tubing will lock the legs sufficiently when needed. see above Thanks

No problem, just trying to throw out some ideas. Wouldn't a chain be more useful, because you can throw it under a tractor and connect to each leg, whereas something like a stick from the legs won't be able to be put in place if a tractor, truck or dolly is already between the legs area in question?

 

[Jim Timber]

Bolting those connections would be great.

The chain suggestion is also a good one, but I'd first verify the cross beam isn't twisting causing the observed spread.

 

[Coyote machine]

Couldn't you also go out to one side, on each leg, away from the OH door opening, also supported by a locking wheel to give additional support? This single horizontal leg could then have a welded or bolted or both section going at a 45* angle back onto the main leg, without any of it being in the way of lifting/moving loads. It would be a 1/2 of the support structure shown on the gantry crane I linked to, instead of the double triangles used in that crane support it would be single ones on each leg.

 

[robstaples]

I'll add the bolts and steel L's and the 3x3 is bidirectional support versus a chain - unidirection support. But I have chain, so I'll see as the situations arise. I should mention welding justified a new welder, bolting just a new drill.bit:laughing:

Thanks all, rob

 

[Jim Timber]

Welding will pay for itself down the road. Need to keep your digits intact for that to work.