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mike4
02-21-2012, 02:40 AM
With the two recent posts about jib cranes for workshop applications , I have started to give some thought to constructing a 3 to 5 tonne bridge crane for moving things in a small shop I use .
It would need to have a low profile for the trolley and the beams only need to span about 3.5 metres , there is 3metres of space under the ceiling .
Anyone know of links to sites which could help with design , I want to get some idea of the required steel sizes to get an estimate of cost.

Either that or I could wait for one to come up on Ebay or similar sites ,but then it would need to be either cut down or extended to fit the space.

Michael

Chris165
02-21-2012, 07:46 AM
Take a look at Vestil mtg they have a ton of lifting devices. The work area portable gantry is close to what you are looking for. Wallace gantry is another company that makes adjustable gantry systems.

hardtail
02-21-2012, 12:13 PM
SFT has some bridge threads, look for an old one by Pile Buck maybe Buck Pile, there was another more recent on PM but I think it maybe purged already? Look in homeshop or members shop section. Both spans were way bigger than your looking at. Do you have exisiting structural members in your walls or the whole system needs to be built from scratch?

5 tons normally would be a big bridge build but your span might be ok........

My buddy was going to build a 40' bridge setup with semi trailer frame rails, said for the loads they have to carry couldn't see any problem......properly braced together he's likely right.

bob_s
02-21-2012, 12:29 PM
Check out Beamboy 2.2

http://www.engineering.com/tabid/74/Default.aspx

Should give you enough insight into design of a gantry.

davidh
02-21-2012, 01:35 PM
IN THIS PART OF THE WORLD, getting them certified for employee use is one of the major factors. if memory serves me .

mike4
02-21-2012, 10:02 PM
Thanks for the links I have looked at a couple and their designs look usable in my application .
There wold have to be some modificatios to allow for the low height of the building but all should work.
Now I can calculate the steel sizes required and see if the budget allows .
Michael

hardtail
02-21-2012, 11:13 PM
Heres the PM link bridge build, couldn't find the SFT one........

http://www.practicalmachinist.com/vb/member-shop-photos/rosies-shack-187552/

.RC.
02-22-2012, 12:47 AM
Just check that the steel sizes are applicable in Au...

I imagine US beam sizes are different..

Jim Shaper
02-22-2012, 01:10 AM
Overhead cranes are built to a 5:1 safety factor. Mine is built for 2T and it could easily handle 10T. The static loading isn't where the issues come from, it's the ability to handle a dynamic load - like when something shifts. You don't want the bridge beam to twist and buckle because a chain broke or strap frayed and the load rolled.

You also need to consider than when the load is closest to one of the runway beams, your other beam isn't holding half the weight anymore. They need to be sized accordingly for every possible loaded condition.

There's bunches of good info available online, but very few places will actually spec out a beam. Beam Boy is a great application for doing that, but once again, it doesn't account for dynamic loads. You need to be conservative, because this could be life or death.

Getting past OSHA isn't going to happen without an engineer's stamp on the design and likely certified welders working on it. Mine is in my home shop, and I'm not allowed to have employees that aren't related, so that's how I got around it. Your insurance might also disagree with a shop-built crane, so you might want to check into that.

I love mine: it makes moving machines around a one-man proposition. I can rearrange the shop in a couple hours, and my lightest machine is 2400#.

mike4
02-23-2012, 12:52 AM
SFT has some bridge threads, look for an old one by Pile Buck maybe Buck Pile, there was another more recent on PM but I think it maybe purged already? Look in homeshop or members shop section. Both spans were way bigger than your looking at. Do you have exisiting structural members in your walls or the whole system needs to be built from scratch?

5 tons normally would be a big bridge build but your span might be ok........

My buddy was going to build a 40' bridge setup with semi trailer frame rails, said for the loads they have to carry couldn't see any problem......properly braced together he's likely right.
Scratch built , that has its advantages as if I move to another site I can dismantle it and take it with me .
The steel sixes are slightly different to what the US uses but the sites have been very helpful , now to make some money to pay for this project.
Michael