New shop! (was: Multiple buildings, ...)

[rabler]

How did you size the bridge rail? What sort of safety factor did you look at?

I haven't purchased steel yet for the rails and bridge. I used L/600. I found references for L/450, L/600 and L/800 IIRC. I compared that against a 5x safety factor. Pretty similar overall dimensions, I'm running just a bit smaller. The side rails are supported by 4 posts, so the side rail span is only ~ 13'. I assume with a low overhead you're still using top running rails.

At ~400lbs plus rigging, I'm going to try just dragging the bridge from the hook, but I'll add a cross pipe and drive chain if needed.

 

[dkemppai]

I assume with a low overhead you're still using top running rails.

Yeah, top running rails. I just like the safety aspect of having a single uninterrupted beam stuck above the support. No matter what, it can't fall down!

The building has a flat ceiling, and I did recessed lighting (That was actually the cheapest option, although a bit of a pain to put a ceiling around all those holes). The top of the gantry will run only about 1.5" below the ceiling. The ceiling is just under 12ft. The low overhead design came from looking at a single beam rated for 2T over that span. What really bites you is loosing the beam height, trolley height, chain fall height, and in my case the load hook has a block loosing even more height. Then you loose the height of any rigging. In another garage with 10' ceilings and a rail right at the ceiling, that limit turns out to be a lot lower than you think it would be. So, bit the bullet and just doubled the rails. Turns out the beam I was after was available in a 50' beam, and the steel company cut it into lengths for me with only a couple feet of leftover. That does mean more fabricating to get the big chain fall mounted, but that's minor. Even with the double rails, a single trolley could be used on one rail for lighter loads, so nothing really is lost in flexibility.

I might bump the ceiling clearance to 2", but not sure yet. That can be adjusted just a bit as I'll be notching the end of the bridge beams similar to how your drawing shows it.

I selected the beams based on maximum bending stresses with distributed load plus the rated point load mid span and x5 SF. Basically looked at different W beam profiles that gave the best strength and weight per foot in the height limits chosen. Checking the numbers now, and it's a bit better than L/1000. It's pretty stout alright, but honestly upping steel size wasn't much more expensive. And I feel better about it, given my engineering ability!

Dan

 

[rabler]

I might bump the ceiling clearance to 2", but not sure yet. That can be adjusted just a bit as I'll be notching the end of the bridge beams similar to how your drawing shows it.

While I am similarly trying to maximize vertical lift height, I'm leaving a bit more ceiling clearance to facilitate assembly. How are you lifting the bridge into place?

 

[dkemppai]

While I am similarly trying to maximize vertical lift height, I'm leaving a bit more ceiling clearance to facilitate assembly. How are you lifting the bridge into place?

That will be a little bit of a trick. The bridge will go up as two rails and be bolted together in place, the rest of any attached hardware can be assembled in place. No access above the bridge is actually needed. That's been 'baked into' the design from the start. This bridge couldn't be moved into place in one piece.

The rails were a similar challenge for those I used a pair small chain falls. I can drop two ceiling panels and support the chain falls from above the ceiling. Once at height I'll build some 2x6 cribbing to allow me to move them into place. Big GRK screws and 2x6's, etc.

 

[rabler]

That will be a little bit of a trick.

I still need to buy and hang my rails so I'm a bit behind you. I have a tractor w/ loader that will lift about 3000 lbs, so I'll use that to lift things into place. Reviewing my plans I'll have a bit over 3" of ceiling clearance, need 2" to clear the LED tubes.

 

[dkemppai]

I still need to buy and hang my rails so I'm a bit behind you. I have a tractor w/ loader that will lift about 3000 lbs, so I'll use that to lift things into place. Reviewing my plans I'll have a bit over 3" of ceiling clearance, need 2" to clear the LED tubes.

Thought about using the tractor, and decided a couple of cheap chain falls would give better control. I had to wiggle the rails around a bit, and slower was better in this case. One rail had to go up between a wall and a garage door support with only inches to spare, then move over 6 feet.

A tractor and loader will probably be a lot faster!

 

[rabler]

My vertical posts are all bolted to threaded road set in the floor in a way that I can adjust each post. I'll use that to fine tune the height to get everything dead level and then grout the posts for load bearing. Just ordered the steel, so I'll be picking that up next week.

 

[rabler]

I went up in size, so I'll have 4000lbs capacity at L/600. That means I'll be able to lift all of the small-medium sized machines.

 

[dkemppai]

I went up in size, so I'll have 4000lbs capacity at L/600. That means I'll be able to lift all of the small-medium sized machines.

Just curious, what was the percentage jump in cost, going from the 1 ton to the 2 ton?

Moving that iron around the shop can be fun. I greased up the axles on the car jack, and used that to move things around in the shop. It actually works very well for that. It's been handy for rolling beams over too.

A Little progress on the crane here today, just cutting and milling a few fiddly parts for the drive mechanism. I think you'll have yours in the air long before mine done!

 

[rabler]

Just curious, what was the percentage jump in cost, going from the 1 ton to the 2 ton?

Moving that iron around the shop can be fun. I greased up the axles on the car jack, and used that to move things around in the shop. It actually works very well for that. It's been handy for rolling beams over too.

A Little progress on the crane here today, just cutting and milling a few fiddly parts for the drive mechanism. I think you'll have yours in the air long before mine done!

I didn’t ask. I usually price things online, something like metal supermarkets.com. I can usually get a quote from my local supply shop about 2/3’s of that cost. Based on the online price I just opted for the larger size/capacity. It means I can pick up all but my bigger machines. Fortunately 40’ and 25’ were available uncut sizes, So I’ll only trimm off a couple of feet.