Bridge Crane build

[Dabbler]

To minimize alignment issues, you might consider a veeway in the middle of your roller, which mates to a 3/4" X 3/4" X1/16" angle on the diagonal. Many bridge cranes use this to eliminate binding as as the bridge goes off perpendicular, the roller tries to climb the veeway instead of binding. This is especially important if your trucks are unpowered.

 

[rabler]

To minimize alignment issues, you might consider a veeway in the middle of your roller, which mates to a 3/4" X 3/4" X1/16" angle on the diagonal. Many bridge cranes use this to eliminate binding as as the bridge goes off perpendicular, the roller tries to climb the veeway instead of binding. This is especially important if your trucks are unpowered.

That sounds like an excellent idea. Thanks

 

[rabler]

Yet another rendition. Just mulling through this. As always, skip over it if you're getting bored!
This one uses nuts on either end of the axle to preload the taper bearing into the truck frame. That would allow the roller to be adjusted axially for alignment.

Orange are grease seals, dark blue is the taper bearing. Light blue is a bearing nut (32 TPI). Those items are off the shelf.
Big green roller is pretty easy to make. Green axle a little more complicated. The black band is 32TPI threads on either end even though only one side is shown banded. Both ends of the axle have a stub with hole that could be used to attach a pinned shaft for a drive motor as a future possibility. The yellow hub would take some care to get bearing and seal fit surfaces. The grey bushing just under the nut is there to give the outer grease seal something other than threads to seal against.

I've cleaned up the frame a bit, added the end plates which are the contact points at the end of rail stops.. One feature I'm trying for is to have enough open area on the top end of the trucks that a roller could be inspected or even removed without dismounting the entire bridge first.

I've left the side guide roller in the drawing, but I like the angle iron notched roller as a guide. At one time many months past I'd thought of a guide strip (rectangular) on top but didn't get it into any of the CAD diagrams. So even if there are a lot of renditions, it is a good way to keep up with the details for me.

 

[rabler]

For a point of reference, I have a little over $4k into this so far. Much of that is steel, about $2400 for the two rails and bridge plus some for cross bracing. Was about another $1k for the 80 ft of 4x4 square tube that make the supporting posts. All that plus about $900 for a mag drill and annular cutters. I'm ballparking another $1k to actually finish it out, that is probably a bit on the low side.

I'll need a length of 4" round stock for the main rollers and bearing mounts. Probably use 4340 rounds for the axles. The bearings, seals and nuts are about $60 per axle end (so times 8 sets) if I use McMaster pricing. I'll probably check my local bearing supply house for comparison. Much of this stuff is pretty common car axle type pieces so I could check my local NAPA too.

 

[dkemppai]

For a point of reference, I have a little over $4k into this so far. Much of that is steel, about $2400 for the two rails and bridge plus some for cross bracing. Was about another $1k for the 80 ft of 4x4 square tube that make the supporting posts. All that plus about $900 for a mag drill and annular cutters. I'm ballparking another $1k to actually finish it out, that is probably a bit on the low side.

I looked at a few bridge cranes that were 24x40 that could be commercially purchased. $30K for a chinese import, and closer to $50K for a domestic product. This is just a push crane, 2 ton. That money didn't include installation, or freight IIRC.

The one I'm building is going to be around $5K with it when it's done. But that includes some extras (with ebay finds), like a chain wheel driven gantry movement...

Fortunately, I have a mag drill at work that NEVER gets used that I can borrow...

 

[rabler]

I looked at a few bridge cranes that were 24x40 that could be commercially purchased. $30K for a chinese import, and closer to $50K for a domestic product. This is just a push crane, 2 ton. That money didn't include installation, or freight IIRC.

The one I'm building is going to be around $5K with it when it's done. But that includes some extras (with ebay finds), like a chain wheel driven gantry movement...

Fortunately, I have a mag drill at work that NEVER gets used that I can borrow...

That puts us pretty close to the same cost for similar size/capacity cranes. The price of steel has varied significantly over the last few years! I didn't price anything new, but I did look at several used cranes that I could have picked up locally. None of those where close to the right size to fit my footprint, lot of them where in the 12' x 16' ballpark. I really want the utility of something that spans all of the machines and my workbenches. Being able to pluck a 300lb rotary table up and move from bench to mill to storage rack.

 

[dkemppai]

Being able to pluck a 300lb rotary table up and move from bench to mill to storage rack.

I'm getting to the point I don't even like picking up a bag of readymix concrete any more. Having a tractor, I don't pick anything up by hand that I don't need to. I even use the tractor as a wheelbarrow when doing yard work, lol. It's as they say, Work smarter, not harder!
I Just need to balance making things easy with getting at least some exercise...

Considering how different our two designs are it's interesting how similar the cost will be. Then again, for the same area and lift capacity we're going to have about the same amount of steel in the air, and with steel priced per pound it makes sense the costs should be similar.

Breaking down the cost a little, what do you think you'll have into your trucks when done?

 

[rabler]

I'm getting to the point I don't even like picking up a bag of readymix concrete any more. Having a tractor, I don't pick anything up by hand that I don't need to. I even use the tractor as a wheelbarrow when doing yard work, lol. It's as they say, Work smarter, not harder!
I Just need to balance making things easy with getting at least some exercise...

Considering how different our two designs are it's interesting how similar the cost will be. Then again, for the same area and lift capacity we're going to have about the same amount of steel in the air, and with steel priced per pound it makes sense the costs should be similar.

Breaking down the cost a little, what do you think you'll have into your trucks when done?

Ugh, I use to throw around 80lb concrete bags easily when putting in fence posts, now I refuse to buy anything bigger than the 60's and struggle with those. I've been known to refer to my tractor/load (John Deere) as my big green diesel powered wheel barrow.
Haven't come up with a suitable nickname for the excavator. Probably something like 'the little yellow shovel'.

We have the horses so hauling hay and water buckets, not to mention the 1/4 mile walk each way to the barn is my exercise. I try to walk up to the top of the hill in the back yard on my morning trip to the barn. But I've struggled to keep my weight under control since pre-adolescence.

The trucks ballpark using those McMaster prices
bearings $30 (x 8)
bearing nuts $10 (x8)
seals $10 (x 16)
So thats $480 in off the shelf hardware.

Steel for the rest ...
Axles: 4 ft of 4340 1.125" $96 (onlinemetals.com)
Rollers and bearing plates: 3 ft of 4" 1144 $633
12' of A36 6"x3/8" for truck frame side plates: $150 (already in hand)
6" of A36 4.5" x 1/4 for truck top plates: $50

That's about $1200 for the trucks at the hi end, but I'll probably beat those prices once I start shopping. Of course material cost goes up significantly if I mess up a part, which is going to happen ...

It's not the kind of project that I'm really counting costs too closely. Thinking back I'm sure there's at least another $1k in paint, welding supplies, and nuts/bolts already spent, so with the mag drilll my final cost is probably closer to $6-7k? Still beats $30k.

 

[dkemppai]

Ran the numbers for the trucks here. Probably just a bit under $250 ea for these trucks. That's just buying rollers, heavy wall rectangle tube, and a few bolts and weld nuts. With twin gantry beams, the rollers are almost under the beam so don't need a very big tube.

Probably the biggest thing with the cost of the project is that most of that money has already been spent. So the painful part is over now!

 

[rabler]

Ran the numbers for the trucks here. Probably just a bit under $250 ea for these trucks. That's just buying rollers, heavy wall rectangle tube, and a few bolts and weld nuts. With twin gantry beams, the rollers are almost under the beam so don't need a very big tube.

Probably the biggest thing with the cost of the project is that most of that money has already been spent. So the painful part is over now!

I turn 59 1/2 in July. So I can access my regular retirement rather than a small amount that I put aside to get to retirement age in one of the many IRS special plans that I qualified for working in academia that allow for even younger retirement/withdrawal. But with a good chunk of recent medical expenses and quite a bit more likely, I'm trying to get the rails hung without any crane more expenses til July. @Dabbler 's tracking suggestion means buying 80' of angle, I might try to squeeze that in. Those 40' rails sitting up at working height take up most of the open space in the shop.