Bridge Crane build

[rabler]

Looks like some good progress. Nice new clean steel with fresh paint. I like it!

Bought the yellow paint I used on the boom lift for the actual bridge. Sherman Williams "Safety Yellow".

nice work, @rabler

Thanks, for both the compliment and the advice to date.

That is awesome

Appreciate it, but I'm reserving "awesome" for when I get to use the bridge crane to actually lift something!

 

[extropic]

A substantial, ungainly lift in tight quarters successfully accomplished at home, with no injuries or damage, deserves a big

 

[rabler]

A substantial, ungainly lift in tight quarters successfully accomplished at home, with no injuries or damage, deserves a big

Appreciated, but I do have the other side to do yet. So I'm going to dodge any applause to avoid cursing myself

 

[extropic]

Appreciated, but I do have the other side to do yet. So I'm going to dodge any applause to avoid cursing myself

I hear you. I have high confidence that you will save me from being the jinx by accomplishing the rest with equivalent poise.

 

[rabler]

Put up the other rail today. One heart stopping moment when rotating the beam and one of the chain links made a popping noise as it shifted/twisted. Lots of torque with 20' lever arm and only a few links between the top of the beam and the boom hook. Otherwise without incident.

Now I need to work on the end braces for the rails. Then construct the bridge end trucks, and the bridge beam itself. Likely several months of work. I'm hoping to get the end braces for the rails done before heading back to the Mayo the third week of June. Schedule after that will depend on what the Docs and I decide wrt the Crohn's & bowel, i.e., whether or not surgery is warranted.

 

[Boswell]

one of the chain links made a popping noise as it shifted/twisted

Gotta love those adrenalin moments.

Great to see you continuing to make good progress.

 

[rabler]

Got one of the two end braces set. I'd guess the end braces weight about 150 lbs each. Hoisted the rail from the middle on a small gantry crane, then tilted the end brace enough to get one bolt in the high end. Use a block and tackle on the other end to raise it. Did run into an unexpected clearance problem with one bolt in the upright conflicting with the end brace. I slotted the end braces 1" each end so that I can adjust the two rails to be parallel.
Also, put up one set of turnbuckles under the rails to see what that looked like.

 

[Dabbler]

so... what are you doing to prevent racking along the bridge axis? Perhaps a diagonal member on the end braces?

 

[rabler]

so... what are you doing to prevent racking along the bridge axis? Perhaps a diagonal member on the end braces?

The end brace to posts will also get diagonals, you can see in the first picture the eyes are welded on for those. While not in place for the photo I already tested a turnbuckle there to verify fit as the end brace diagonals worked out to be slightly longer. I don't expect any forces to drive racking in the plane defined by the two rails, that hopefully should be sufficiently rigid based on the other two planes.

Keep in mind that this was only one of two end braces installed so plenty of work to do yet. Everything is fairly stable under it's own weight just based on the posts, without any cross bracing, so the cross bracing is for dynamic forces caused by moving the bridge on the rails, and the load along the bridge. In order to square everything up, I'll want to start by removing or loosening the turnbuckles to avoid any forces there, then level and square everything based on the bolts at the base of the posts without any force from the turnbuckles. Then tighten the turnbuckles in opposition, without distorting the frame. Then a final check of square before grouting the post bases. I'll want the bridge beam in place for that, and the trucks and bridge beam are yet to be fabbed.

I've thought about using 1/2" x 1" rectangular pieces to replace the turnbuckles, but frankly the turnbuckles are not that expensive and are rated for 2000 lbs WLL.

 

[rabler]

Got the other end brace hung. No pictures of the process, but it was challenging due to the large and heavy machines on that side of the shop. Used the tractor to hoist the end brace about 15 feet away from the wall it eventually ends up adjacent to. Then used rope to hang each end of the brace about a foot below the rail. Using a block and tackle, that rope was then walked to the back wall in 1-2 foot steps. Tedious to do while on a step ladder, and certainly less than ideal.

Now I'll need to start working on building the trucks that hold the bridge. These are going to take a fair amount of work to build. The option of adding a coupling mechanism between the two trucks and possibly a motorized drive makes the trucks more complex to build. These may go through an iteration or two, especially details on the axle and roller assembly as that is fairly complex with the bearings and seals. The CAD pictures are dated, notably I narrowed the roller some time ago.