Input on how to repair revolver crane

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10-07-2014, 13:58
thvigil11

Input on how to repair revolver crane

So I've been slowly working on this Colt New Service I got some years ago. The overall finish was rough. Cylinder spun freely, trigger bound, barrel was used to drive tent stakes, and a few bits and pieces were missing. The good parts were the original grips, the frame was solid and it cost me next to nothing. Right now I'm into it for about $150 and my free time. So far, I've repaired all the internals and got the timing in order. I have a newer barrel that's going to work out great. (got delivered yesterday). Once I'm done, I'll probably look to refinish the entire thing. I'm thinking of Zinc Park and then it will look like a WWII rebuild. It will also hide some of the scratches and marks in the metal.

What's left to do is repair the crane. I've looked for a replacement online, I might have better luck sourcing a chinese leprechaun. The bearing surface on the crane looks like someone took a horseshoe rasp to it. If i reuse the crane, I will either need to buildup and turn down this area or cut and replace the bearing surface. Of course this will affect the cylinder gap, but seeing as how I am replacing the barrel, its already something I'm prepared to address. So my question to my fellow tinkerers is.

1. Build up the area and machine back down?
A. Mig
B. Tig
C. Braze
2. Machine off the entire bearing and slide on a new bearing? Again multiple attachment methods

I am concerned about putting too much heat into it. Cranes do transfer the recoil load to the frame, but I think it is purely linear, (no torsion). I could heat treat it after the welding. I feel like the replacement method would be less temp into the part. I also thought about milling out a block of AL to act as a heat sink. So which method would be preferred here. Or is there another way that I am missing right now?

http://i1079.photobucket.com/albums/...psf2bf8bc2.jpg
http://i1079.photobucket.com/albums/...pse3a95fb5.jpg
http://i1079.photobucket.com/albums/...ps4609b043.jpg
10-07-2014, 20:33
BPTactical

TIG or replace
10-07-2014, 20:53
skullybones

Quite the mess was made of that surface. Oh well.

From a machining standpoint I would do the following:

1. Cut away the original bearing surface using a mill, but this will require the ability to perform a circular interpolation with the mill. Barring that ability, a lathe will work with an offset tool that fits in the "groove" created by rotating the part. For the latter, figuring out how the chuck the part will be the crux. --> machined soft jaws might work.

2. Gage pin the ID of the cylinder bearing surface. Once this measurement is obtained, turn and bore a new bearing surface that is a very tight slip fit over the male portion of the crane, and a loose slip into the cylinder. The tight ID will help to keep the piece perpendicular. Make this piece thicker .030" thicker than needed to accommodate re-machining later. Without blowing out the ID of this machined part, apply a heavy chamfer to allow filler rod a place to go during TIG welding.

3. Have a TIG welder mate these two parts. I'm out my element on this process, but I will recommend that this be done by someone well practiced in foot control for thin material.

4. Re-machine the new bearing surface to achieve a flush fit with the cylinder. Check tolerances with cylinder and crane installed. Rinse and repeat as necessary to achieve the desired tolerance while locked up.

There may be a better way, but this is what I think will get the outcome you desire.
Jared
10-07-2014, 20:57
skullybones

Quote:

Originally Posted by BPTactical

TIG or replace

There's this as well. It could very well be possible to build up what you have, and re-machine the weld. Tough to say without seeing it in person. But again, welding isn't my specialty.
10-07-2014, 21:32
thvigil11

Kinda what I figured. The machining ain't an issue. Time and patience there. Pretty rusty on tig , but best friend is a champ. I'm leaning towards the cut and replace method, seems the best way to ensure consistent surface properties of the bearing area. Just hoping someone had a genious idea I hadn't considered. Especially one that didn't involve JB weld.
10-08-2014, 12:12
skullybones

Right on dude! Take pictures once it's all together.
12-17-2014, 22:10
skullybones

Any updates to this Colt resurrection?
12-18-2014, 16:04
thvigil11

Quote:

Originally Posted by skullybones

Any updates to this Colt resurrection?

Little by little. Got the crane back into shape. Will get some pics up first of the year.
12-19-2014, 11:04
skullybones

Quote:

Originally Posted by thvigil11

Little by little. Got the crane back into shape. Will get some pics up first of the year.

That's awesome! I can't wait to see how this turns out. I guess I left out one step previously: patience.
Hahaha

Best of luck as you continue this project.