Repair ideas!

[Kevinb71]

The pinion in my lathe chuck is augered out and it is difficult to tighten properly. It is an older Logan Powermatic chuck. The rest of the chuck is decent and I hate to give up on it just for this. I am sure somebody has an idea how to repair this. I have no way to broach (at least not yet) a square hole or a new "top" to the pinion could be made. I have attached a couple of photos for the knowledge base here to review. The journal area is .495 in dia and about .480 long. This is a 5" dia 3 jaw chuck. Any thoughts!

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[Kevinb71]

That might be a good idea! Would you use oil as a release agent? As in coat the chuck key with oil and press it into the puttyalready placed in the socket? Or would oil just squeeze off and stick the key?

 

[pineyfolks]

I cut the head off a socket head cap screw and brazed it in one of my old chucks, it's bin in there over 25yrs

 

[KenS]

I have no way to broach (at least not yet) a square hole or a new "top" to the pinion could be made. I have attached a couple of photos for the knowledge base here to review. The journal area is .495 in dia and about .480 long.

Since you have a lathe, you could bore the worn broached area of the pinion round. Then take a socket adapter-- or better yet, a square drive socket the size of your chuck key-- and turn it's perimeter to fit into the bore and part it off to the length of the new pinion bore. To complete the repair, silver solder the modified square drive into the bore.

The attached picture should help you visualize the repair.

 

[Syaminab]

If the original steel failed, I would hate the putty fails in the middle of a work, specially if I had finished the part. "Yes sr. Your part is finished, but we cant get it out the chuck"....just a joke. I would Tig weld and remachine with a 1/8 endmill, a 1/16 radius on the corners is fair enough, no need to broach to 0. Maybe file the sharp corners on the key just to fit if not enough.

So far, the best Idea to me is the silver solder the socket in place.

 

[Bobby Bailey]

I'd go with the modified socket or tig welding/milling. But , just for future info, Johnson's paste wax or Kiwi shoe polish are great release agents. A couple coats buffed out is what we use bedding rifles.
Bobby

 

[Kevinb71]

Thanks for the ideas guys! A couple of things to sock away for potential future issues. For now I think I'm going with the socket portion silver soldered in.

 

[Chrispy]

Here's another option;
http://sdp-si.com/web/html/newprdrsleeves1.

You can also make your own sleeves by milling to half depth in a piece of stock, cutting that stock in half , then weld or braze the two halfs together on top of each other with the "trough" in the middle. Turn to size in the lathe and voila you have a square hole without a broach.

 

[Kevinb71]

Chrispy
The link doesn't work for me, but i've got the idea. Thanks!

 

[george wilson]

Definitely try brazing in the new metal part. I am certain that JB weld would soon crumble(if not the first time). It's great stuff,but not for this application.