I have a Cushman 3 jaw, 9 inch chuck, on my Sheldon lathe that the jaws are non-reversable . The only Numbers I see on it are 8B4903. How does one go about getting a set of jaws? The ones I have are such that when trying to turn close to the chuck one risks crashing into it with the post or the compound. Is it a better solution to just shop for another 3 jaw?
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Purchasing lathe chuck jaws for a Cushman chuck
- Thread starter todd281
- Start date
- Joined
- Jun 7, 2013
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- 10,085
Perhaps it is an extreme statement, but it almost seems like there were never two chucks alike made and the chances of finding jaws to fit your chuck are close to slim and none; best cure is to buy an new chuck that suits your expectations/needs, hopefully, not made of Chineseium.
- Joined
- Sep 25, 2014
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- 1,111
Make them. Harold hall presents a procedure for making them with conventional equipment. The scroll teeth in behind are really not very fussy - they simply need to be evenly spaced. I had a similar issue on an old mill table chuck (basically a foot mounted lathe chuck) - it had only the reverse side one piece jaws. It took some figuring, but I made two sets of jaws, and made them both 2 piece jaws. I have a CNC mill, so once I had the method figured out, there was no holding back. With using a CNC it is straightforward to call out a little piece of a face spiral - and shift it by P/3 for the next jaw, and the same again for the 3rd one.
- Joined
- Sep 25, 2014
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As Ben (above) pointed out - no two chucks seem to use jaws that are the same. The chuck I was working on is a 12"-3J, I found dimensions for several 12" - 3J chucks, all were quite a bit different than the one I was working on. Making jaws seemed very intimidatingly - until I tried it. It really wasn't difficult.
- Joined
- Apr 14, 2014
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- 3,140
I think you're taking the least frustrating course by purchasing a new chuck. I have an older Union chuck that is missing one set of jaws. The chuck itself is in like new condition, but was missing one set when i purchased it. I have looked for a replacement set for over 20 years with no tangible results. I have found a few sets that are close, but still no cigar. I still keep my eyes open when visiting used equipment dealers, but over the years I've searched through thousands of possibilities with no real success.
- Joined
- Feb 26, 2014
- Messages
- 254
Could you post a picture, I can't quite see how the tool post or compound would interfere with the jaws. How do you have them positioned?
Here is a picture , I have changed the tool post to a QCTP but it has the same problem. As you can see, the jaws, because they are set to clamp external on larger projects , they do not allow the toolpost to get next to the internal jaw feet. Thus the bit is can never get right next to the support of the jaws unless there is allot of overhang on the tool. If the jaws are extended beyond the outer radius of the chuck , then Its possible for them to contact the compound. [sorry about the blurry picture]
