MadModder
Gallery, Projects and General => How do I?? => Topic started by: Kinkajou on April 28, 2011, 11:11:35 AM
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Hello forum members
I need some advise on my next project.
I bought some years ago a 4 independent jaw chuck with a 4” inch diameter, used a back plate to install it.
I guess it is a Chinese made chuck, not so bad in precision considering it would go to a Grizzly lathe that is also Chinese.
Looks something like this:
(http://www.mini-lathe.com/Mini_lathe/Chucks/4_jaw/3inch_4jaw_y.jpg)
Problem is that with time some parts started to get damaged because of a bad fit .
The screws started to stop moving, apparently something was stuck.
The screw I refer to looks like this:
(http://di103.shopping.com/images/di/45/77/65/3571314f7a73437242424a4d50724d356f4241-100x100-0-0.jpg)
The ones I have had a very bad finish specially on the center where the thrust bearing fits.
I later found that some thrust bearings were broken and that was the cause of a bad fit .
(http://www.toolguys.com/files/imagecache/cart/products/HK30890706.png)
It is difficult for me to get one of those chucks in Mexico, and I could try to import one but when I saw how the thrust bearings look it does not seem to be a difficult part to make.
But I do not have a clue on what material to use because it looks like the originals were made from a stiff material.
I thought on using maybe bronze or stainless steel but I read that there is a tool steel that can be machined easily and then temper it using high temperature. I think it is called O1. Or maybe some other metal?
What would you recommend for this task, or maybe you suggest to get another chuck and avoid all this?
In advance thanks for the advise.
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Hi Kinkajou,
My 4" 4 jaw must have come from the same batch, I just took mine apart, I used cold rolled and case hardened it, I haven't had any problems with it but I don't use it much either. Upon inspection you can see where it is wearing so it appears it should be made with a harder material. As you can see I drilled and tapped it, makes it a lot easier to remove. It wouldn't hurt to cut that slot centered either.
Hope this helps.
Edit- When I re-assembled the chuck the jaw screw retaining pin would only go in one way so I guess it isn't off center by accident/sloppy machining, it's been awhile since I made it, memory fades .
(http://img263.imageshack.us/img263/1103/parts028.jpg) (http://img263.imageshack.us/i/parts028.jpg/)
Uploaded with ImageShack.us (http://imageshack.us)
(http://img822.imageshack.us/img822/7140/parts030.jpg) (http://img822.imageshack.us/i/parts030.jpg/)
Uploaded with ImageShack.us (http://imageshack.us)
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Thank you, that is the part that I need to make, so maybe cold roll is a little to soft, right?
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Mine came out of the same batch I guess. The first time I snugged the chuck up one of my bearings sheared off both ears. I pulled the chuck apart and made 4 new ones out of 4140 steel on the spot. It took me about 2 hours to fab up the replacements and they have been going strong now for 2+ years. I blame myself partly because I tended to get heavy handed with my lathe when I first got it. I was employed as a machinist at the time and used to dealing with 10" and bigger chucks. I force myself to take it easy now.