# 4 jaw chuck mounting



## Nigel123 (Aug 10, 2020)

After owning the lathe almost 20 years discovered the 8 inch 4 jaw chuck is only bolted on (no recess machined)
In my defense I seldom use it took it apart to clean it for the first time (I think getting old)
I set it up to machine it, the run out is about 0.0005 thou but I noticed the countersunk cap screws are set deep
there is only about 3/8 inch of meat left so if I machine 3/16 off its getting a little thin
I have come up with some options
Leave as is 
Bolt and pin a spacer and machine it to fit the recess in the chuck
Hope I explained this okay
what are your thoughts


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## markba633csi (Aug 10, 2020)

There's nothing really wrong with having no recess on a chuck mounting, especially with a 4-jaw
Why make more work for yourself?
As long as the bolts are tight you should be fine;  5 thou runout is not bad- or did you mean 5 tenths?
-Mark


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## Bob Korves (Aug 10, 2020)

.0005" runout is about as good as you will ever get it, and the 4 jaw does not care so much about running true.  I would make sure the fasteners are holding the chuck tight to the spindle, and then leave it alone.  I understand you have only used the 4 jaw for the last 20 years???  Well then, maybe you are also good for the next 20...


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## Nogoingback (Aug 10, 2020)

markba633csi said:


> There's nothing really wrong with having no recess on a chuck mounting, especially with a 4-jaw
> Why make more work for yourself?
> As long as the bolts are tight you should be fine;  5 thou runout is not bad
> -Mark




5 tenths, not 5 thou'.  Even better...


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## Nigel123 (Aug 10, 2020)

Nogoingback said:


> 5 tenths, not 5 thou'.  Even better...





Bob Korves said:


> .0005" runout is about as good as you will ever get it, and the 4 jaw does not care so much about running true.  I would make sure the fasteners are holding the chuck tight to the spindle, and then leave it alone.  I understand you have only used the 4 jaw for the last 20 years???  Well then, maybe you are also good for the next 20...


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## Nigel123 (Aug 10, 2020)

Thanks for the replies advice
Not sure if it was acceptable to run this way and have avoided machining cast
Had it setup to do when I noticed the thickness and decided to post for answers
Very happy I did and grateful for the advice
My day is suddenly a lot brighter thanks Nigel


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