# new Chuck



## purplehorn1977 (Oct 7, 2010)

Ok well where to start. I have a central machine 7x10 mini lathe. after adjusting the gibs and slides have almost no lash in them. well set up the dial indicator on the chuck and have .001 run out. Using a round piece of HSS in the chuck. so i remove the check and check the spindle. runs perfect no runout. Now i know i am wanting to get a new 4" 4 jar thats independent. but i would also like to be able to use the 3 jaw. Is there a way to remove this runout or am i just better off to get the new 4" and then a 3" 3 jar also. thanks for any help. I wont even get started on the tail stock. i think it was made with a 10 pound sledge hammer and grinder and the guy said yep good enough.


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## peatoluser (Oct 7, 2010)

Hi purplehorn,
1 thou (0.001) runout on a selfcentring 3 jaw isn't all that bad. Generaly they aren't designed to be much better than that. There are very accurate 3 jaw chucks available but you pay for that accuracy. You can true a 3 jaw with a tool post grinder (you clamp a thin washer at the back of the chuck, a bit like trueing soft jaws) but strictly speaking you only make it accurate for that diameter. to obtain better accuracy you traditionaly use a 4 jaw independent and clock it in or use collets.


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## cfellows (Oct 7, 2010)

A runout of .001" for a three jaw chuck is pretty darn good. Have a look at this thread, starting with reply #37. 

http://www.homemodelenginemachinist.com/index.php?topic=9016.0

You might need access to a larger lathe to make the modifications I made, although you might be able to do the mods on your smaller lathe once you get your 4 jaw chuck.

Chuck


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## Twmaster (Oct 7, 2010)

.001" runout is pretty good for that machine/chuck. I had one of those lathes previously. IIRC the chuck was spec'ed to be within .003" of runout.

I would not stress over it.


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