Secret to centering a lathe chuck ?

Secret to centering a lathe chuck ?

Joined: April 25th, 2008, 12:25 am

March 22nd, 2012, 11:27 pm #1

Mine is very slightly off centre and thus out of allignment

I have 3 bolts on the back plate that fix it to the lathe and when they are loose they allow some movement to centre it and adjust -

but I can't seem to get it right -

I've tried putting a straight pipe in the chuck and pushing the up to it with a centering chuck on the other end -

everything looks aligned but when i power it up it still gives me a tiny wobble ....

never did before until I took of the chuck so that I had more room for a milling project ... my mistake ...

just need to get it back to the way it was ... any advice would be appreciated -

Cheers

James


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Joined: April 25th, 2008, 12:25 am

March 22nd, 2012, 11:36 pm #2







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Joined: January 1st, 2012, 11:50 pm

March 23rd, 2012, 1:23 am #3

Mine is very slightly off centre and thus out of allignment

I have 3 bolts on the back plate that fix it to the lathe and when they are loose they allow some movement to centre it and adjust -

but I can't seem to get it right -

I've tried putting a straight pipe in the chuck and pushing the up to it with a centering chuck on the other end -

everything looks aligned but when i power it up it still gives me a tiny wobble ....

never did before until I took of the chuck so that I had more room for a milling project ... my mistake ...

just need to get it back to the way it was ... any advice would be appreciated -

Cheers

James


Here is a way:

Put a piece of round stock in the chuck. Loosen the back plate just a little. If you have a dial indicator, indicate off the round stock. Rotate the chuck manually. With a rubber mallet, tap the chuck on the high side until it has the runout that you can live with. Tighten it firmly to the backing plate and recheck.

If you dont have a dial indicator, use a bit in the cross slide. Manually rotate and tap until there is even clearance between the bit and round stock.
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Joined: April 4th, 2005, 6:09 pm

March 23rd, 2012, 1:30 am #4






James,
the tailstock is almost never exactly on center. I suggest a dial indicator and the roundest piece you've got, perhaps a large endmill in the chuck. Forget the tailstock, chuck it up, put the dial indicator on it,and see where it is off and tap the chuck to center. Most 3-jaw will runout about .003. You may be able to get it closer, but repeatability will always be an issue, especially with a threaded chuck.

when I had a lathe with threaded spindle, I'd spin it on to hand tight, then back it off, spin it back on about three times to seat it. Clean (!) threads will help a bunch.

Always here to help.

Jim
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Joined: April 25th, 2008, 12:25 am

March 23rd, 2012, 1:39 am #5

Mine is very slightly off centre and thus out of allignment

I have 3 bolts on the back plate that fix it to the lathe and when they are loose they allow some movement to centre it and adjust -

but I can't seem to get it right -

I've tried putting a straight pipe in the chuck and pushing the up to it with a centering chuck on the other end -

everything looks aligned but when i power it up it still gives me a tiny wobble ....

never did before until I took of the chuck so that I had more room for a milling project ... my mistake ...

just need to get it back to the way it was ... any advice would be appreciated -

Cheers

James


nt
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Joined: October 21st, 2001, 3:36 am

March 23rd, 2012, 6:41 am #6

Mine is very slightly off centre and thus out of allignment

I have 3 bolts on the back plate that fix it to the lathe and when they are loose they allow some movement to centre it and adjust -

but I can't seem to get it right -

I've tried putting a straight pipe in the chuck and pushing the up to it with a centering chuck on the other end -

everything looks aligned but when i power it up it still gives me a tiny wobble ....

never did before until I took of the chuck so that I had more room for a milling project ... my mistake ...

just need to get it back to the way it was ... any advice would be appreciated -

Cheers

James


James I use this so much, tapping chucks, stock, vises, etc. into place, I don't put it away anymore.


P.S. also, as suggested, you just can't work without one of these, a dial indicator and the magnetic holder.
http://www.amazon.com/Grizzly-G9849-Mag ... pd_cp_hi_1
Last edited by bigbore on March 23rd, 2012, 6:51 am, edited 1 time in total.
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