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PostPosted: Sun Mar 18, 2007 4:13 pm 
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Joined: Wed Oct 12, 2005 8:38 am
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Location: Connecticut
Well I trued up the jaws on the 3-jaw chuck that came withe South Bend I recently bought. The information I learned from Harold V the last time in this thread: http://www.chaski.org/homemachinist/vie ... jaw+chucks came in handy once again.
This time the results were even better, .001" TIR, hope I can keep it that way :D .
Ernie F.


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PostPosted: Mon Mar 19, 2007 11:10 am 
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Joined: Mon Jun 27, 2005 6:18 pm
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Location: Connecticut
Ernie,

What did you use for a grinder?

Can you post a picture?

Steve


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PostPosted: Mon Mar 19, 2007 2:39 pm 
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Location: Onalaska, WA USA
Metalman wrote:
.001" TIR, hope I can keep it that way :D .
Ernie F.


That's pretty impressive, Ernie. Have you checked the chuck over a range of sizes? You can usually expect the runout to vary as you do---so if yours doesn't, you have a scroll that is well centered and very round.

You deserve the credit, Ernie. You did the work. Sadly, others may not enjoy your level of achievement---in spite of having read the same information.

Harold


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PostPosted: Mon Mar 19, 2007 10:11 pm 
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Steve
I didn't take any photos but used the same air die grinder in a photo on the other thread, (use the link I posted). I stone is about 1" diameter, 60 grit if I remember. What I did different this time was to clamp the die grinder to the side of a 4 way tool post instead of the Rube Goldberg I used the last time. That was a shorter, more solid set up with less (no?)flex. I spent a lot of time matching the heights of the jaws on the deep end and a lot of time making sure the slug was square in the chuck prior to grinding. I also set up a stop to keep the grinder from crashing into the slug. Many light cut passes with the stone, and even lighter near the end until almost no sparks.

Harold_V wrote:
Have you checked the chuck over a range of sizes? You can usually expect the run out to vary as you do---so if yours doesn't, you have a scroll that is well centered and very round.

I ground the chuck with a slug approximately 1.5" and checked with a short length of round stock about the same size but turned round. There it is .001" run out. From there I went to some 5/8" cold rolled for a project and it was .002". All new metal stock is suspect to me, and sometimes I can visually see improvements by rotating and trying different positions in the chuck.
It's still a three jaw and I will treat it as such, too many reasons for them not be perfect (if there is such a thing) but somewhere under .003" is something i can work with. The old chuck was loping like a camshaft at around .010" TIR.
Regrinding sure beats a few hundred for a new chuck and all the work to set it up. I noticed new chucks are advertised with various degrees of run out, less run out = more $.
Ernie F.


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PostPosted: Tue Mar 20, 2007 7:13 am 
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Thanks, Ernie.

My 3-jaw has a problem with the front of the jaws visibly more worn than the rear, so regrinding is on my list of things to do.

Steve


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