PM 12x36

Well I'm not always right but in this case I was,The back of the chuck was not true put it in the 4 jaw cleaned it up.I got it about .0015 @ 4 inches out so for a three jaw hmmm dang it boy that's pretty dang good. Thanks for your tips ray.



I am really starting to think that the chuck back that mates to the plate really,IS not true to the body & jaws.
 
Hey you beat me to it, thanks for the help Ray! So are you all set to go now? Just want to make sure!
 
If you have a known accurate, straight bar that will fit thru the chuck, and has a good center hole in it, you can chuck the bar about halfway in the three jaw, on the bench. Then put the bar in the 4 jaw and use a good center. Indicate it in dead on with the 4 jaw and you can skim the chuck od and back to get it true to that known good bar. That has solved many a problem chuck for me. If that makes any sense the way I described it.
 
Some folks have a tendency to cut a shoulder on the back plate that "precisely" fits the recess in the back of the chuck. Other than to complicate matters, I've never seen a good reason for doing that. Yes, I put a shoulder on the plate but, it's not so tight that you can't wiggle the chuck around a little. Once the chuck is positioned and the bolt tightened, it ain't going anywhere.

My procedure is like I mentioned below. Put a good shaft in the chuck and put a DI 1" from the jaws. Center the body on the plate until the RO is 0. Snug the bolts. Tightening them should not throw off the reading too much -if any at all. DI 3-4" further down the shaft. If the RO is within 3-5 thou, call it day. If the RO is more than that, you should probably grind and even-out the jaws. You can go through all this then, try a different diameter shaft -and chances are, it won't center as well as the 1st shaft did -and that's because of 2 things. A) The jaws float and never really lock-up exactly the same way. B) The scroll is probably not dead-on. If you get a $700 chuck, things should improve a little but, it's always a matter of time before something starts to wear out and things will get sloppy.

I happen to really like the chucks that came with my 1236. The 6" is nice and tight and holds well, so does the 8" and both only needed minor balancing. I need to fine-tune the 6" a little bit more but, I'm not losing sleep over it.


Ray
 
To be honest Ray I like the four Jaw that came with the Pm and the 6'' 3 jaw seems to be good also it just needed a little TLC. I've got to get a collect chuck and some collects I'm thinking about the er collects.I don;t think it ever ends lol.
 
No, thankfully it doesn't seem to end -and that's the beauty of it.

To be honest Ray I like the four Jaw that came with the Pm and the 6'' 3 jaw seems to be good also it just needed a little TLC. I've got to get a collect chuck and some collects I'm thinking about the er collects.I don;t think it ever ends lol.
 
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