# PM 12x36



## slingshot (May 1, 2013)

Hello folks, I have got my lathe setup I got the tail stock lined up also trued up my spindle and chuck back plate.I am having trouble with my face plate it's almost like the taper in the plate is two small because the back plate want seat to the spindle. I'm wondering what is the best way to spin the face plate so I can take a little taper out?



Thanks
J.B


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## Ray C (May 1, 2013)

Take a piece of round stock (a few inches long at least) weld a piece of flat stock with two holed drilled in both sides to one end of the round stock.  The fixture will look T-shaped.  True it up as best you can.  Mount the round stock in a good chuck then, use bolts to clamp the faceplate through the holes.

Let me know if you need a better description.

Ray





slingshot said:


> Hello folks, I have got my lathe setup I got the tail stock lined up also trued up my spindle and chuck back plate.I am having trouble with my face plate it's almost like the taper in the plate is two small because the back plate want seat to the spindle. I'm wondering what is the best way to spin the face plate so I can take a little taper out?
> 
> 
> 
> ...


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## slingshot (May 1, 2013)

Ray C said:


> Take a piece of round stock (a few inches long at least) weld a piece of flat stock with two holed drilled in both sides to one end of the round stock.  The fixture will look T-shaped.  True it up as best you can.  Mount the round stock in a good chuck then, use bolts to clamp the faceplate through the holes.
> 
> Let me know if you need a better description.
> 
> Ray



 Thanks Ray I don't know why I didn't think of that I guess I didn't think hard enough.


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## Tony Wells (May 1, 2013)

Before I cut anything, I'd sure look for other reasons that would prevent it from shouldering out. Burrs on threads, dirt, etc. Clean it absolutely clean. But once you get it to fit, however you do it, put a little oil on the threads. Then you should probably take a skim cut to true the face up. Check with indicator before just to make sure it's really needed, but I would expect it to show some runout since obviously there is some sort of fit problem.


Or is this not a threaded spindle? Other issues are in play if it isn't.


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## darkzero (May 2, 2013)

Tony, it's a D1-4 spindle.

J.B., if the taper on the faceplate truly is too small to fit the taper on the spindle, I would recommend contacting Matt about it first rather than trying to repair it yourself.


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## Tony Wells (May 2, 2013)

Thanks, Will. I did fail to research that before commenting. 

Yes, best to contact Matt. If the chuck fits, and if you also have a 4 jaw that fits, there likely is a problem with the faceplate. You might try removing the pins and cleaning it thoroughly and see if it fit any closer, but before modifying it, definitely check with Matt on his idea for a solution.


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## Ray C (May 2, 2013)

This is a very common problem with "generic" backplates and two of my 3 backplates suffered the same ailment.  I think some companies purposely cut the tapers undersized.  Tony's right though, please do check for all other issues.

FWIW:  I ordered a backplate from Enco and mounted a chuck for a friend and he had the same issue -the lathe was not a PM and was 15 years old.

Slingshot, if you decide to clean-up the taper, spend a lot of time centering the setup and DI off the inside of the taper at two different spots.  This way, you won't throw the geometry off.  -And I'd be willing to bet that Matt will replace it if it's really off the mark.

EDIT:  Oh, the prototype shop lathe at work has D1-5 spindle and it's pretty old.  One of the backplates had the same issue but the prior operators didn't know enough to fix it.  Anyhow, I figured this was a common problem with plates...


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## qualitymachinetools (May 3, 2013)

Yes check it for burrs or anything, how close does it get? 

 I can swap it out for you if thats easier, no problem. Or its easy enough to clean that up, either way, no problem, just let me know.

 Also make sure the camlock pins are not too long, I saw that once too where they were bottoming out.


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## Ray C (May 3, 2013)

Matt,

Something I've noticed with a LOT of backplates is the taper/hole is cut very small.  I measured the spindle and it's dimensions were absolutely dead-on according to spec.  I've had generic backplates from Enco, Shars (and two of the three backplates that came with my PM1236) that were way undersized.  If you removed the pins and just placed the plate against the spindle face, you could not get the faces to meet because the tapered hole was too small and impeded the nose-cone from fitting.


I've seen this on many backplates and on two different lathes other than mine.


Ray




qualitymachinetools said:


> Yes check it for burrs or anything, how close does it get?
> 
> I can swap it out for you if thats easier, no problem. Or its easy enough to clean that up, either way, no problem, just let me know.
> 
> Also make sure the camlock pins are not too long, I saw that once too where they were bottoming out.


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## slingshot (May 4, 2013)

Thanks Matt there are no burrs or anything. The tapper is to small as ray stated. I will take care of that in a day or so.no problamo. 



thanks
JB


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## slingshot (May 9, 2013)

Hello everyone,

Well I finally Had a chance to do some more  work,I got my taper cut out on my face plate trued and ready to go,I also have got my 4 jaw back plate trued up man it's heavy. hew:

I  am have a problem with my three jaw chuck I have trued the back  plate,when I put a DI on the spindle I have 0 run out both ways same  with my three jaw back plate 0 TRI.The problem comes when I bolt the 3  jaw to the back plate the body has 5 thousands run out.I put a 12 inch  test bar in the chuck leave .500 out and put my di on it and I have 12  thousands run out.

I put my three jaw in the 4 jaw chuck to check  the run out on the back of the chuck where it bolts to the back plate  and it's only 1 thousand off .So I'm not sure where the problem is.:thinking:  while the lathe is running you can clearly see the wobble in the body  but the back plate has no wobble. any info would be appreciated.

Thanks JB


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## Ray C (May 9, 2013)

With a 3 jaw, you can mount a good rod in it, loosen the backplate just enough to hold it in place then adjust the body until the rod is zeroed -then tighten the backplate.  Just another option.  Of course, you could zero the body but then, you'll need to grind the jaws.  Most of the time, the scrolls are not even and the jaws only center in a small range of the overall travel.  Pick your poison...  


Ray


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## slingshot (May 9, 2013)

Okay so basically, If I am reading this right I could loosing the back plate from the chuck and maybe put a shim between them and tighten it? Them I am guessing that this would make my jaws off or maybe not.


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## Ray C (May 9, 2013)

Woah, wait a minute...  Are you saying the face of the chuck has runout or the body?  If the face is off, something else is wrong.

... I'll be able to reply more tomorrow.


Ray




slingshot said:


> Okay so basically, If I am reading this right I could loosing the back plate from the chuck and maybe put a shim between them and tighten it? Them I am guessing that this would make my jaws off or maybe not.


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## slingshot (May 10, 2013)

No it is the body that is out. The body shows 5 thousands out of round, but my test bar is showing 12 thousands out you can clearly see the wobble. so it maybe that the jaws are off to? 

 I may be in the market for a new chuck very soon,not to say that this one can't be helped lol.


Thanks.


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## Ray C (May 10, 2013)

OK, we're on the same page...

You can, if you want, try the procedure I mentioned.  It should not be that far off.  Give this a try...

Put a decent shaft in the jaws, loosen the plate holding bolts just snug, put a DI on the shaft 1" from the jaws and tap the body into position such that the dial zeroes.  Snug-up the plate bolts.  Now put a DI on the body.  Let me know the results.  We'll go from there.


Ray



slingshot said:


> No it is the body that is out. The body shows 5 thousands out of round, but my test bar is showing 12 thousands out you can clearly see the wobble. so it maybe that the jaws are off to?
> 
> I may be in the market for a new chuck very soon,not to say that this one can't be helped lol.
> 
> ...


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## Ray C (May 10, 2013)

BTW:  Most jaws on "economy" chucks do not hold square.  If you follow the procedure below, after you measure the RO on the body, the next thing I'm going to ask you is to measure the RO on the shaft about 3" further down from where you first took a measurement.  You will most certainly see a difference of a 3-5 thou.  If it's off way more than that, then it's time to true-up the jaws.  Under the best of circumstances 3-5 thou off is normal because there's no way in heck the jaws will settle into place repeatably.

BTW: when you're tightening a shaft in the jaws, it's a good practice to wiggle the piece with your fingers to help it settle into a normal and flat position in the jaws.  That's common practice and good habit as it can help the piece not get chewed-up by the jaws.


Ray


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## slingshot (May 10, 2013)

Okay,I did not know there was that much adjustment in the screws on the back of the face plate.Okay so here it goes,I adjusted until I got with in 4 thousands on the test bar at the jaws ( man I sure was hoping to ge it down to at least 2 thousands )I moved the di out ummm 3 three inches and I have 11 thousands run out, so the jaws must be out. I need my sponge filled with info. :whistle:


Thanks




Ray C said:


> BTW:  Most jaws on "economy" chucks do not hold square.  If you follow the procedure below, after you measure the RO on the body, the next thing I'm going to ask you is to measure the RO on the shaft about 3" further down from where you first took a measurement.  You will most certainly see a difference of a 3-5 thou.  If it's off way more than that, then it's time to true-up the jaws.  Under the best of circumstances 3-5 thou off is normal because there's no way in heck the jaws will settle into place repeatably.
> 
> BTW: when you're tightening a shaft in the jaws, it's a good practice to wiggle the piece with your fingers to help it settle into a normal and flat position in the jaws.  That's common practice and good habit as it can help the piece not get chewed-up by the jaws.
> 
> ...


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## slingshot (May 10, 2013)

Tanks Ray for your help. so where is all the others on this forum? Anyway @three inches out I can get it to 0 ro with the screws lightly snugged but when I start to tightening it don't matter which one or how much pressure it draws it back to where I started,

Looks like the 4 jaw is going to go back on.


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## slingshot (May 10, 2013)

I am really starting to think that the chuck back that mates to the plate really,IS not true to the body & jaws.


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## slingshot (May 10, 2013)

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.





slingshot said:


> I am really starting to think that the chuck back that mates to the plate really,IS not true to the body & jaws.


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## qualitymachinetools (May 10, 2013)

Hey you beat me to it, thanks for the help Ray! So are you all set to go now? Just want to make sure!


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## Tony Wells (May 10, 2013)

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.


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## Ray C (May 10, 2013)

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


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## slingshot (May 10, 2013)

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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## Ray C (May 10, 2013)

No, thankfully it doesn't seem to end -and that's the beauty of it.



slingshot said:


> 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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