# Pm1127vf-lb New Chuck Or Back Plate



## lpeedin (Nov 17, 2015)

Hi guys.  As many of you know I am the proud owner for almost a year now of a PM1127VF-LB lathe (and recently a PM727 mill).  I don't really use my 3 jaw chuck and one of the reasons why is that the run-out isn't the greatest.  It varies with each mounting between .005-.010" run-out.  I made sure to reinstall it with the witness marks lined up as it came from the factory.  Since then I have rotated the chuck through a full rotation of mounting on the spindle as well as removed the back plate and re-mounted that to each different orientation.  The results have been essentially the same no matter the mounting position.  

With that said, I would like to try a new scroll type chuck or possibly to even try to make a new back plate.  The problem that I am running into is that this lathe doesn't have a standard type of spindle nose such as a D1-3, D1-4, etc.  Does anybody have an idea of what kind of new backplate I would need?  I see places that sell semi-machined back plates, but, I can't seem to figure out what I would need.  I assume I would need to drill and tap mounting bolts so that is not an issue.  

With that, has anybody ever purchased new jaws for their PM1127VF-LB factory chuck?  I don't have a set up to grind the jaws, so I had thought about buying new jaws if possible.  Also, maybe even one of those six-jaw chucks?   

Let me know if you have any information that may help. 

Thanks, 

Chad


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## Dan_S (Nov 17, 2015)

Based on this thread i found the 1127 looks to have what is commonly called a plain back mount. 
http://www.penturners.org/forum/f166/new-family-member-pm1127vf-lb-126455/index3.html

The issue with the plain back mount is that no standard exists, so you are going to have to machine a custom back-plate for any chuck you buy.

I just did this for a new chuck for my lathe, you can see the process i used in this video.


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## stupoty (Nov 17, 2015)

Hello,

Sounds like its the backplate to spindle nose as your thinking, you can check the chuck for repeatability by marking a dot with a felt tip on the chuck and a round bar (a dowel pin is a fairly good thing to use if you have a long one) mark the chuck and bar for where they are when you first put it in, then look at the runout with a dial indicator, mark the high and low points on the circle and write down the numbers.

Remove the dowel (round bar) from the chuck and losen the chuck a little more then put it back in the same spot so the felt tip marks are lines up.

Re do the high / low spot check and write down numbers again.

Do that a few times should give you a good indication of the ability of the chuck to repeat.

You can check the 3 jaw to spindle in a similar way (just more booring if you have to bolt it down) check the high / low of the chuck body and make a note then take it off and put it back on then re mesure.

This should help to tell if it's worth re making the backing plate or if the runout is from the chuck itself.

Stuart


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## higgite (Nov 17, 2015)

Chad,
Have you tried the procedure on page 20 of the owner's manual?
http://machinetoolonline.com/files/PM-1127VF-LB_Manual_2012.pdf
or
http://www.machinetoolonline.com/files/PM-1127VF-LB_Manual_2015.pdf

Dan, it's not a direct mount in the usual sense. It uses a twist lock mechanism.
Nice video by the way.

Tom


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## Dan_S (Nov 17, 2015)

higgite said:


> Dan, it's not a direct mount in the usual sense. It uses a twist lock mechanism.



any pictures or anything, I'd be interested to see how this works?


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## Dan_S (Nov 17, 2015)

Tom is this what you mean?

http://www.mini-lathe.com/reviews/Lathes/Sieg_C8/C8.htm#Spindle


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## TommyD (Nov 17, 2015)

Have you taken it all the way apart and cleaned the scroll and teeth on the jaws?

We have a chuck like that, one of those with the cam lock that locks on 3 pins on the back of the chuck, correct? I was told it was taken apart at least twice by someone I was told was competent and it still runs out about .005. I haven't taken a shot at it yet but if when I do and it still runs out I may try another set of jaws....or encourage them to purchase another one, maybe a buck. It's a chinese chuck, I have my bias on it's quality.


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## Dan_S (Nov 17, 2015)

for reference, this is what Bison (pretty decent chucks) considers acceptable run-out on 3 jaw chucks.


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## RJSakowski (Nov 17, 2015)

Before attempting to true the mounting plate as on page 20 in the manual, I would check the hub and face of the back plate for runout.  If there is no runout seen there, any attempt to improve chuck runout by refacing will be of no use. The runout then would originate within the chuck itself.

Bob


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## lpeedin (Nov 17, 2015)

Tom, 

There is no twist lock, it is a direct mount with three bolts.  I will give the whole thing a once over this weekend. I love improving things rather than buying new things.


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## higgite (Nov 18, 2015)

3dshooter80 said:


> Tom,
> 
> There is no twist lock, it is a direct mount with three bolts.  I will give the whole thing a once over this weekend. I love improving things rather than buying new things.



3d,
Wow! That's what I get for speaking out of school. When I was researching lathes last year before I bought my new one (I went a different route), I was led to believe it had the twist lock mount, mostly by the owner's manual I guess. Sorry for adding nothing to the conversation, except some confusion. Back to square one, I'd go with Bob's advice.

Dan,
Yes, that's what I meant, but I was obviously wrong. 

Tom


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## TommyD (Nov 18, 2015)

So it located on a hub? I'm having a hard time imagining how this thing aligns or is fixed to the spindle. Is there a pic on this rig, I don't think I have ever seen a chuck being described and would like to see one before I ass-u-me anything more.


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## Dan_S (Nov 18, 2015)

higgite said:


> Dan,
> Yes, that's what I meant, but I was obviously wrong.



No worries man, I learned something new. I had not heard of cam lock until you mentioned it.




TommyD said:


> So it located on a hub? I'm having a hard time imagining how this thing aligns or is fixed to the spindle. Is there a pic on this rig, I don't think I have ever seen a chuck being described and would like to see one before I ass-u-me anything more.


Yea, the chuck registers on a hub, and then is held to the spindle with bolts or studs.


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## TommyD (Nov 18, 2015)

The hub runs true to the spindle? The hub is only slightly smaller than the recess it fits into? RJS alluded to this previously.

If all this is good I'd suspect internals of the chuck, scroll or the jaws are probably funky. Does the out of round follow a certain jaw if you rotate the chuck on the hub? Kinda like stupoty says but keep the dowel clamped, mark the dowel with tragic marker and rotate the whole chuck 120 degrees and see if it follows the high spot marked on the dowel.


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## lpeedin (Nov 18, 2015)

Excellent advice Tommy. All things I will check this weekend.  I have gotten very used to using the 4-jaw and indicating everything in. But, there are times when a 3 jaw would be so much simpler and faster.


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## lpeedin (Nov 18, 2015)

I thought I would show a quick pic of my most recent mod... roller bearings on the steady rest.  I got the idea from a guy on here that goes by Fabrickator.  He posted this mod for his Grizzly G0602 10×22 lathe.  It was pretty simple, just mill some fingers, turn a couple of custom screws that are a slip fit for the bearing races, turn a couple spacers, and slap it all together.


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## TommyD (Nov 19, 2015)

Nice idea on the steady rest. I've gotten a few good ideas from here already.


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## gheumann (Nov 20, 2015)

For the record I own a PM1127. You didn't say how you were measuring. My chuck is quite accurate - however it is very easy to get different "answers" when unchucking/rechucking.  You really have to feel a piece of bar into the chuck. If you're just resting a bar in there, clamping down the chuck and then measuring the bar I would not be surprised with the results you're getting. If not, I agree with the suggestions above.


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## lpeedin (Nov 20, 2015)

I don't think I follow you when you say I have to "feel" a piece of stock when chucking it. Do you mean I need to wiggle it around while tightening the jaws?


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## gheumann (Nov 20, 2015)

Yes, absolutely. Longer/thinner pieces - spin it; larger/shorter pieces wiggle - tighten the jaws very slowly. It is VERY easy to chuck something out of true - and if you just put the piece in a loose chuck and tighten the jaws, it is virtually guaranteed.


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## wrmiller (Nov 20, 2015)

What Greg said...


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## TommyD (Nov 21, 2015)

I've been guilty of not making sure a round piece is chucked properly when working toofast and using the center of the three jaws....got some pretty decent wobble out of it


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## lpeedin (Nov 23, 2015)

As a practice, I learned early on that I need to wiggle the stock around to make sure it seats true to the jaws, so that is a non issue.  I took the chuck apart, removed the back plate, removed all of the internals, cleaned, and lubed it all.  I checked the run out of the spindle face and the OD of the hub register and all is well there.  I did take a light facing cut on the spindle when  I first got the lathe and all was still well there.  I then bolted up the back plate and noted that the ID of the back plate had approx. .0025" of runout, even when mounted on the spindle.  However, the outer register of the back plate was approx .001" runout.  I decided to trim it back and cut a new register. I did that and got he chuck to mount well.  Now when I chuck something up, I get a consistent .004" runout assuming I tighten it with one particular key hole.  With the two other key holes, I get betweeon .005-.006" runout.  For my work, when I need a 3-jaw, .004" will be just fine.


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