# PM727M DILEMMA



## Brad125 (Sep 23, 2020)

Ok, so from the tech guy over at PM, i used a precision square to shim the column straight, as much as i can anyway. Its within .001 vertically over 7" in both the X and Y axis. 
	

		
			
		

		
	









	

		
			
		

		
	
Here comes the part thats really eating at me. After all the careful shimmimg it took.025 in the X-axis and .005 in the Y-axis. So then i indicated my head into my table to .0005 over 14" using a precision ground 123 block. Sounds like everything should be square right? Wrong! I raise the head up 3" and tighten the Z-axis clamps take a reading and sure enough i still measure .0075 off. So, i raise the head to 6" from the surface of the table and once again tighten the Z-axis clamps. Took a measurement and now its .015 thousands off!!! I did exactly the procedure that the tech guy told me. Yet i still have the same results as before. Below are the pics i took quick before calling it a night. What should i do about this????? Yes i know my indicator isnt a browne & sharpe, but since i dropped it while trying to get this machine fixed its all i can afford for the time being, plus i got the same exact readings with my browne & sharpe so i know its atleast accurate.


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## Brad125 (Sep 23, 2020)

And i didnt use the head to square up the column, i used a magnetic indicator holder and attached it straight to the dove tail piece behind the head.


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## davidpbest (Sep 23, 2020)

I can't tell from your description of how you're going about this, but from the amount of error you're seeing, I recommend you do some gross checks first to determine the behavior moving the head, and secondarily the quill up and down.   Here's a link to a video showing a process worth considering for the gross alignment.


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## shooter123456 (Sep 23, 2020)

I am having a hard time picturing what exactly you are measuring.

When you say you squared the column using a precision square, you mean you placed the square on the table, then an indicator attached to the dovetail slide indicating against the square, then moved the slide up and down, then placed shims between the column and the base until the indicator movement was minimized.  Is this correct?

When you say you indicated the head to .0005" over 14" using a precision 1-2-3 block, you are referring to the head tram with something placed in the spindle to hold an indicator, then rotating the indicator to the left and right to measure against a 1-2-3 block, then wack the head with a hammer to get the tram error minimized.  Is this also correct?

Then you move the head up and take another measurement.  What are you measuring here that is giving you .0075" deviation then again with .015" deviation?


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## markba633csi (Sep 23, 2020)

I'm also a little confused as to how you are measuring the Y error
-Mark


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## Brad125 (Sep 23, 2020)

shooter123456 said:


> I am having a hard time picturing what exactly you are measuring.
> 
> When you say you squared the column using a precision square, you mean you placed the square on the table, then an indicator attached to the dovetail slide indicating against the square, then moved the slide up and down, then placed shims between the column and the base until the indicator movement was minimized.  Is this correct?
> 
> ...



Yes, exactly.


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## shooter123456 (Sep 23, 2020)

Brad125 said:


> Yes, exactly.


I think you missed the question:  Then you move the head up and take another measurement.  What are you measuring here that is giving you .0075" deviation then again with .015" deviation?


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## Brad125 (Sep 23, 2020)

shooter123456 said:


> I think you missed the question:  Then you move the head up and take another measurement.  What are you measuring here that is giving you .0075" deviation then again with .015" deviation?



That is the measurement taken 3" above the table on top of the 123 block, and another at 6" above the table taken from 2, 123 blocks stacked together. This measurement is taken after i have already trammed the head to the table to be darn near perfect.


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## addertooth (Sep 23, 2020)

If your measurements are accurate, you are certain to vehemently dislike the answer.
or,
The gib in your column is mal-adjusted and has slop.


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## Brad125 (Sep 23, 2020)

Yes, my measurements are correct or very very close. I have been working on this for weeks now. Both matt and the tech guy said they thought the gib could be bad, and that if they sent me a new one that i would have to "fit" it to my machine.


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## Brad125 (Sep 23, 2020)

I have already adjusted the gib, i cant go any tighter as it already binds on the dovetails on both the bottom and top of the column.


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## addertooth (Sep 23, 2020)

What you are relating is a very bad sign.  If your gib is not seriously mis-manufactured, then the problem is with the column itself.


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## Brad125 (Sep 23, 2020)

I don't know, i just got off the phone with PM again, and there wasnt anyone from tech there to talk to and mike was out. I told them i did everything they suggested and its not working. The guy on the phone was very understanding but said they are backed up there. I just have been working on it for weeks and am about to call it quits. Starting to regret my decision buying this machine.


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## addertooth (Sep 23, 2020)

You are almost at the finish line. I would say give the new gib a shot.  If you can't resolve it with a gib-swap/tweak... then you are in a good position to ask for a replacement. Even reputable shops can get a unit which did not match the specs they specified with the manufacturer.


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## Brad125 (Sep 23, 2020)

I hope something can be figured out, im just so frustrated with the whole sisuation.


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## Janderso (Sep 23, 2020)

Brad,
be thankful you chose to purchase this machine from a reputable reseller.
PM will do their best to satisfy you.


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## Brad125 (Sep 23, 2020)

Yes i am glade i did, i have bough a few other tools from them with no issues. The situation is compounded because i am in gunsmithing school and have my final project coming up in 2 weeks, that includes machining a 80% lower for an Ar10. And i am stuck because who knows how that will turn out if i cant get this fixed by then. I have already been working with PM for a quite awhile on the issue and getting nowhere. I do have faith they will make it right, its just im pressed for time. I just sent them another email including the pics as directed by the fellow on the phone. I hope they get it soon as they havent responded to my last email i sent on the 17th.


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## shooter123456 (Sep 23, 2020)

Brad125 said:


> Yes i am glade i did, i have bough a few other tools from them with no issues. The situation is compounded because i am in gunsmithing school and have my final project coming up in 2 weeks, that includes machining a 80% lower for an Ar10. And i am stuck because who knows how that will turn out if i cant get this fixed by then. I have already been working with PM for a quite awhile on the issue and getting nowhere. I do have faith they will make it right, its just im pressed for time. I just sent them another email including the pics as directed by the fellow on the phone. I hope they get it soon as they havent responded to my last email i sent on the 17th.


The machine would need to be seriously messed up to be unable to complete an 80% lower acceptably.  I have made one using a $60 harbor freight drill press and a dremel.


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## JRaut (Sep 23, 2020)

Sounds to me like maybe your column is not straight. Is there any way you could get in there with your 1/2 thou DTI mounted to a height gage set on the table?

Then measure the distance to the column over the full height of your height gage.

1) If it's 0 all the way up, I don't know what the problem is. EDIT: <--- It's probably the gib, I suppose. Don't know what else it'd be here.

2) If it's _linearly_ varying with height, your column is straight but not plumb to the table.

3) If it varies _nonlinearly_ with height, you've got a column that isn't straight.

I hope it's not option 3, but that's what it's sounding like to me.


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## davidpbest (Sep 23, 2020)

I agree with JRaut.  Check the head position variation relative to a precision square on the XY table as illustrated in the video I linked to above.  Assuming the gib is finely fit to the machine and properly tightened, that method will tell you if you have a straight column: linear variation and it’s a tram issue, non-linear variation and the column isn’t straight. Check the quill movement is coplanar to the head movement using the same method.


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## Brad125 (Sep 23, 2020)

I should be able to, problem is i dont have a height guage, if its like the ones i use to use.


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## Brad125 (Sep 23, 2020)

When i attached my square to the table and lower the quill, there was .005 of devation over 3". I havent checked this since re-shimming the mill.


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## davidpbest (Sep 23, 2020)

Brad125 said:


> I should be able to, problem is i dont have a height guage, if its like the ones i use to use.


You shouldn't need a height gauge - just a precision square and the ability to mount an indicator on the head or in the spindle.  Did you watch the video?


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## Brad125 (Sep 23, 2020)

davidpbest said:


> You shouldn't need a height gauge - just a precision square and the ability to mount an indicator on the head or in the spindle.  Did you watch the video?



Yes, i squared my column to the table using a precision square laid on the table and a magnetic base indicator holder mounted to the dovetail slide directly behind the head, shimmed the column square to the table. Then trammed the head to "0" with the table. The problem comes when i raise the head, everything should be "in-line" but its not. The higher i go the more the head leans to the right, even with the colums squared, and the head trammed to the table. The devation seems to increase equally as the head goes up. Example: my head lowered to the table and trammed "0", then head is lifted 3" and the error is .0075, finally the head is raised to 6" and the error increases to .0155.


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## davidpbest (Sep 23, 2020)

Brad125 said:


> When i attached my square to the table and lower the quill, there was .005 of devation over 3". I havent checked this since re-shimming the mill.


If the column isn't trammed properly, or is not straight, or there is slop at the gib, your quill check is meaningless.   Get the column in tram first by checking the head movement against the precision square secured to the XY table.  If every 2" of head travel yields the same variation reading on the indicator, chances are good the column is straight but out of tram.   If the measurements differ more than a few tenths for every 2" of head travel, then the column probably isn't straight or there is looseness in the head-to-column connection (probably the gib).   Once the column is proven to be 90-degrees to the XY table, you can check the quill to see if it precisely follows the column axis using the same method.  If it does not, then the head-to-column mount needs to be adjusted/shimmed.


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## Brad125 (Sep 23, 2020)

davidpbest said:


> If the column isn't trammed properly, or is not straight, or there is slop at the gib, your quill check is meaningless.   Get the column in tram first by checking the head movement against the precision square secured to the XY table.  If every 2" of head travel yields the same variation reading on the indicator, chances are good the column is straight but out of tram.   If the measurements differ more than a few tenths for every 2" of head travel, then the column probably isn't straight or there is looseness in the head-to-column connection (probably the gib).   Once the column is proven to be 90-degrees to the XY table, you can check the quill to see if it precisely follows the column axis using the same method.  If it does not, then the head-to-column mount needs to be adjusted/shimmed.




Thanks for the tips, see my above post. I responded same time as you. Just incase you missed it


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## davidpbest (Sep 23, 2020)

Brad125 said:


> Yes, i squared my column to the table using a precision square laid on the table and a magnetic base indicator holder mounted to the dovetail slide directly behind the head.


This is not good technique for precision measurement. Your reference should be from an indicator in the spindle to a precision square on the surface of a locked-in-position XY table.


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## Brad125 (Sep 23, 2020)

davidpbest said:


> This is not good technique for precision measurement. Your reference should be from an indicator in the spindle to a precision square on the surface of a locked-in-position XY table.



I tried that way before, i dont remember the results. I should have documented it. However, the tech guy at PM said that was the wrong way to do it. He said the square the column with the table 1st, then tram the head to the table.


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## davidpbest (Sep 23, 2020)

OK.   Good luck.


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## Brad125 (Sep 23, 2020)

davidpbest said:


> OK.   Good luck.



Do you reccomend a different way that has worked for you? I will try about anything at this point.


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## mattthemuppet2 (Sep 23, 2020)

it doesn't matter if the column itself is square, you need the dovetails the head rides on to be square with the table. That's why you have to check the head by measuring with a DI/ DTI on the head (or in the spindle) against a standard on the table while raising and lowering the head.


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## davidpbest (Sep 23, 2020)

Yes.   See my previous posts.  mattthemuppet2 is precisely correct in his statement.   I use a large cylinder square because it's easy to indicate to from any direction and is heavy enough to sit flat on the table and stay put.  But lightly clamping a precision square to the XY table works also.   





​


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## mattthemuppet2 (Sep 23, 2020)

that's a good excuse to buy more metrology equipment


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## Brad125 (Sep 23, 2020)

mattthemuppet2 said:


> it doesn't matter if the column itself is square, you need the dovetails the head rides on to be square with the table. That's why you have to check the head by measuring with a DI/ DTI on the head (or in the spindle) against a standard on the table while raising and lowering the head.



I been mounting my DTI on a magnetic base mounted to the head plate that rides ontop of the dovetails. Then squared the colums using the ways with the DTI riding up and down a precision square placed to stand vertically on the table to get the X-axis squared.


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## Brad125 (Sep 23, 2020)

Yea i cant afford one of thoes or i would already have one.


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## GunsOfNavarone (Sep 23, 2020)

Man...I don't know. I understand being busy, but 1st come 1st served. If you bought that machine 2 months ago, your pretty much 1st in line. If there are customers _prior _to 2 months ago that take precedense...there's a big problem. I'm not knocking PM, the forums speak highly of them, that's good enough for me, but I also feel for the person that dropped $xxxx and has been very patient. You both can't be right. Since I have the same machine, if I can give you any measurements/readings (?) I'm happy to help.


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## shooter123456 (Sep 23, 2020)

GunsOfNavarone said:


> Man...I don't know. I understand being busy, but 1st come 1st served. If you bought that machine 2 months ago, your pretty much 1st in line. If there are customers _prior _to 2 months ago that take precedense...there's a big problem.


Could be a communication thing.  They have had a few issues with emails recently where the emails either don't make it to them or their replies don't make it back.  It has been very rare that I don't get a response from them the same day I contact them, and the one time it took longer, it was because my email did not make it.  But it does sound like they are in touch, just having a bit of difficulty isolating the issue.


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## Brad125 (Sep 23, 2020)

Yea, i was hoping they wernt blowing me off because maybe they didnt have an answer for me or a solution for the problem. I mean if i was wrong i wouldnt be wasting their time. I have a busy life that i cant hardly keep up with, so i have better things to be doing that trying to fix this thing. I like PM's products and will continue to buy from them in the future. I plan on buying a bigger mill from them when i have the space. I just think i got a dud and thats all there really is to say, especially after as much time as i have into it. I have done everything PM asked of me and more. I hope they have a solution, i am located 45 mins away from their shop. Id pack it up and take it there for them to look at, if i didnt have to completely tear it back apart to get it out of my basement by myself. That really sucked...


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## Brad125 (Sep 23, 2020)

Is there any way to square up the spindle 1st, then be able to raise the head and by measuring the deviation, shim the base? Kinda working backwards but if my spindle isnt perfectly square, maybe its adding additional error???


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## addertooth (Sep 23, 2020)

Brad125,
Do you have a lathe as well?  If so, you can make that 3 inch cylinder.  The key things is to know what your taper is... and you can measure that with a micrometer and have it as a known adjustment.


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## Brad125 (Sep 23, 2020)

Yes i do have a lathe also, however, it is apart for repairs. I tried using a piece of drill rod in the spindle about 8" long maybe. Then used a dti to try and center the rod at both ends, then shim the colums for the difference. But my drill rod didnt seem to be straight enough.


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## mattthemuppet2 (Sep 23, 2020)

with issues like this it's worth making a plan and writing everything down.

Square column to table in X and Y. Use a precision square clamped upright to your table. The longer the better - those 123 blocks might not give you enough length to get the column really square. You can always check the column higher up by clamping (some how) the square on top of a 123 block. Make sure you lock the column gib before making a measurement.

Tram head to table, ideally by sweeping directly off the table itself. Make sure your DI/ DTI is repeatable as you'll be going over the table slots. Lock all gibs.

Check quill to table, using the precision square clamped to your table. Lock all gibs and lock quill at top and bottom when you make your measurements.

You can also take unlocked/ locked readings - that will tell you something about your column gibs. You'll get some movement on the DI/ DTI, but it shouldn't be much.

Then report back. Otherwise you'll be chasing your tail and it'll be hard for us to figure out what you've done and what it means.


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## Brad125 (Sep 23, 2020)

mattthemuppet2 said:


> with issues like this it's worth making a plan and writing everything down.
> 
> Square column to table in X and Y. Use a precision square clamped upright to your table. The longer the better - those 123 blocks might not give you enough length to get the column really square. You can always check the column higher up by clamping (some how) the square on top of a 123 block. Make sure you lock the column gib before making a measurement.
> 
> ...



I have done everything you stated already except for checking the quill since re-shimming. When i lock and unlock the the Dti will move about .025, the bottom clamp always moves the DTI alot when unclamped. Also the gib is adjusted properly. In my earlier post, you will see i use a 8" precision square to square the column. I only use the 123 block to get height off the table. Still when the gib is locked down it should be "0".


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## mattthemuppet2 (Sep 23, 2020)

awesome, can you right all that down in one post? Makes it easier to refer back to.

I'm no expert, but 0.025" movement between locked and unlocked head/ column gib seems to be alot. Yet I think I read that you had it adjusted to the point that it was binding. Have you taken the gib out to check for straightness and twist?


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## davidpbest (Sep 23, 2020)

Based on your most recent information, the head-to-column interface at the dovetail ways is sloppy and needs to be corrected before any of the other tests and tramming processes are appropriate.  Sounds like some combination of gib fit, rough or wavy way surfaces on either the head mounting or the column, or both.    

On my Rong Fu 45 (Taiwan manufacture), with a properly fitted and adjusted gib, the head would sag no more than 0.003” when the locking levers were loosened (often less), yet the head would move up/down (with levers unlocked) without excessive force. Loosening the gib would not significantly ease the force required to raise/lower the head, but did induce more head sag, but did not alter the tilt or lateral position.  Granted, I hand fitted the gib to the dovetails using Prussian Blue marking and Swiss files/lapping with 500 grit paper on glass.  But even before that fitting, the sag was no where near what you are experiencing (0.008” as I recall).

I recommend you get a replacement gib, then re-test and be prepared to tweak the gib fit (common need with entry level Chinese equipment), or exchange the mill for a replacement. A badly fitting gib can be the source of the head wallowing around under pressure or relocation on the column even when it’s clamped down to a point the head won’t move.


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## Brad125 (Sep 24, 2020)

Pm272m video.   Here is a video, tell me what you think?


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## davidpbest (Sep 24, 2020)

I watched your video and I stand by my last post.


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## Brad125 (Sep 24, 2020)

Thanks for watching it, its pretty bad aint it?


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## Brad125 (Sep 24, 2020)

I sent the video to PM aswell.


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## shooter123456 (Sep 24, 2020)

Brad125 said:


> Also the gib is adjusted properly.


Are you positive about this?  On my machine, the gib doesn't always sit quite right when being inserted and adjusted.  The screws can sort of push it off to one direction so that it will bind long before it is in correctly.  

If it isn't sitting quite right, it could be tightened until the axis is binding, then back off a little, and it won't be even close.  Then when you tighten the locks, you are actually bending the gib to force the dovetails into the right position which is causing the head to move.


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## Brad125 (Sep 24, 2020)

I took the pressure off the head, completely loosened the lower gib screw and then tightened the top gib screw until it the screw got tight then backed it off half a turn. It binds on both the upper part and lower part of the column.  So, i am loosing a few inches on travel already at both the top and bottom. How can i tell for sure?


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## mattthemuppet2 (Sep 24, 2020)

sounds like a Friday afternoon special. I would negotiate with PM about returning it for a replacement. Binding at either extreme of travel usually indicates noticeable wear in the middle, which can't be the case here as it's new. You're starting to get into the realm of accurately mapping out the column dovetail and that's really more work than you should be doing for a machine under warranty.


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## Brad125 (Sep 24, 2020)

mattthemuppet2 said:


> sounds like a Friday afternoon special. I would negotiate with PM about returning it for a replacement. Binding at either extreme of travel usually indicates noticeable wear in the middle, which can't be the case here as it's new. You're starting to get into the realm of accurately mapping out the column dovetail and that's really more work than you should be doing for a machine under warranty.


Mattthemuppet2, did you see the video?


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## mattthemuppet2 (Sep 24, 2020)

yes, that's an awful lot of movement. As David wrote, a few thou is normal (my knee is ~0.002", my quill is ~0.001), but 30 thou is way off. Without any other information I would said "that's a crazy loose gib", but you've already said the gib is tight.

Only other suggestion is to repeat the test with the gib tightened as you wrote in post #51 at the top, middle and bottom of the travel. If the head is binding at either extreme, then you should see a much smaller distance between locked and unlocked at the ends compared with the middle. If that turns out to be the case, then your column dovetails are not parallel but "wasted" in the middle.

Another quick Q - do the dovetails have way oil (or some kind of oil) on them? Just another thing to check.


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## Brad125 (Sep 24, 2020)

mattthemuppet2 said:


> yes, that's an awful lot of movement. As David wrote, a few thou is normal (my knee is ~0.002", my quill is ~0.001), but 30 thou is way off. Without any other information I would said "that's a crazy loose gib", but you've already said the gib is tight.
> 
> Only other suggestion is to repeat the test with the gib tightened as you wrote in post #51 at the top, middle and bottom of the travel. If the head is binding at either extreme, then you should see a much smaller distance between locked and unlocked at the ends compared with the middle. If that turns out to be the case, then your column dovetails are not parallel but "wasted" in the middle.
> 
> Another quick Q - do the dovetails have way oil (or some kind of oil) on them? Just another thing to check.



Yes i use sae 30, cause its the only thing i can find locally. It is alway very well lubed and well taken care of. I am always wiping it down and cleaning it.


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## GunsOfNavarone (Sep 24, 2020)

I posted my reply here I got from PM for the same exact situation (as your video). Ultimately they say no matter if you cutting or calibrating, it will be locked, so the movement is of no matter. You tighten on gob lock and it goes one way, tighten the other and it comes back around, once you tighten both they don't equal zero, but where ever they end up, your going to calibrate that compensation in. This is what I was told. I will also say, I gave my Z gibs adjusted to where I am happy with them. I truly believe you will get no fix for this from PM, at least I don't know why you would get a different answer than I received.


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## mattthemuppet2 (Sep 24, 2020)

that's pretty shonky. So do you have a specific gib tightening order, as the OP showed a variation in movement depending on which gib was locked? I'd want to be really sure that whenever I reposition the head I can get it to lock up in exactly the same position relative to the table.

And that doesn't deal with the OP's issue of the head binding at the top and bottom of the travel when the gib is tightened properly.

Hopefully PM will sort this out, otherwise I struggle to see how anyone could recommend this mill.


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## Brad125 (Sep 24, 2020)

Exactly, dont forget the colums needs 0.025 thousandths of shims to be square. I mean, dont get me wrong, i am not expecting super high precision, but when you can not even move the head up and atleast maintain reasonable positioning the something is wrong, especially when it is out this far. I am not bashing PM as i have stated before, i like there products and quality. I honestly believe I recieved on that was out of spec. I read somewhere else that Matt checks one every so often, so, atleast he tries to assure his standards are met. This one just slipped thru the cracks. It happens, its todays manufacturing techniques. However, i am sure if Matt seen this himself, he would agree that something is wrong and would make the situation right. I mean these machines cost alot of money, atleast to me they do. So, when i invest that much money into a machine i want to know its right, or atleast know i will be taken care of. Thats why I bought from PM cause of there reputation for both customer servise and support.


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## GunsOfNavarone (Sep 24, 2020)

Well, I hope it's not stalling until a certain amount of time passes. You live close? I understand moving from basement is not easy, perhaps remove column, take it in and have them exchange it. Is that the problem? With the tight then loose gibs and the inconsistency depending where the head is located vertically...maybe. I don't know what the best versus easiest answer is, but I'm watching this thread for sure.


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## Brad125 (Sep 24, 2020)

I live within an hour of there company.


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## jaek (Sep 24, 2020)

How tight was your Z-axis gib in that video? When you tighten the handles, how far do you have to turn them from the first point of resistance until they are snug enough that it's hard to move the head?

Just checked the PM-727V in my garage - if I rotate the handle so that it flops down to 3:00 when looking at it from the left side of the mill, I can turn it to about 5:00 before it gets pretty snug. If you can tighten yours much further than that your gib is too loose...


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## tweinke (Sep 24, 2020)

I also have a 727m that is well out of warranty. Now that you mention your issue I have a thought. I just went out to the shop and tried mine. the head does move similar to yours when tightening the locks. And also I know for a fact if I adjust the gib at the center of travel on the column it does bind at the top and bottom. I have noticed this since the machine was new. I remember measuring the column dovetail with pins at the top and bottom and that the center area measured narrower but don't remember the numbers.  when my mill arrived the Z axis locks were very tight and the quill was setting on a wood block on the table. Now that you bring up your issue I wonder if the column was distorted by the locks being so tight during shipping. This is probably an issue I should have addressed under warranty. My theory is that the dovetails are closer together in the middle then at the top or bottom.


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## Brad125 (Sep 24, 2020)

Thats how mine is, loose in the middle and really tight on top and bottom. The z-axis gibs are tight enough that the the travel of the head will stop 3" before the top of the head abd about 2 inches on the bottom


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## tweinke (Sep 24, 2020)

I think you should measure the dovetails with pins and see if its narrower in the middle. I generally don't do high precision projects but now that I see I'm not alone with the loose tight issue I think I may investigate a solution for my machine. I wonder if the column flexes enough in the middle to allow the dovetails to actually bow together when tightening the locks. It will be interesting to see what others have to say. And by the way QMT has been an awesome company to work with for me. I had motor troubles early on and they handled it very well. I knew when buying my 727 that it would probably have some Chinese idiosyncrasies but I have not been upset by them. the machine as is a good value in my eyes.


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## Brad125 (Sep 25, 2020)

tweinke said:


> I think you should measure the dovetails with pins and see if its narrower in the middle. I generally don't do high precision projects but now that I see I'm not alone with the loose tight issue I think I may investigate a solution for my machine. I wonder if the column flexes enough in the middle to allow the dovetails to actually bow together when tightening the locks. It will be interesting to see what others have to say. And by the way QMT has been an awesome company to work with for me. I had motor troubles early on and they handled it very well. I knew when buying my 727 that it would probably have some Chinese idiosyncrasies but I have not been upset by them. the machine as is a good value in my eyes.



I agree, the machine is a good value. I just want to find a solutuon for mine. I am going to upload another video for everyone to view and see what they think, or if there is something else i can try. My lower reciever will be here monday, and machining starts in 2 weeks. I cross my fingers that this will be resolved before then.


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## Brad125 (Sep 25, 2020)

PM just got back to me today, he said to try and shim the gib to see if it helps and also to try and isolate where the problem is. How in the heck do you do about shimming the gib? I heard of shimming straight gibs, but not on a tapered gib like these colums have.


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## Brad125 (Sep 25, 2020)

They also said that they will keep working with me until we figure out what it going on, and do whatever they have to to make it right. Atleast i can rest alittle easier if shimming the gib doesnt work.


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## davidpbest (Sep 25, 2020)

Brad125 said:


> PM just got back to me today, he said to try and shim the gib to see if it helps and also to try and isolate where the problem is. How in the heck do you do about shimming the gib? I heard of shimming straight gibs, but not on a tapered gib like these colums have.


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## Brad125 (Sep 26, 2020)

Awsome video, my next question is how thick of shim would i need? If the head moves .025 thousands when clamped. Should i use half that at .012ish?


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## jaek (Sep 26, 2020)

You said that when the head is at the top or bottom of the column it binds up and won’t move. When it’s bound up, does loosening or tightening the clamp screws move the indicator?


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## Brad125 (Sep 27, 2020)

Yes, but there is less movement, the top clamp moves about .003 and the bottom clamp will move it .015.


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## Brad125 (Sep 27, 2020)

Well just got done shimming it, took awhile, but the results are not good to say the least. After a .011 shim the fit to the column is really tight, so tigh its alittle hard to move. The "feel" is better, but i when the clamps are tightened the head moves .015 instead of .025 like before. I also have to turn the clamps a good bit to tighten, same as before maybe slightly less.


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## jaek (Sep 27, 2020)

Significant drag on the axis happening at the same time as a lot of slop that can be taken up by the clamping screws sounds like a bent gib to me. Have you checked it for straightness? Put it on a surface plate (or even the milling table) and see if it rocks back and forth, makes different sounds when you tap it, or you can see light under it.

None of this should prevent you from using the mill, however. Just lock the Z axis when cutting or indicating...


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## Brad125 (Sep 28, 2020)

Well after a few more emails to Matt and videos, Matt has offered me a few options. I choose to just get a new column and backplate. I applaud PM for his willingness to stand by his products and make the situation right. It will take some time for the new column to arrive but atleast i know the issue will be fixed.


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## Brad125 (Jan 24, 2021)

Just a update on the new column and backplate, still waiting for its arrival. I hope it soon gets here. It’s been since October with a 2 to 3 month wait. I’m on month 4 soon to be month 5. I don’t doubt that all this COVID mess has something to do with it.


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