# Pm 727m issues, help please!



## Brad125 (Aug 12, 2020)

Hey fellas,

 I been fighting my machine for hours. If i have the.Z axis locked down and indicate the X axis( .0002 over 10 inches) as soon as i raise the Z axis a few inches lock down the Z axis and try again, the table is way off. Like 5 or 6 thou off. I have the Z axis gib adjusted tight but not to tight, there is a 1/2 inch of gib sticking out fron under the head of the mill. What in the heck is causing this? Its driving me nutz!!!  I am using an Edge Technology indicator holder and a Browne and Sharpe BesTest indicator and using precision 123 block accuracy to .0002. Anybody have any ideas? I thought square column mills were suppose to hold the position when raising and lowering the head?


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## T Bredehoft (Aug 12, 2020)

Can we assume that the column/head is clamped when setting zero, and also clamped when moved and re-indicated?


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## markba633csi (Aug 12, 2020)

You mentioned the 1/2" of gib sticking out- that sounds wrong.  If it moves as you move the head you need to investigate that.  Usually, on non-tapered parallel gibs there are dimples in the gib that engage the adjustment screws to keep it from sliding around. 
-Mark


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## Brad125 (Aug 12, 2020)

I believe this machine gas tapered gids, and yes the machine Z axis is locked down before indicating. Something doest seem right and i can figure it out. The 1/2 inch on gib sticking out the bottom is from having to adjust it enough to take the slack out, or maybe someone else has a procedure they would be willing to share.


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## parshal (Aug 12, 2020)

I had a similar issue on my 833TV on the X axis.  I had to cut the gib because I had so much sticking out.


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## Brad125 (Aug 12, 2020)

Gutting the gib off is fine with me, i just want to know whats causing the head "tilt" to be off that bad when traversing the Z Axis


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## JRaut (Aug 12, 2020)

Sounds to me like your column could be out of plumb.

Are there any adjustments on that? Or have you checked it for squareness recently?


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## Brad125 (Aug 12, 2020)

The only adjustment is head tilt, i know thw machine has a nod of .004 but that shouldnt affect the squareness to the table at various distances. I have not checked the squareness for the head in relation to the table, the only way to do that is to extend the quill the 3" and run it up and down a angle plate, which i dont have one currently.


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## markba633csi (Aug 12, 2020)

I would bounce it off PM and see what they say- Maybe they will send a new gib strip or give some adjustment info
Ask them what the maximum repeatability deviation of the head is when traversing vertically
-Mark


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## Brad125 (Aug 12, 2020)

I will give them a call tomorrow and see what they say...


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## Brad125 (Aug 13, 2020)

Well i didnt get a chance to call PM today, but i was watching alot of videos last night and i think the problem might lie with the mill head not being "square" to the column. This would explain why tram moved when i lower and raise the head. Of course if i square the mill head to the column then instead of tiling the head to tram, i would have to shim the column base.


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## GunsOfNavarone (Aug 15, 2020)

I bought a good tramming tool for my pm727m, made it much easier and faster. It WAS slightly off but that could be existent you're dealing with. That Z axis gib is a but complicated. If you tighten the top you need to loosen the bottom so there is pressure on both sides. The complicated part is getting to the lower gib adjust. You have to slightly pull the bellow away from the column top left (opposite side of quill controls. A tight gun just means your tightening against the opposite side adjuster, not moving it at all. I apply it you've already done this. 
I'd recommend the team took tough....


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## Brad125 (Aug 15, 2020)

Yes i alread adjusted the top gib for z axis, i actually lowered the spindle on about 4 or 5 hockey pucks to take the pressure off then completely loosened the bottom screw, then i tightened the top one till it started to get tigh then just back off alittle and tightened the bottom screw.


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## Brad125 (Aug 18, 2020)

Well i went and bought a long 3/8 drill bit and cut the shaft off to give me about 6 inches sticking out of the collet rigged my indicator up in my vise and squared the head to the column to within +_.0005 by moving the head up and down while utilizing a torque wrench set at 50 inch pounds to get a consistent clamping pressure. Here come the baffling part, when i put the indicator back into the spindle after indicating the head to the column, i lowered the table to sweep with the indicator. The X axis is off .0038 in 18 inches!!!! Seem like alot doesnt it?


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## JRaut (Aug 18, 2020)

It still sounds to me like the column is not square to the base.

If there is no adjustment mechanism on the column, you'll need to shim. (Or scrape, I suppose. But probably best not to get into that sort of thing.)

You can use the 0.0038"/18" to get a first guess as to the thickness of shim required. I don't know what the bolt spacing is on your column, but if it's say 6", you'll need to shim about 1 thou.


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## GunsOfNavarone (Aug 18, 2020)

Shim it!


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## MikeWi (Aug 18, 2020)

Sounds like the nod is off to me too. The trouble with the gib is that we can replace it for free, but it will be over-sized and you'll have to fit it to the head's saddle. If it's working as is, I'd just cut off the extra bit. Eventually the gib will wear to the point that the top screw won't be able to prevent it from moving and you'll have to replace it.


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## Brad125 (Aug 18, 2020)

Sorry i had a typo. Its not off .0038 , i meant to put .038.


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## GunsOfNavarone (Aug 18, 2020)

Well, if its side to side and your head is locked @ 0* (assuming the scale is correct) then shim it. I'd be curious if you just tap the head a little to one side (on the tilt scale) and recheck everything (front to back, side to side) if that's the culprit. Zero is always "0".


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## Brad125 (Aug 18, 2020)

My machine does have a .004 nod in it, which i intend on shimming but i need to address the x asis first, then ill add shims to bring in the Y axis. My concern with shimming is losing rigidity of the machine base? I loosesned the Zaxis gib, i never move the Z axis while machining so it is always locked in. So, ill have to add .019 worth of shims to the column base then? Anyone else have to add this much? Just seem like alot....


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## JRaut (Aug 18, 2020)

It's probably worth sketching things out and posting on here.

I, for one, am getting confused about what you've aligned/squared, what you've not aligned/squared, which components cannot be adjusted without shimming, and which way out of alignment things currently sit. And why is everyone talking about gibs? Unless they're super loose, not sure why adjusting the gibs would have a sizable effect on alignment.

A sketch would probably benefit you as well to figure out where the misalignment is coming from.

38 thousands might as well be a mile.


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## Brad125 (Aug 18, 2020)

Ill make a video tonight and see if i can post it on here....


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## GunsOfNavarone (Aug 18, 2020)

You may never loosen/ change head tilt, but if the machine takes a big enough bite it can tip it a bit, not to mention, setting it up (I assume you used a cherry picker?) can twist it a bit. I agree jraut, as long as gibs are snug, it's not that, but I think the thread moved away from that culprit. You DO NOT want to shim the column  it if the tilt is coming from head.


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## Brad125 (Aug 18, 2020)

Well i squares the head to the column by using drill rod about 6 inches long indicated the top and bottom of the rod while the Z axis was tightened down at both positiobs. This is they only way i know how to tram the head.


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## GunsOfNavarone (Aug 18, 2020)

This is a time saver, easy as pie and no frustration. Glad you got it all "squared" away!
Edge Tech Tram


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## Brad125 (Aug 24, 2020)

Well i got the machine leveled, tried using a piece of drill rod in the collet and that didnt work. Took the gib out and cut half inch off, so i could tighten the gib more, still didnt work. Every time i tighten the clamps in the Z axis it throws the head way off, even when it is clamped in different positions. I called PM and the fella i talked to seems to think i may have a bad gib but is going to talk to matt to see what could be causing the issue. So, hopefully i will hear back from them soon.


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## GunsOfNavarone (Aug 24, 2020)

I had similar with my PM-727..PM said it was normal. Something weird is up there...


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## Brad125 (Aug 24, 2020)

I hope its not normal, i could live with .002 but not being out .008 everytime i use the clamps. I can see the head nod get lifted up also when i tighten the Z axis clamp. Another odd thing happenes, when i tighten one clamp it will loosen another. I just have to keep going back and forth until both are tight. I just want to figure out a solution. I have work that needs done and i cant do it with the mill being out so far out of square.


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## GunsOfNavarone (Aug 24, 2020)

Yup. That's my method as well, one then the other,back to the first then the other. This is all I could come up with to fell better about the situation...I trammed it after locking it down with this method, as long as I use this method when machining with it, I should be good. I can probably dig out my emails from PM and post it if you like.


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## GunsOfNavarone (Aug 24, 2020)

Here you go...this was about 2 years ago. I did find a way to tighten gibs a gnats hair but....

> I wrote previously and never received an answer.I have a Pm727m and when indicating off the quill, when I tighten the gib locks on the Z, I get somewhere around 30 thou in movement. I tighten the gib as much as possible and it made zero difference. I could really use some ideas as to where to look issues. I cannot detect and movement by hand between quill and Z column but tightening the gibs sure shows it.
> Thank you,
> Sean 

Hi Sean,

It sounds like you're saying that when you lock the head down, it's
moving. This would be normal as you're pushing on the head when you lock
it down. You wouldn't be setting up work until the head is locked in the
first place, so this movement should have no effect on your accuracy.


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## Brad125 (Aug 24, 2020)

Yea he is right, IF you dont have to move the head. But if im running a end mill, then have to switch to a drill chuck, guess what i have to lift the head which means i loose zero. Unless indicate the head in everytime you move the head the zero will shift. Having to indicate the head in everytime you make a tooling change would be frustrating, and you would have to have a bunch on really long indicator holders to tram X axis everytime. There has to be a fix for this. If i only knew what was causing it. Did you ever figure out what was causing this in your mill or what you did to fix the issue? I have had really good customer servise from PM so far, they are one of the only companies that dont treat me like a idiot when i call them. I have 2 years of machining technology schooling and numerous years in the workforce for machining, on both manual and cnc machines. So, when i call with a problem that means i have already tried everything they are about to tell me. I am hope full i will get an answer or a possible fix from PM. Matt is a great guy so im not worried yet, i just want to be able to use the Z axis without the headache.


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## GunsOfNavarone (Aug 24, 2020)

Well, that conclusion I came to was on my own. They just said it was normal. But if you tram your head with it locked down, I would assume at any height you change it to, relock down, you should still be where ever you were as far as square. Are you saying the amount it shifts is different based on where you're located vertically?Mine seemed to always shift the same amount as long as I did the tightening procedure twice on each gib lock.


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## Brad125 (Aug 24, 2020)

Yea, unless i have the gibs unlocked, then it seems to track ok. Its only when i lock the gib that throws the machine out.


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## GunsOfNavarone (Aug 24, 2020)

Well, please let me know what you hear from PM. I'm guessing they say your machine is off UNTIL the gibs are locked tight....that that actually PUTS the machine into alignment.


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## Brad125 (Aug 25, 2020)

Thats the problem, if this was the case i dont get why when trying to tram the head square that i cant get it to 0 in when indicatee in at 2 different positions in the Z axis when its locked down. I have a precision square coming, but i was fiddleling with it tonight and droped my brown & sharpe bestest indicator and broke the tip off. Its always something, now im gunna have to buy a new indicator before i can try this other method.


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## GunsOfNavarone (Aug 25, 2020)

Oh Man! Sorry to hear that. Hopefully PM come through for you.


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## Brad125 (Aug 26, 2020)

I hope so, i am still waiting for a response from them.


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## COMachinist (Aug 26, 2020)

Did you get a video or some pix so we see what it is doing?
CH


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## Brad125 (Aug 26, 2020)

Nope, i broke my indicator while running another test. Guess i learned my lesson, first and only indicator i have ever droped. I got into a hurry and it slipped right out of my fingers, droped onto my cement floor, broke the tip off and bounched about 4 times. After a few good words i picked it up put it on display and ordered another indicator. I try not to think about it to much, lol.


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## Brad125 (Aug 29, 2020)

Still waiting for a responce from PM, but after hours with an indicator it took .025 worth of shims to bring the column up square left and right. Took another .010 if shims to lift the column up vertically. So now the column is "0" ONLY when the clamps are tight. The head its self still has .005 of nod, and after traming the head to the table there is still error in the X axis, 1" is 0, 2" is .005, 3" is .008 and keeps going up as the head moves up. The spindle travel also has .005 of angle deflection as you turn the handle. Having to shim so much leads me to believe that i will loose to much of the rigidity of the machine. I think i am going to take the shims back out and say the heck with it.


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## COMachinist (Aug 30, 2020)

Yea the shims is worse than none at all. Check out this 



 I did this to my PM 932 m PDF to fix the nod of about .006. I then put a new hand scraped gib in so i had no change in tram with the camp tight or not. I have vowed to never buy an other chines column mill again. I have 2 and both was horrible for tram. After hours upon hours of scraping dovetails and gibs i now have a cnc conversion and a  manual mill that I can do some repeatable and accurate machine work with. I am looking for a nice old BP for real mill work.then I’m selling the PRC junk and doing some fun milling Work. You should do the same Look for a Clausing mill on Craigs list if you don’t have room for a BP. 
CH


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## Brad125 (Aug 30, 2020)

I set it up to start milling, i have 2 jobs to do that cant wait no longer. The mill will stay shimmed until i am done. Then ill prob take the shims out and after that i dont know, cant sell it yet though. I though square column mills were suppose to be so much better than round column mills? I guess each has its own set of headaches.


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