Pm932m-y Tram Off .003 Over 4"-y Gib Adjustment?

[Gburgswmich]

Hello all, and thanks to those sharing their knowledge and experience be to help beginners like myself!
My PM932M is barely broken in, but I need to get everything square! I checked my column to spindle, and it is perfectly square. The spindle to table however is off .003" over 4". The front of the spindle is sagging the .003 over 4". Is this something that can be fixed without shimming the front of the column? Is there a particular gib adjustment anyone would recommend? Again, I'm as green as they come, and forgive me if I haven't come across the answer through searching. I'm hoping someone can answer me here. I thank you all in advance. Greg

 

[tmarks11]

You are not going to like this answer, but... you really need a DTI, some holder to keep it in the spindle (like a Noga), and a cylindrical square.

There are two different shims that you might have to do.
1. Column to base (I know you said this isn't the case, but I am doubtful of any measurement made that doesn't involve a DTI).
2. Head to column slider

The trick is to figure out which one. For that, you need a cylindrical square.

If the problem is #1, than with a DTI (Dial Test Indicator) in the spindle, as you raise the spindle, the DTI measurement against the vertical face of the cylindrical square will change. If the problem is #2, the DTI measurement will be unchanged as you raise the spindle.

You can shim will aluminum foil, which is a convenient thickness.

I wouldn't mess with either adjustment until I knew for sure what it was. And I don't know a good way to figure it out without a cylindrical square, since you have to measure for Y position change in the DTI as you raise the head.

 

[Gburgswmich]

I followed Hossmachine's guidelines and use a magnetic base attached to the column to measure runout in a precision rod in the spindle. The runout in both the x and y ended up being 0 after adjustment.
Using a spindle square, I came up with the spindle to table measurement. The above test should rule out the head to column I believe??.....

 

[dave2176]

Can't argue with Tim's answer. He's dead on. Make sure the Z gib is adjusted right so it doesn't add to your measurement. It's fairly common to need to shim the column to get it perfect.
Dave

 

[Gburgswmich]

I'm Using a starrett magnetic with interrapid DTI reading the runout on the precision .5" carbide rod in the spindle. Took readings at the top and bottom of the rod and fixed it to zero runout.
I don't think I know how to properly adjust the Z gib. That's was my hope was to make my adjustment there to fix this Y deflection. Maybe I'll mess with this some more. Just when I thought I purchased all the tools I needed to tram properly, now there's a cylindrical square

 

[Dan_S]

before you but a cylindrical square, try this first.

1. mount your carbide rod in the spindle.
2. extend the quill 4" and then lock the quill in-place with the quill lock.
3. lock head in-place
4. take a dti or a good 0.0005" indicator and mount it to the column so you can indicate close to the spindle
5. indicate close to the spindle and note the highest & lowest value in the x direction
6. loosen the head and carefully raise it (don't move the indicator)
7. lock the head down again and then carefully indicate on the end of the shaft just like in step 5

Use rollie dad method to calculate if the head is out of tram to the column .
Repeat 5, 6, & 7 in the y direction.

Once you know how far you are off from the above, you can either live with it of fix it.


To check against the table just sweep it like shown in a million you tube videos. If you haven't fixed the above, you can factor it out when sweeping the table.

 

[Gburgswmich]

The Rollie dad method is exactly what I did to find out the head was square to the column. Hoss machine's video on his g704 tramming is what I followed. Sorry if I wasn't clear in saying that in my intro.
The head is not square to the table, so methods other than shimming the column are what I was hoping to find here

 

[Dan_S]

what video did you follow, because several of his videos have errors in them.

 

[tmarks11]

I followed Hossmachine's guidelines and use a magnetic base attached to the column to measure runout in a precision rod in the spindle.

Hoss' technique has some short comings, but in the absence of a cylindrical square (which isn't cheap), this should get you what you need. The precision drill rod in the spindle to the column DTI tells you the head is aligned to the column (assuming you rotated it to ensure that measured values were not affected by run-out of the collet, which frequently can be 0.002"+).

That means that any error found after that when sweeping the table (or using your double indicator spindle square) should then be column to base tram. This can be caused by grit or paint chips in the mating surface. Take the column off, clean up the mating surfaces, vacuum out the casting (sucks when casting sand falls out of the column on the base when you start putting it back together and you find you are further out than when you started), use blue painters tape to pick-up any grit off the mating surfaces, re-mate them and measure again. Then take it apart again and start shimming.

Note about z-axis gibs. Head droop due to gibs too loose would have shown up on your head-to-column measurement. So I would't tighten the gibs.

 

[Dan_S]

Hoss' technique has some short comings.

That's an understatement. Telling people to not use the ball on a dti is unforgivable.