Tips on tramming the nod of benchtop mill PM25MV

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Wonderclam

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I have a PM25MV mill. I'm using Edge industries tramming tool. It goes in the spindle and has 2 indicators on both sides. I calibrated it until I got it to about .0002

I trammed the X axis and got to around around .001. Good enough for me.

Now it's time to do The Z axis and it is off by .006

So I decide to shim it. I added .006 feeler gauge on the left and the right side of where the front bolts are.

Then it was off by .009. so I redid the shims to .009.

Then it was off by .012. so I redid the shims by .012.

Then I needed to take off .009 from front, then I took off all the shims.

Now, I'm off by .007...

You see where I'm going with this. Anyone have this mill and have some tips?
 
start with a smaller gage, .002" or ,003". it doesn't take much to move it.
 
Wonderclam said:
Now it's time to do The Z axis and it is off by .006

So I decide to shim it. I added .006 feeler gauge on the left and the right side of where the front bolts are.

Then it was off by .009. so I redid the shims to .009.

Then it was off by .012. so I redid the shims by .012.
Click to expand...

So if it was off more after you shimmed it the first time, why would you use even thicker shims, and then do the same thing a second time?
 
You need to remember that the Y axis is not directly in line with the spindle and that a small shim at the column will make a large change at the spindle.
 
Which was lower when you started and then after each new set of shims… front of table or back of table?
Were all sets of shims in the same spot?
Where exactly was that spot relative to the bolts and the front or rear edge of the casting?
Pictures of the shim locations would help us see what you see.

Tom
 
The back was lower by .006 at the beginning. When the front indicator was at .050, the rear one was around .043.

I'll take pictures and post them in a little bit
 
so this is where I've been adding the shims. and I add another shim of the same thickness on the same spot on the other side of the mill

n2SzPBt.jpg
 
The Pro Tram has a separation of 5" between the indicators so your original difference is .006"/5". It looks like you would be about half that distance between the pivot point and your shim location at the base of your column so the required shim will be .006"/5" x 2.45" or .003". From your description, it sounds like you shimmed the wrong end.

One thing that you have to remember with your type of mill is that a loose column gib will cause head sag. You should always lock the column when you are tramming.
 
Bah, it's off tram again after a little bit of work. Not sure what happened, everything was as tight as can be. Very discouraging.
 
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