Tramming a bench top mill.. Y-Axis

Pcmaker said:
I don't have a cylinder square, just a regular machinist square. I'll mount an indicator on the headstock and run the Z axis up and down the square to see if the needle moves. Unless I'm misreading your post.
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The most accurate method of tramming a mill is to use an offset indicator in the spindle. Regardless of any runout issues, the indicator is necessarily rotating around the spindle axis so the indicator tip traces a path in a plane perpendicular to the spindle axis. Resolution is as good as the resolution of your indicator. The issue of the non-parallel table does exist in this method and it also would exist using a cylindrical square.

If you have a fixed spindle as the Tormach has, the spindle axis must be aligned parallel with the z axis ways AND the z axis ways must be perpendicular to the x and y axis ways. As Robert said above, it is possible to align then so two offsets cancel and the tram is perfect.

My round column mill/drill, on the other hand, has a movable quill and for all intents and purposes the head is stationary. Tramming can only be accomplished by shimming the column. If you have a mill where the head can be rotated in the x-z plane, You could tram in the x direction by adjusting the angle of rotation. You could also do so by shimming the column but it would be ridiculous to do so. If your mill has nod capabilities, you can adjust y direction tram in the same way.
 
PCmaker,
Welds (even tacks) will shrink as they cool and distort the accuracy of your tramming.

There is a product (at least there was awhile back) that is liquid/putty like and is forced into the gap between the column and the base after it is shimmed/adjusted to the desired position. It is said to dry very hard and without changing dimensions. It is (was?) made expressly for tramming mill columns and the like. I don't have a clue as to name, supplier or anything else though. Google I guess!
 
I'm trying to tram the X axis right now. So, I move the table all the way to the left zeroed the indicator, then moved all the way to the right. The difference is .007 thou

I then tapped the head to where the indicator shows .0035

Is this the right way to do it? I just did it, then moved all the way to the left and it still seems like I still have that much of a difference. What am I doing wrong?
 
Pcmaker said:
I'm trying to tram the X axis right now. So, I move the table all the way to the left zeroed the indicator, then moved all the way to the right. The difference is .007 thou

I then tapped the head to where the indicator shows .0035

Is this the right way to do it? I just did it, then moved all the way to the left and it still seems like I still have that much of a difference. What am I doing wrong?
Click to expand...


I might be miss understanding, but it sounds a little unconvetional. I think ur reading flatness errors.

Normaly a dial indicator goes on a long stick mounted in a collet in the spindle and is swung around to cover a circle area that fits on your tabStu

Also as somone else mentioned, you might be seeing sag from gib looseness or possibly spring if u have anything bolted down in the t slots.

Stu
 
stupoty said:
I might be miss understanding, but it sounds a little unconvetional. I think ur reading flatness errors.

Normaly a dial indicator goes on a long stick mounted in a collet in the spindle and is swung around to cover a circle area that fits on your tabStu

Also as somone else mentioned, you might be seeing sag from gib looseness or possibly spring if u have anything bolted down in the t slots.

Stu
Click to expand...

Yep, I made something like that. It swings through the spindle. I zeroed it on the left side, swung it to the right, and it's off by .007

If I tap the head, what should I aim the indicator to be? I always though it was half the difference from the left to the right.
 
Pcmaker said:
The thing on the side is a good idea. Instead of tapping with a rubber hammer, you can just turn on the set screw to move the head of the mill.
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Yes I did that mod to my g0704 mill many years ago. Works great. One on each side. when I need to cock the head just loosen them up and swing them out of the way.
 
Pcmaker said:
Yep, I made something like that. It swings through the spindle. I zeroed it on the left side, swung it to the right, and it's off by .007

If I tap the head, what should I aim the indicator to be? I always though it was half the difference from the left to the right.
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That’s correct. Keep splitting the difference until it’s as close as possible.
 
MSD0 said:
That’s correct. Keep splitting the difference until it’s as close as possible.
Click to expand...

I've been doing that. I get to half, then go back to the left, re-zero, then I go right, and it's still off. After doing it 3 times.

I'm going to put in a set screw to push the head back and forth instead of me tapping with the hammer and see if that does it.
 
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