Tramming a bench top mill.. Y-Axis

[rwm]

You are doing it correctly by rotating an indicator in the spindle. That will work. Yes half the difference in readings.
Since your mill has a movable head on the Z as well as a spindle I was trying to make the theoretical point that a cylinder square could isolate these. That is probably overkill for your needs. I have seen some people use a large bearing race on the table and run the indicator on that to avoid the T slots. That seems like a great idea if you can find one in your travels.
RJ that is a clever solution to your off parallel table but seems like a real pain. How often does that problem occur on a quality machine like a Tormach? Did you consider getting the table ground flat?
Robert

 

[ThinWoodsman]

I don't have a cylinder square, just a regular machinist square.

Easy enough to turn one out on the lathe:
http://homews.co.uk/page307.html

 

[Pcmaker]

I got the X axis down to .003 and the Y axis down to to .004

I'm having problems after tramming the X axis. When I tighten down the nuts to lock down the head, the indicators move. I'm thinking of keeping the nuts tighter so the head doesn't move as much when I tighten the nuts.

or should I compensate for the head movement when I'm tightening down the nuts. Or both of these. There's 3 nuts that lock down the head's X axis.

 

[MSD0]

I got the X axis down to .003 and the Y axis down to to .004

I'm having problems after tramming the X axis. When I tighten down the nuts to lock down the head, the indicators move. I'm thinking of keeping the nuts tighter so the head doesn't move as much when I tighten the nuts.

or should I compensate for the head movement when I'm tightening down the nuts. Or both of these. There's 3 nuts that lock down the head's X axis.

Are you tightening the nuts a little at a time (after checking with the indicator) or all at once?

 

[Pcmaker]

Are you tightening the nuts a little at a time (after checking with the indicator) or all at once?

Yep, little at a time, still moves. I think I had the nuts on too loose. I'll try again today.

I'm using one of these to tram the mill

 

[astjp2]

Can you post a few pics of your machine? That seems to be off a lot still. It almost sounds like the table is not of the same thickness.

 

[yendor]

You should be tightening down the column nuts with a torque wrench otherwise you will find yourself chasing ghosts.

Tighten them in steps - IE:
Alternating corners at #15
Then add #10 and tightening all (4) again starting with a different corner.
Then add #10 again for a total of #35 and tightening all (4) again starting with a different corner.
Working around the bolt pattern will give you the best even torque on all (4) Bolts. - DON"T always start with the same bolt.

Once all the bolts have been torqued down - That is when you take your measurements.
Record the values and determine What (how thick) and Where you might need to place shims.
You have to be sure you have LOCKED the Table Gibs down on BOTH X & Y Axis.
And LOCK the Spindle Vertical Travel when measuring.
The TABLE does NOT need to be and should NOT be moved to tram the HEAD to the Table.

If all the moveable parts are not locked down when you measure you are just chasing ghosts.
The TRAM is simply getting the Spindle set Vetical - Right Angles both side to side and front to back.

When making up the shims for a machine that is trammed via the column bolts you would be best off to make "U" shaped shims that go around the corner bolts.

I used cutup peices of a soda can.
To make the shims without having burrs on the edges I made 8 peices approx 1-1/2' square.
Sandwiched them between (2) peices of 1x3 clamped it down on my drill press and drilled a 7/16th hole thru them all at one time.
Then I used a pair of avation type metal snips to cut out the "U"
Lastly I sanded them lightly to remove any burrs from the snip cuts.

 

[Pcmaker]

Can you post a few pics of your machine? That seems to be off a lot still. It almost sounds like the table is not of the same thickness.