I'm curious about my mill tram

[Aukai]

I put a Copmac 513 10ths dial indicator in a collet chuck. Full X travel on a 50" table with 0 to the right +.002. If I split the table 0 the indicator, and go 12" table right I get +.0005. I return to center, and 0 repeats, then 12" left I get +.001. My noodle is not comprehending, I thought I saved a traming guide from here but cant find it. The Y in, and out is less than .0005.

 

[mksj]

That is about as close as you are going to get on a 50" table. Should also be a spec sheet with actual values and tolerance

 

[Aukai]

I do have that, I'll look at it tomorrow. All I've done is cranked the head back to the 0, and this is the reading, much easier than the Grizzly actually. My machinist square looks pretty air tight against the spindle on the X, and Z too.

 

[Eddyde]

As you crank the table away from the center it will start to drop from the increasing weight on that end thus the spot under the spindle will rise.

 

[Asm109]

To me, tram means the spindle axis is perpendicular to the table top. You are measuring how parallel the table top is to the ways. You also capture any slop in the ways (there must be some) as the table weight gets overhung at the extremes of travel.

 

[Winegrower]

I agree with Asm109. No matter the head inclination, just holding an indicator and moving the table past it will show 0 change if the table is flat, but won’t measure anything about head alignment.

 

[MrWhoopee]

Agree with the others, tram is considered to be perpendicularity of the spindle to the table. What you seem to be checking is the repeatability of the table travel. For the distances you are measuring you really can't expect better than what you are seeing. That's why they made jig borers.

edit: using a precision square against the quill is a good place to start tramming the head, but it needs to be finished by sweeping the table with an indicator.

 

[markba633csi]

Remember too that tables can warp from the action of the t-bolts stretching the metal of the slots.
Good reason not to overtighten
Your measurements are actually quite good for a table that long
-M

 

[Aukai]

One of the dial indicators on the Edge Pro Tram is broken, I've used it only a couple of times. The bezel separated from the face, and won't 0. My Noga spindle mount has a kinda short sweep, but I'll see what I come up with. Thank you for the replies.

 

[Aukai]

So, I trammed the X, then the nod, and X went out. I got it back, and have a 0 sweep 360*,. The Noga only has ~ 5" of sweep, hopefully that does it.