[tmarks11]

My second issue is when i measure the edge of the center precision T-slot i am getting a variation of 0.0115", i have always wondered why the vices we use will not align with the keys in them.

Which is why a lot of shops with professional level equipment don't rely on vise keys to align their vise. Sweeping a vise with a DTI to align within 0.001" should only take you 2 minutes (with some practice). I bought a set of keys (DAMW), but haven't even bothered to install them to see if they work.

Why do you call it "precision t-slot"? It looks like it is milled, not ground, just like any other (non-precision) t-slot I see on other machinery.

wrt to table flatness... I am thinking it is not that the table is not flat (although that might be true), but is that the head or column is out of tram.

I don't agree with all of the approaches John took in the video below, but what he did works... and you can see an amazing change in indicated readings from a pretty simple process:
https://www.youtube.com/watch?v=lle-k_ccFAA

[SCzEngrgGroup]

I am thinking it is not that the table is not flat (although that might be true), but is that the head or column is out of tram.

Tram cannot explain the table appearing to rise and fall as it's moved side-to-side. That can only result from either the table being thicker or thinner, as measured from the table surface to the horizontal portion of the ways, at various locations, or the machine base twisting, a LOT, as the table is moved. The Tormach base is a big, beefy casting, and it's not going to move significantly just due to the weight of the table. You can tilt the column 10 degrees, and a dial indicator in the spindle should show no rise and fall of the table surface.

Regards,
Ray L.

[tmarks11]

Tram cannot explain the table appearing to rise and fall as it's moved side-to-side.

Maybe my reading comprehension sucks, but I didn't get that from his post. I didn't see anywhere where he talked about dips or valleys.

The worst of the variation seems to be from the top right to the bottom right corners, it is going from -.0035 to +.003 when compared to the top left (that's a total variation of 0.0065" over 9" of Y travel!)

Sounds like a two-dimensional tramming problem (tram error in X and Y). Before grinding the table, I would see if I could solve by shimming, attacking one dimension at a time. Much easier on a bridgeport.

[instructor37]

Tram error would show up if he were sweeping his indicator in a circle over the table. With the indicator held in a fixed point above the table and getting a variation as the table moves under it indicates the table is not flat.

[EvolveES]

Thank you for all of the great advice everyone! To answer a few questions i was moving the Z up and back down each time because i wasn't sure about dragging the tip of the depth gauge, i will repeat the tests with an Interapid dial i have. with the Z backlash at <.0005 i don't think it would be too far off to move it up and down (at least compared to the 0.006 i'm seeing).

I think for me a surface plate would probably work best, i am thinking about shimming it up with as thin of shims as possible to keep good contact with the table and preserve Z height, and then plug all of the holes with set screws. I like the idea of making my own but that limits me to just a little over the 9.5" x 18" work area of the tormach if i want to keep it true (i fear if i move it and resurface it will not be consistent due to the warp in the table. Tosa sells a aluminum tool plate for like $500-$600 but i wonder how much i would ding it up setting vices, turn tables, and other heavy fixtures on it.

Looks like i should start saving up for the Tosa Tool Plate lol in the mean time i am going to tram it again and double check the shims under the feet, spindle squareness etc and see if i can find any other culprit.

Thanks again everyone, this is one of the most helpful forums i have been on!

[cncoperator]

Thank you for all of the great advice everyone! To answer a few questions i was moving the Z up and back down each time because i wasn't sure about dragging the tip of the depth gauge, i will repeat the tests with an Interapid dial i have. with the Z backlash at <.0005 i don't think it would be too far off to move it up and down (at least compared to the 0.006 i'm seeing).

You're introducing all kinds of possible issues when you move Z up and down. It's even possible you have a Z axis issue and not a table one. There is no problem with dragging the tip as long as it only drops down slightly or you carefully move it up with your finger when crossing a T-slot. The few grams of force the plunger is exerting or the tiny force on the plunger housing isn't an issue.

[EvolveES]

You're introducing all kinds of possible issues when you move Z up and down. It's even possible you have a Z axis issue and not a table one. There is no problem with dragging the tip as long as it only drops down slightly or you carefully move it up with your finger when crossing a T-slot. The few grams of force the plunger is exerting or the tiny force on the plunger housing isn't an issue.

That is good to know, i think i will try with the indicator and just lift it up over the T-slots, I hadn't really thought it could be a Z height issue because i have made a lot of small parts and hit the Z depth to +/-0.001 pretty routinely, but it does make sense now that a disconnect in the Z DRO and stepper could show the same error. I'm going to check it out again not moving the Z.