Any advice on the Flatness and Allignment of the Mill Table, can I do anything

The unused holes in a fixture plate can quickly and cheaply be plugged by using ear plugs.

They also sell silicone plugs used to block holes when powder coating. Those would probably work great if you use air to clear chips.

I'd like to see the warped(maybe) table on a surface plate (or the other way around - a surface plate on the table).

Maybe you could buy some 2-part silicone and mold the plugs right in the modular fixture plate. Then just leave them in until you actually want to use the hole. I don't think getting a molded-in-place silicone plug out of a 1/2-13 hole would be too hard, especially if you use softer silicone.

Silicon Plug & Cap Kit

Ear plugs are cheapest. They last forever in coolant as you know. 100 pairs, 8 bucks.
some coolants eat silicone. Just sayin

They might work pretty well for powder coating too. Thanks for the idea. :)

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Originally Posted by Hirudin

I'd like to see the warped(maybe) table on a surface plate (or the other way around - a surface plate on the table).

Maybe you could buy some 2-part silicone and mold the plugs right in the modular fixture plate. Then just leave them in until you actually want to use the hole. I don't think getting a molded-in-place silicone plug out of a 1/2-13 hole would be too hard, especially if you use softer silicone.

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No need for that. Given the magnitude of the error, simply laying a straight-edge on the table should make the problem quite visible, especially along the diagonals.

Regards,
Ray L.

I am definitely going to try re-shimming the base today. I remember we shimmed the mill to level and then added shim to remove any twist when we first set it up. I think you are spot on that the mill should be totally unstressed when fastened down. i hope any residual stress that may have been in the base from this last year will come out and it will sit unstressed today. But the three point support method should show this because it will have no twist in this state. Tormach emailed me back ans said the same thing. to try re-shimming the base, they also included the excerpt from the manual that was posted below. hopefully this will get it closer. I have even had a crazy thought that what would happen if you got a granite surface plate and had it drilled through with the same bolt pattern as the Tormach base mounting holes and then bolted through the granite and had the mill sitting directly on top. crazy thought i know but do you think it would help at all. There is a $300 2' x 3' granite slab on craigslist in my area (i'm not considering doing it but just to show that the price is not outrageous).

A question i still have is about the tightness of the bolts that hold the machine down. Currently the bolts are very tight from when we first bolted the machine down. I have read that some people have just hand tightened them so no stress is added, this makes sense to me because that is similar to how they are tested at the factory. But i also like the thought that if it is bolted down then the base of the mill can gain strength from the stand. We made our own stand and it has 4 legs made out of 4.5" x .250 wall pipe with a .250 thick top plate and a .375" thick base plate, all of it is steel and the base is anchored to the concrete floor. Each of the pipes are directly under a foot of the mill so the load should be transferred straight down. probably overkill but i like it. If i could gain any strength from it that would be great. How tight did you tighten your mills mounting bolts?

And i really like the earplug idea! that's great, definitely what i will be doing. I wonder if you could plug the threaded holes with them as well, maybe cheaper and faster to remove than set screws :)

Yes threaded also works great

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Originally Posted by EvolveES

I have even had a crazy thought that what would happen if you got a granite surface plate and had it drilled through with the same bolt pattern as the Tormach base mounting holes and then bolted through the granite and had the mill sitting directly on top. crazy thought i know but do you think it would help at all. There is a $300 2' x 3' granite slab on craigslist in my area (i'm not considering doing it but just to show that the price is not outrageous).

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This only works if the four contact points on the underside of the base are in the same plane to a high degree of precision, which on the early models they are not, I don't know about later models.

Phil:)

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Originally Posted by EvolveES

A question i still have is about the tightness of the bolts that hold the machine down. Currently the bolts are very tight from when we first bolted the machine down. I have read that some people have just hand tightened them so no stress is added, this makes sense to me because that is similar to how they are tested at the factory. But i also like the thought that if it is bolted down then the base of the mill can gain strength from the stand. We made our own stand and it has 4 legs made out of 4.5" x .250 wall pipe with a .250 thick top plate and a .375" thick base plate, all of it is steel and the base is anchored to the concrete floor. Each of the pipes are directly under a foot of the mill so the load should be transferred straight down. probably overkill but i like it. If i could gain any strength from it that would be great. How tight did you tighten your mills mounting bolts?

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Just set it up and measure with the bolts loose then tighten the bolts and recheck.

PS: the more rigid your stand the great is its capability to twist the base when you bolt it down. Also a fabricated stand doesn't have the same long term dimensional stability of a cast base so regular checking and adjusting is a must.

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Originally Posted by philbur

Just set it up and measure with the bolts loose then tighten the bolts and recheck.

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Exactly

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Originally Posted by G59

The unused holes in a fixture plate can quickly and cheaply be plugged by using ear plugs.

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That sounds like it could be a really good idea and cheap enough to replace periodically, assuming they are large enough OD to fit the holes. LeeWay's suggestion to use silicone plugs also sounds good, but silicone appears to be more expensive.

Mike

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Originally Posted by philbur

This only works if the four contact points on the underside of the base are in the same plane to a high degree of precision, which on the early models they are not, I don't know about later models.

Phil:)

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I believe that Tormach improved the way base cabinets were made a few years ago so that recent mills suffer from non-planarity in the base/cabiinet mounting pads to a much lesser degree. My early Series I was was woefully out of tram and Tormach suggested shimming it. They also cautioned that the mounting nuts should be little more than hand tight.

Mike

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Originally Posted by EvolveES

I am definitely going to try re-shimming the base today. I remember we shimmed the mill to level and then added shim to remove any twist when we first set it up. I think you are spot on that the mill should be totally unstressed when fastened down. i hope any residual stress that may have been in the base from this last year will come out and it will sit unstressed today. But the three point support method should show this because it will have no twist in this state. Tormach emailed me back ans said the same thing. to try re-shimming the base, they also included the excerpt from the manual that was posted below. hopefully this will get it closer. I have even had a crazy thought that what would happen if you got a granite surface plate and had it drilled through with the same bolt pattern as the Tormach base mounting holes and then bolted through the granite and had the mill sitting directly on top. crazy thought i know but do you think it would help at all. There is a $300 2' x 3' granite slab on craigslist in my area (i'm not considering doing it but just to show that the price is not outrageous).

A question i still have is about the tightness of the bolts that hold the machine down. Currently the bolts are very tight from when we first bolted the machine down. I have read that some people have just hand tightened them so no stress is added, this makes sense to me because that is similar to how they are tested at the factory. But i also like the thought that if it is bolted down then the base of the mill can gain strength from the stand. We made our own stand and it has 4 legs made out of 4.5" x .250 wall pipe with a .250 thick top plate and a .375" thick base plate, all of it is steel and the base is anchored to the concrete floor. Each of the pipes are directly under a foot of the mill so the load should be transferred straight down. probably overkill but i like it. If i could gain any strength from it that would be great. How tight did you tighten your mills mounting bolts?

And i really like the earplug idea! that's great, definitely what i will be doing. I wonder if you could plug the threaded holes with them as well, maybe cheaper and faster to remove than set screws :)

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Good to hear you are absorbing this stuff now. I build my stand with 3 point floor contact so that it doesn't twist when shifted to different floor positions etc. The Tormach stand is very light and will distort as its 4 feet bear the load on the floor. And it will change when it is shifted unless the floor is perfectly level - which it never is.. You really should check the base is not twisted if you move the stand. Sounds over the top? I would have thought so too until I did some tests/measurements. your stand is heavy - that is great, you may be able to improve it further by putting a block on the floor - in the middle of maybe the back - and keep the feet adjusted just short of taking the weight for safety. keen

I mean the reason for the block is to change the floor contact to three point. But if you are bolting down on to the concrete floor, then you wont be moving it and just setting the base stress free on the stand is fine. Re your question re how tight to tighten the mounting bolts and wanting to gain strength from the base....you can put an indicator on each top corner of the base you are tightening to check that it doesn't move - then you can really tighten it, and stop short of that if one is twisting due to uneven surface contact/gaps etc. keen

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Originally Posted by G59

Ear plugs are cheapest. They last forever in coolant as you know. 100 pairs, 8 bucks.
some coolants eat silicone. Just sayin

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Ah, if coolant is going to eat the silicone then it wouldn't be a good way to go. Seems like a lot of people use silicone to seal their stands/chip trays/enclosures though and this is the first I can recall hearing that some coolant degrades silicone.

[edit]
I searched around and found several forum posts confirming that water soluble coolant will degrade silicone. Thanks for bringing that to my attention. Thankfully, I haven't used much of it yet, but that's good to know because it is probably what I would have used in the future.
[/edit]

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Originally Posted by SCzEngrgGroup

No need for that. Given the magnitude of the error, simply laying a straight-edge on the table should make the problem quite visible, especially along the diagonals.

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That was my thought as well, I even recommended it a little bit ago, but I don't know if it was tried. It seems like the question of whether the problem is the base or the table (or both or something else) hasn't actually been answered yet. Is it that the base is all twisted up or is it that the table isn't flat? It seems like everyone wants to jump straight to attempting repairs before the problem is truly known.

It is not a repair to check the base isn't twisted.

Thanks again for all of the input. I got busy making a part until pretty late last night but this weekend a friend is coming over and he will help me check the level of the base, we are going to loosen the mounting bolts, and then try the three point method and then re-shim everything to keep it all in contact. Then we will try to slowly tighten the bolts and see if the tram starts to change. I will report back with what i find. Thanks again

~Zach

Well, we finally solved our issue. It took longer than i would have hoped to get an opening on the machine but this weekend we got it all straightened out.

We started by loosening the base bolts to the table (which we had tightened the S*** out of initially - not good). we trammed the table and the measurements changed so it looked promising. We then removed all of the shims we had put under the base. Then we lifter the front of the mill and supported it with a .75" aluminum block in the center. This holds the table in a three point support and can't flex it at all as many on here have said to do. We then trammed in this position (still with all base bolts loose). It actually looked much better, but when we would get to a certain point the measurement would jump. It turns out the Y gib was now loose (no longer pinched from the base flexing), so i checked the X gib (did not need adjustment) and re-adjusted with Y gib, all while still supporting the mill in three points.

Once all gibs were re-adjusted it was time to re-tram the table...and WOW what a difference it made. We saw 0.0005" across the entire 18" X travel, and no noticeable change in the Interapid indicator across the 9.5" Y travel. we were ecstatic to say the least!

Now it was time to set it back on all 4 feet. We removed the block that was supporting the front in the center and set the mill back on all 4 feet. We trammed the table and saw about 0.0015 across the 18" of X travel and about 0.0006 Across the 9.5" of Y travel. We wanted to do better. Our approach was to lift the front and insert a shim under ONE of the feet and then set the mill back down and re-tram. We guessed the foot right the first time but the shim thickness was too thick (0.030") and it twisted the table the other way. You can tell by the direction of the indicator when you tram the Y on the left edge of X travel vs. the right edge of X travel, we reduced the shim thickness to a 0.010 shim and it was much better, but we wanted perfection. So we changed to a 0.007" shim and that was the one! we have 0.0005" in the Y direction on the left edge, 0.00125 across the 18" in the X direction (both top and bottom of the table), and no real noticeable change in the Y direction in the center and right edges. We decided NOT to tighten the base bolts, and just left them finger tight.

The machine has been running since saturday and i just re-checked it last night and it still trams as good as it did when we adjusted. I will check it again in a few months to make sure.

In addition the center T slot came back to life also, the FRONT edge (the ground one) measures with no noticeable error until the far right hand side two inches, and then it changes by 0.0005", so it looks like we can just set vices and fixtures on for standard tolerance work. and henceforth i will return to calling the center slot a "Precision center slot" :)

I was so used to working with the crooked table that everything we have made since has seemed like cake, many of them coming out within +/-0.001 in Z depth across the entire thing (usually 10.25"). So at the very least i may have gained some skills trying to compensate for the crooked table for the last several months lol

Sorry if this was long winded but i wanted to document what we found and hopefully our struggles and what we learned will be of use to someone in a similar situation in the future.

Thank you again everyone for all of the helpful input and suggestions while we were trying to figure this out.