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

Hello,

I have read this forum for years and just recently joined. This last year we got a Tormach PCNC1100 Series 3 and i have enjoyed every chip i have made. I've gotten comfortable with Mastercam and getting the machine to do what i want but now we are getting into some work that would routinely call for +/-0.002" and i have noticed some problems.

We haven't had much difficulty hitting +/-0.002" on smaller parts held in the vice, but i am worried about making larger fixtures for larger parts with the issues i am seeing. The main one seems to be the flatness of the mill table. If i put a depth gauge in the spindle and zero it at the top left corner and then check other points on the table i am seeing some variation. 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!). Is there anything to be done about this? I have leveled the machine with shims under the feet and this seems to be the closest it wants to get to flat.

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. Is there any adjustment that can be done for this? I am debating running an endmill down one edge of the slot to straighten it, but that will only get the 18" that the mill can travel...still may be better than it is now though.

My best solution i can think of for all of this is to get a Tosa Tool Plate and level it in the Z direction with shims under it, and then align it to the X travel and do all of the fixturing from there?

Other than that the machine seems to be in great adjustment, all backlashes are < 0.0005" and the spindle nose runout is < 0.0002

Thank you for any help :)

Have you checked tram on your mill? My very early Series 1 was out quite a bit and I corrected it by shimming the four corners between the mill base and the top of the cabinet.

Mike

If a dial indicator in the spindle shows variation in height as the table is moved around, that suggests the table itself it not consistent height w.r.t. to the ways. One way to fix that would be to remove the table, and have it ground, referencing off the ways. That should get you near perfect. The crooked T-slots could be fixed at the same time. The whole thing would be fairly quick, and should not be hideously expensive - certainly much cheaper than a Tosa tooling plate! Removing the table is not fun, but not really all that hard either.

Regards,
Ray L.

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Originally Posted by EvolveES

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.

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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

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Originally Posted by tmarks11

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.

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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.

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Originally Posted by SCzEngrgGroup

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

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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.

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Originally Posted by OP

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!)

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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.

"i am worried about making larger fixtures for larger parts with the issues i am seeing. The main one seems to be the flatness of the mill table."

I read his explanation as saying that the Z distance from spindle nose to table top surface varies, based on table position, by as much as +/-0.003".

Regards,
Ray L.

I ALWAYS use soft jaws in my vise. I will indicate the vise straight and then machine a step in the jaws and I get a surface that's parallel to the axis of the machine.

I took the steel jaws out of my vise right after I got it, so it's probably been 3 years since I started using aluminum soft haws. For the price I get them for, I won't be going back to steel jaws any time soon.

When I get a job that requires a stronger jaw. I'll make some out of 7075 aluminum. The jaws I buy are made from 6061.

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Originally Posted by Steve Seebold

I ALWAYS use soft jaws in my vise. I will indicate the vise straight and then machine a step in the jaws and I get a surface that's parallel to the axis of the machine.

I took the steel jaws out of my vise right after I got it, so it's probably been 3 years since I started using aluminum soft haws. For the price I get them for, I won't be going back to steel jaws any time soon.

When I get a job that requires a stronger jaw. I'll make some out of 7075 aluminum. The jaws I buy are made from 6061.

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And that relates to the topic of this thread how??

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.

Thank you all for the replies. I'm sorry if i wasn't clear the way i am measuring is to put a depth gauge in the spindle and then move the travel of the table and move down to Z=0 at each point i want to measure and read the dial gauge. I have done the tram where the dial indicator is in an indacol and swept in a circle when we first got the machine, i chose this other way because i am really concerned with the Z distance right under the spindle when i am cutting.

The ideal situation would be to remove the table and have it ground, but i fear this will be time consuming and we have work backed already, this may be more of a long term solution once we get a second machine.

The reason i called the middle slot of the tormach a "precision" T slot is because they market it that way, it is supposed to be ground and in very good alignment with the x-axis movement. The rear surface does look like a ground surface on my machine, it's just like the whole table is cocked to one side.

And on using vices with out the keys, i do routinely just indicate them in, it doesn't take long. But we switch fixtures and vices daily, sometimes a few times a day, and a lot of our parts are automotive or castings, so if i could set a vice on and know it was within a few thousandths it would be good for a lot of our work. All of the precision stuff of course will be dialed in by sweeping the vice each time it is put on.

I guess two questions i have are is the theory of leveling and tramming the Tosa Tool Plate ok, would something like that work and give good results without much maintenance. The larger table size would be good for fixturing as well. And the second is has anyone else seen something like this with their machine, are most of everyone's machines much better than this?

Shimming the Tosa plate should resolve your problem. while you're at it, you might consider actually mounting the Tosa on risers, to create space underneath it, to facilitate cleaning the screw/dowel holes - Kill two birds with one stone.

I would suggest you contact Tormach, and report what you've found. What you describe seems far outside the normal range of tolerance one would expect from a Tormach. Perhaps they will offer some better resolution.

Regards,
Ray L.

couldn't you just add a sub plate.....face it flat and cut the keys you want....presto !

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Originally Posted by EvolveES

Thank you all for the replies. I'm sorry if i wasn't clear the way i am measuring is to put a depth gauge in the spindle and then move the travel of the table and move down to Z=0 at each point i want to measure and read the dial gauge.?

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Are you moving the Z axis at each test point? If you are why?

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Originally Posted by SCzEngrgGroup

And that relates to the topic of this thread how??

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You wouldn't understand.

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Originally Posted by Steve Seebold

I ALWAYS use soft jaws in my vise. I will indicate the vise straight and then machine a step in the jaws and I get a surface that's parallel to the axis of the machine.

I took the steel jaws out of my vise right after I got it, so it's probably been 3 years since I started using aluminum soft haws. For the price I get them for, I won't be going back to steel jaws any time soon.

When I get a job that requires a stronger jaw. I'll make some out of 7075 aluminum. The jaws I buy are made from 6061.

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I understood what you were saying Steve, great tip.
walt

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Originally Posted by SCzEngrgGroup

And that relates to the topic of this thread how??

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Steve is pointing out how milling the soft jaws parallel to the axis gets rid of any inaccuracy in the "precision t-slot", allowing the vise keys to be used and still achieve good accuracy.

Good tip.

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Originally Posted by Steve Seebold

You wouldn't understand.

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But Steve, I suspect others besides Ray missed your point, so instead of sniping, how about just helping out. Bickering in this forum probably drives away a number of would-be Tormach customers.

If someone didn't understand they could have just nicely asked instead of sniping

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And that relates to the topic of this thread how??

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true? he did help.

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Originally Posted by tmarks11

But Steve, I suspect others besides Ray missed your point, so instead of sniping, how about just helping out. Bickering in this forum probably drives away a number of would-be Tormach customers.

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The bickering was clearly instigated by ray so calling steve on it is utterly ridiculous. how about you keep remarks like this off the forum because you are not helping either.

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Originally Posted by SCzEngrgGroup

Shimming the Tosa plate should resolve your problem. while you're at it, you might consider actually mounting the Tosa on risers, to create space underneath it, to facilitate cleaning the screw/dowel holes - Kill two birds with one stone.

I would suggest you contact Tormach, and report what you've found. What you describe seems far outside the normal range of tolerance one would expect from a Tormach. Perhaps they will offer some better resolution.

Regards,
Ray L.

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If you put your Tosa Table on risers, you'll be giving up some of your Z axis envelope.

Another solution to keep chips from accumulating in the screw holes is to fill them with set screws. I made a plate similar to that out of 2 inch thick aluminum to go on the table of a Haas VF7. The VF7 had a 32 X 84 inch table. I put the screw holes on 2 inch centers, one inch from the back edge and every other row was offset 1 inch.

It took 630 1/2-13 set screws to fill all the holes, but when it was finished, I could clamp anything, anywhere on the table.