Tram issue: Need 40 thousands (1mm) of shims to get proper tram.

[cordvision]

I'm having a bunch of issues with my Tormach after moving it to a new location. Can't quite pinpoint what is the root cause, so I thought I just post it here.

I set up the Tormach 1100 Series 3 in a new location. I have an old concrete shop floor that is not completely flat but also not absolutely terrible. I noticed that a z-probe would
move a lot when I was pulling a little bit on the motor housing, so I checked the z-axis gib.
Turns out that the top z-axis gib screw was completely loose (I could turn it easily with my fingers). I therefore adjusted the z-axis gib using lost motion to judge proper "tightness".

After that procedure, I noticed that tram was off by a lot (.012") in the x axis. It was dead on before adjusting the z-gib.
It took .04" (1mm) of shims under the front left mill pad to get tram back on. I concluded that something must be really wrong and I must be twisting the mill. I called tormach, but they told me that this is not
unusual, especially if I have an uneven floor. I was not really satisfied with that, as I felt that there must be some other issue.

I spent a good amount of time to get the mill stand as level as possible by adjusting its feet. However, this didn't change anything regarding to tram. It seams that the adjustment of the stand feet has no measurable influence on tram at all. I can use a car jack on one corner of the mill stand and jack it up to simulate a super uneven floor, but tram stays exactly the same.

I then kept experimenting with lifting different corners of the mill base, lifting each corner individually, or at one point I lifted on the left side in the middle so the mill was only standing on the right two feet and the left lifting point. No matter what I did, I always came back to needing .04" of shims on the left front leg as the best option to get tram on.

Any ideas what might be going on?

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[popspipes]

I tried shimming the front foot to tram the Z to the X axis, all it did was twist the base, I finally pulled the dowel pins from the head to the slideway?? and moved the head until it aligned with the X axis and retightened the head mounting bolts, this fixed it. the alignment dowels were off just a bit and are still loose, but the mill is in tram in the z-x axis.

The front feet on mine have equal pressure on them which I adjusted with shims before adjusting the Z-X tram.

Shimming the front foot would get the mill in ZX tram but when the Y was moved it would be off again, which led me to believe that the base was twisted slightly.

[philbur]

0.012" is a lot for a new machine, at what radius are you measuring? I would look very carefully at everything before trying to twist anything by shimming. Have you tried supporting the mill base on three points only and then measuring, as has been discussed in a previously thread.

Have you compared the tram of the spindle with the vertical motion of the head. In other words is the column leaning or is it just the head leaning.

The head has 2 dowel pins that maintain position of the head relative to the head carriage. If you pull the pins you can realign the head in the x axis by slacking off the 6 head bolts. You can also shim under the column to realign it. However if it were me I would want to be 250% positive I new exactly were the problem was before doing either of these, otherwise you may compound the problem or introduce a new one.

Phil

[cordvision]

The radius was about 4-5 inches (little less than 10 inch diameter). Being 0.012" out of tram without shims seams really extreme since it should be possible to get it within 0.0005" (60x less).

I tried to support the base only on 3 points by putting a support between the left two pads. This meant that the mill was only sitting on the right two pads and the support block between the left two pads.

How would you compare the tram of the spindle to the vertical motion of the head?

[rowbare]

Any ideas what might be going on?

"Everything is made of rubber" (Forrest Addy on HSM)

The mill base is much more rigid than the stand. The part of the stand that has the mounting pads is rigid enough to influence the base (even though it flexes more than the base), the rest of the stand, not so much.

On my early Series 1 even how tightly the mounting bolts are torqued has an effect.The pads on the older stands weren't machined after welding as they are now.

In any case, the effect you are seeing is not unusual though the magnitude seems a bit on the high side.

bob

[popspipes]

The radius was about 4-5 inches (little less than 10 inch diameter). Being 0.012" out of tram without shims seams really extreme since it should be possible to get it within 0.0005" (60x less).

I tried to support the base only on 3 points by putting a support between the left two pads. This meant that the mill was only sitting on the right two pads and the support block between the left two pads.

How would you compare the tram of the spindle to the vertical motion of the head?

I supported mine on the two back pads and the center point was located between the front two pads. I then shimmed the front two pads for equal pressure on them.

[cordvision]

I tried that too, but I would have to take the chip pan off to get access. Were you able to do it without taking it off?


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[eisa]

plz dxf

[popspipes]

I tried that too, but I would have to take the chip pan off to get access. Were you able to do it without taking it off?


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Yes they are readily accessible, now the colum screws thats another story!

I left the two back screws tight, loosened the front mounting screws and set them for equal pressure with shims. I am tallking about the mounting screws that mount the machine to the machine stand, not the colum screws.

[cordvision]

How exactly did you set them for equal pressure? I have a little block of aluminum with a tapped hole in it and a hex bolt. I use it to lift up the mill for shimming. My problem was that I didn't have enough space to use a wrench on the hex bolt when I placed this little jig in between the front pads. The chip pan got in the way.


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[popspipes]

I think I did this before the sheetmetal, youre right it does pose a problem.