perpendicularity problem of PCNC 1100?

[chennan]

Dear all,
My lab recently bought a PCNC 1100 series 3 with a deluxe stand. I was working on assembling them and I found that the perpendicularity of the spindle to the table surface is off by about 0.13/200 in x axis. While this is much more than the tolerance in the certificate of inspection(0.04/200), I called Tormach and they said this may be caused by not putting shims between stand and mill since "the stand and mill are not designed as a matched pair". Has any of you who also bought PCNC 1100 encountered this problem? Or fix it by inserting shims between stand and mill?
Thanks a lot.
Chennan

[TXFred]

Here you go.

http://www.youtube.com/watch?v=lle-k_ccFAA]Tormach PCNC 1100 - Adjusting Mill Tram by shimming the base. Ch. 12 - YouTube

[chennan]

Here you go.

Thank you, I will try this method. In this video it is about 2 mills difference in maybe 15" range. But my machine is of about 6 mills height difference in 10.5" range. Do you think it is normal?

[Steve Seebold]

One thing I see that is done wrong in the video is he is grabbing the indicator to swing it. NEVER grab the indicator to rotate it, ALWAYS rotate the indicator by turning the spindle.

If you rotate by holding the indicator, you stand a goog chance of getting a false reading because you can move the indicator.

JMO

Steve

[philbur]

There are a couple of other things wrong with the video.

1) There a number of reasons why the spindle may not tram. A twisted bed when bolted down is only one of them.
2) The table centre of gravity is all the way to the left so if he has a loose gib somewhere the table will lean and the spindle will not tram square.
3) Possibly the best solution is not to bolt the bed to firmly to the table in the first place.

Twisting the bed in an attempt to correct some other error just gets you deeper into the long grass.

The more correct, all though not complete sequence, before you bolt the mill firmly to the stand is.

1) Shim the base on the stand under all four corners so there is no free play/wobble.
2) Check the column is square to the table in both axis. Correct if necessary.
3) Check the spindle is square to the column in both axis. Correct if necessary
4) Check the spindle sweeps the table within the specified tolerance. If it doesn't recheck 2) and 3)
5) Bolt the base to the table then repeat 4). Adjust shims as necessary.

It's not the whole nine yards but its a lot better than just sweeping the table and then bending the bed to suit!

Phil

[David Bord]

Yes, I believe this is common. The stand is not rigid, so if your floor isnt level, that can transfer to the pads of the mill. I made a little jack screw to adjust mine and was able to get nearly perfect. If I remember, mine was off quite a bit before adjusting. I thnk it was my un-even floor and the early stands where were not a nice as the new ones.

David

[Sp-4renegade]

Thank you for reminding me, I forgot to do it. I just did trammed it. Mine Series 3 was off .008 in X only. Little shim and good to go. Just to loosen the bolts I could see a few thou diff.

[chennan]

Thanks to all.
I lift one corner of the mill up using the method in the video. And insert 1 metal film and 1 plastic film. Finally I got 0.01/200 in x axis and 0.016/200 in y axis which is within the tolerance showed in the certification of inspection(0.04/200). I think there is potential to in further increase the perpendicularity, but deformation of the table under gravity should be considered and make it complex.
Thanks again to all who post in this topic.