Tramming SX2 fixed column milling machine

[bigmini]

Hi folks, it's been a while since I last posted, having not been doing much of interest in the workshop until now.

Yesterday, my annual bonus went toward a Sieg SX2LF Milling machine. I spent yesterday cleaning off all the packing grease,  relubing everything & bolting to the workbench  followed by some test cuts.

These test cuts showed the cutter wasn't cutting evenly (evidence of a tilt), so I put a dial indicator in the quill mounted on it's arm, and checked both ends of the table.

I found a 0.40mm difference from left to right and about a 0.1 mm difference front to rear. This was with all of the axes clamped. This difference is pretty consistent regardless of column height or table position.

I checked the alignment of the spindle with a piece of hex bar in a drill chuck and it seems OK. I checked the difference in level from front  to rear and that seems OK too. I tried loosening the holding down bolts in case the benchtop was warping the base, no joy there either.

It would be simple to fix it, except that this model Sieg does not have the tilting column.  The column is held down by four mounting bolts. I've done a search procedures but they all refer to the X2 type with the tilting column.

Should I remove the column and try shimming one side? or is there an adjustment I might have missed. The user manual is no help at all. I suspect Google translate was one of the authors.

[Brass_Machine]

I believe you have to shim it.

I have the solid column kit (to convert my X2) and as far as I can see, there are no adjustments anywhere. Most non tilting mills you have to shim the column (iirc).

Eric

[bigmini]

It took 3 goes, some alfoil, and some basic trigonometry, but I finally got it down to less than 0.01mm in all directions. That's the limit of reading of my dial gauge and the minimum increment I can make at the column base. (The alfoil is exactly 0.01mm thick).
 

I took photos of the whole process and I will prepare a step by step if anyone's interested.

The only misgiving I have is that the alfoil may creep over time and squeeze out. Time will tell. In the meantime I've written down the amount of correction  used at each bolt, so it would be just a matter of reproducing that using brass shim if necessary.

[John Rudd]

The only misgiving I have is that the alfoil may creep over time and squeeze out. Time will tell. In the meantime I've written down the amount of correction  used at each bolt, so it would be just a matter of reproducing that using brass shim if necessary.

Which is why you would ordinarily use steel shim....Couldn't you obtain some steel shim of the requisite thickness?

[bigmini]

Not on a Sunday, no.

[Pete.]

Sure you can, a couple of cheap sets of feeler gauges is all you need.

[Brass_Machine]

I took photos of the whole process and I will prepare a step by step if anyone's interested.

Yes Please! 

[Jonfb64]

Me too as i have the same mill and it needs tramming. 

[bigmini]

Sure you can, a couple of cheap sets of feeler gauges is all you need.

Y'know, I never thought of that. 

Could have saved a lot of time cutting and punching bits of alfoil. Now that it's done I'll see how I go. If it behaves, I'll leave it and post my photos, but if it goes loose over time, I'll pull apart my feeler gauge and post photos of that.

The trig is simple and speeds things up by calculating first.

[Fredbare]

I would certainly be interested in this.

John

[andyf]

I'm trigonometrically challenged. My round column mill's head can be angled from the vertical, so getting the X axis right is just a matter of patiently tapping with a soft hammer until the DTI doesn't move. But on the Y axis, shims were needed, and I used the method set out here which directly measures the thickness of the required shims. Skip to half-way down page 6.
http://rick.sparber.org/TM.pdf

In my case, having already fixed the X axis, I only need two marks for the Y, one near the front of the table and one near the back, the distance between them being equal to that between two of the four bolts supporting the column, being a front bolt and a rear one. This showed that the head was nodding forward and 0.05mm/2 thou of shim was needed. I used alumimium foil. This may well creep, but the mill is an old round column one, and the column may not be dead straight. I trammed it with the head at  working height for an exacting job, but if the column is not dead straight, it will not remain in tram when a taller or shorter workpiece requires the head to be at a different height, so the exercise may have to be repeated before too long.

Andy