Milling machine soft foot!!

[ChipsAhoy]

Received a new Grizzly G0755, and one of the many steps in setting it up was tramming it. That is, to check spindle is perpendicular to the table. It was not. I'll not go into that, it has been covered a couple of time in other threads. BUT, what I did find was that my column had a "Soft Foot". In tightening down the column after shimming, the readings were not consistent.
I have a square column with four bolts in a rectangle, after putting in what should have been the right thickness of shims on the front two bolts, I checked to see how close It came out. WOW, either I calculated wrong, measured my shims wrong or I was corrupting my dial indicator. An hour later and after many many shim changes I discovered a soft foot.
Put the dial indicator in a fixed spot, loosen and re-tighten the bolts in a different sequence but to the same torque. Readings all over the place, well mine were. It seemed like the column was rocking, and It was. Lucky for me I found metal chips, from manufacturing and assembly I assume, But could have been a warped bottom, bad machining on the base (which I had figured as most likely), or crap left on the surface!!

tried but I can't put in pic's, I guess I reached my limit, but the description should do anyways.

Scotty

 

[tertiaryjim]

Try mounting an indicator in the spindle and zeroing to the table.
Then loosen a column bolt and record the deflection noting positive and negative.
Tighten the bolt before moving to the next one.
This gives a map to determine the best shim change from.
You might post your results with dimensions of the bolt pattern and distance to the indication point.
To get the column as close as possible, you will need shims that are in 1.5 mill increments.
IE: 0.0015", 0.0025" or 0.0035"
I have extra in 1.5 and 2.5 mill thicknesses if you need some small pieces.
Send me your mailing address if you need em.

It would be a lot more work but you might also consider scraping the mounting faces to get them in.
This would provide the best rigidity for the column.
Jim

 

[Bill Gruby]

Have you notified Grizzly of the problem yet? At this point it should be your next step.

"Billy G"

 

[ChipsAhoy]

I've not notified Grizzly yet, the machine has other 'issues' that they will fix as we go along.
But it appears to be a nice machine... I like it.
Tramming is all done. Along the "Y" I'm only off .0015 in 10".

Scotty

 

[tertiaryjim]

You might try raising the head and checking the tram again to see if the column dovetail is true.
0.0015" in ten inches would be a lot on a good full sized machine and while I can shim my china cheapo to read about 0.0005 in twelve inches
it's gonna read way off when I move the head up or down.
Knowing how the machine is going to react to moves can save you some oop's moments!
Hope you were able to fix the soft foot problem.