Runout on LMS SX2.7 mill

[salindroth]

I like LMS products and have enjoyed using the SX2.7 mill, but the spindle runout is miserable: 0.0045" at 5" from the spindle (i.e., about where a drill bit would wind up). Even then I've been able to drill reasonably located holes. The real problem is end milling -- I get massive "ripples" on the work piece surface, which is not surprising given the runout.

Is there anything to be done about this? When I had an S2 mill, it was easy to replace the spindle bearings, which resulted in greatly improved runout. The SX2.7 is a lot heavier, though. I would need a hoist or crane of some kind to lift the head off the column. I'd welcome advice along with any "war stories" you have after dealing with a problem like this. Thanks.

 

[higgite]

Have you measured actual spindle runout, that is, the runout on the inside taper of the spindle with no collet installed? What you’re seeing at 5” from the spindle could be collet runout. Have you measured runout with different collets? What exactly are you mounting in the collet to measure the runout at 5” from the spindle?

FWIW, my LMS 5500 (Sieg SX2.7) spindle taper had .00035” TIR last time I checked it. I forget how much it was when new, a couple of tenths as I recall, but I’ve slept since then so don’t hold me to that.

Tom

 

[salindroth]

Thanks, Tom. Runout at the spindle is 0.0005". I'll try different collets. Maybe end milling with a smaller cutting tool with a slow feed rate will make the ripples more fine-grained.

Scott

 

[higgite]

Thanks, Tom. Runout at the spindle is 0.0005".

Oops! I missed a decimal place in my previous post. Runout on mine was .00035", not .0035". I've corrected it now.

Tom

 

[9t8z28]

I would say that is pretty darn good for this machine.

Oops! I missed a decimal place in my previous post. Runout on mine was .00035", not .0035". I've corrected it now.

Tom