On 3/15/2018 10:37 AM, rangerssuck wrote:
As you may remember, I've been making prototype printed circuits on
my Taig micro mill. I was pretty well stuck, not being able to get
traces small enough. It didn't seem to matter much what my z depth was,
the conical bit wouldn't cut a line that was anywhere near as narrow as
its 0.1mm tip.

Then one day, it dawned on me that that the head was vibrating like a
sonofabitch. I mounted a dial indicator on the bed and positioned the
plunger on the head. There was ± .003" of vibration! pretty much a
killer when trying to mill lines less than 0.008" wide.

I have since replaced the whole headstock with a 1.5KW 400Hz spindle
motor. It runs up to 24,000 rpm and there's no detectable vibration.
This is great. Of course, now that that problem is fixed, it made others
more visible. I noticed that lines in the +Y direction were a different
width than those in -Y. This turned out to be loose gibs, so I took
apart the whole XY mechanism, tightened the nuts to remove all but
0.0005" of backlash in X&Y which I had previously compensated for in
mach3, and adjusted the gibs properly.

All I can say is that I wish I had taken the time to do these things
from the get-go. What a difference. Next (after I get some work out of
the way), I'll do the same with the Z axis.



Hmmmm... I think somebody here might have suggested the 24K spindle on
the Taig. Did you use Paul Heinreichs spindle mounts?

I can tell you from experience its better to adjust out backlash to the
best of your ability and ignore the Mach 3 backlash compensation. I've
watched it steadily work a profile cut across the part as it gets
confused before.

My experience showed me a Taig mill could be adjust reliably to under
..001 backlash and run ok, but it would limit the ability to rapid
without losing steps. With it loosened up to about .003 backlash
overall mine would cut upto about 60IPM and rapid up to 80ipm. Of
course that is also dependent on your motors and controller. Whether or
not that is "good enough" depends on the type of job you are doing and
how you approach the job.