Mogliced Sherline backlash report

Tonight I had a chance to measure the backlash on my Mogliced Sherline
mill. I have a Starrett Last Word 15-0-15 indicator, which I held in the
spindle using the 3/32" collet. I'm using CNC Pro, which has fast, slow,
and incremental jog. I set incremental jog to .010"

First I turned the point horizontal and slow jogged the Z down until the
contact point (sphere) touched the table by about .005" for preload, and
zeroed the dial. I switched to incremental jog and jogged down a commanded
.010" The dial then read .010". I jogged up one increment, and the dial
read .001" So the Z backlash is .001" I jogged up and down one increment,
and the dial read .000" (i.e. showing .001" backlash again in the other
direction, canceling the original backlash accumulation.) I repeated this
several times to verify that this was a repeatable reading. So the Z
backlash is .001"

I did the same for Y, getting .001" backlash. On X, the backlash is .0025"

I'm very happy with the .001" Y and Z backlash, and pretty happy with the
.0025" X. I'm assuming that I was more generous with the release spray
than Ron Ginger was, who reported less than a thou backlash on his machine.
CNC Pro has backlash "compensation" so I will enter these numbers in the
program before I start using the mill again.

Once I get some kind of ability to mount the indicator to the gantry's Z
axis, I will do the measurements there. It is scary fast--300ipm rapids
with CNC Pro on my 466MHz Celeron. I was unwilling to go faster, and will
probably "keep" rapids to 100ipm. That machine will get a Sherline head
assembly when I can afford it (i.e. the machines transition from "hobby" to
"earning their keep" :-)

(For Dee and company at Devitt, photos of my Mogliceing are at:

http://photos.groups.yahoo.com/group/cad_cam_edm_dro under "Fun with
Moglice")

Best regards,

Randy

Randy Gordon-Gilmore ,----.___________ ______________ _________________
ProtoTrains // = = === == || == == == = || == == == = == =|
Rio Vista, CA, USA /-O==O------------o==o------------o==o-----------o==o-'
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