Microwave Guide Cavities - Photo courtesy of Dave Halverson
Received the MYTMILL software and it installed OK. Nice package, works
good on a "real" PC. Thanks.
Please find attached six (6) jpg's of the mill I purchased from you.
Unfortunately my lighting was quite poor as both 500W halogens went out
on me within a few minutes of each other. Will get them replaced
tomorrow and redo the photos under proper lights.
BTW, the rolling work carts cost about $80 - $130 at Sears. Note the
"precise" fit as shown in ML1_02.jpg.
Things I would still like to do:
- find a couple of molded way covers (baffle) for the Y axis
lead screw (trying to get a local manufacturers price down).
- develop a rigid tapping head (replace the spindle motor with a stepper)
and beg someone to add the G code :o)
{hand tapping several dozen 2-56 or 4-40's for a
uWave cavity cover is always quite exciting!}
- add a cutting fluid pump (note the lip on the work table is ideal
for this and the top drawer converts to the reservoir).
I've dropped the idea of creating a "closed loop" control system since
the current "open loop" using steppers works so well. Other than actually
testing a stall condition, I have yet to loose a step or stall the mill.
Should a step or two ever be lost and quickly noticed, the software will
show a different X, Y or Z value than the Sherline readout, so it may be
possible to figure out where you are actually at, back up the program,
and save the piece.
Generally, I run about 4/5ths the calculated "feeds and speeds" for
the particular material, observe the material thermal properties and account
for cutter usage (dulling). Also, for thin walls I rough cut using Anchorlube
G-771 then let the material cool; and finish cut using a sharp cutter,
go very slow and flood the piece with TapMagic cutting fluid (very smelly
but it works great).
The Sherline backlash adjustments are set quite tight, with the electronic
offsets set to the nearest step increment(0.000125") as measured using
a precision dial indicator. The backlash is checked often following
a backlash nut adjustment but tend to stabilize after only a few hours
of operation. I also make it a habit to check backlash as part of
every setup.
A small, high volume, squirrel cage fan (off an RF transmitter heat
sink) is positioned to cool both the spindle motor and the bed. It
tends to keep the mill cool and helps, to some extent, direct the chips
toward a super shop vac that I often leave running. For the most
part a small acid brush is used to remove chips from the piece or judicious
use of compressed air is sometimes used if careful attention is paid in
not forcing chips into the cutter - small acid brush is better IMHO.
This mill has performed extremely well over the past two years, or
so, and has really "earned it's keep." However, I would advise anyone
considering a new purchase to go with a metric machine if at all possible
since metric offers more steps per unit length than does an inch machine.
This translates to increased precision.
Thanks again for your prompt assistance. I hope the words and
pictures provide some insight.
Best regards,
Dave Halverson
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