Fun with Moglice

This weekend I cast Moglice nuts on my Sherline mill leadscrews and my
Sherline lathe cross slide screw (due to the way I cast the nuts, I
couldn't do the lathe saddle nut at the same time, unfortunately...) I'm
extremely happy with the results.

The Sherline mill column has a brass nut which kind of floats relative to
the head. (The lathe saddle is the same.) The nut is held by a single
10-32 screw, and perched on the points of two setscrews that determine its
alignment relative to the head. For the Moglice retrofit, I was not
satisfied with this arrangement. Since the Moglice will have next to zero
clearance, I wanted a solidly- and repeatably-mounted nut.

I measured the distance between the nut mounting surfaces (lateral and
fore-and-aft) and the leadscrew centerline. Then I silver-soldered brass
shim on both mounting surfaces to bring the nut center in line with the
leadscrew center, when it was bolted up tight to the head.

I drilled out the nut to leave 1/16" wall, and roughened up the I.D. with
a small slotting cutter in my Dremel tool. I turned up centering rings
from some Teflon rod to hold the leadscrew tightly and accurately centered
in the bore in the column (and thus parallel to the head travel) while I
cast the Moglice.

For the mill and lathe saddles, I milled out pockets for the Moglice. I
used Ron Ginger's idea of using the original brass nuts and
"anti-backlash" nuts to contain the Moglice from running out the ends of
the bore. The leadscrews run in a clearance hole in the saddle, which is
step-drilled to accept the nut, which is just a little cylinder of brass
tapped for the leadscrew. I extended the enlarged bore to place the brass
nut past the milled-out bore, and filed the flanges off the
"anti-backlash" nuts to give the second containment nut. On the lathe, I
used a 1/4-20 brass thread insert and turned it to the right O.D.

Since the Moglice is described as "fluid", I was imagining how it would
flow out any little gap, but was unsatisfied with the idea of using putty
in the threads to seal. (By the way, I made the mill saddle recess a
little too big, and broke through into the V-way area behind where the gib
sits-I did plug that with plumber's putty…) After much thinking during my
commute drive, I hit on the idea of using Teflon pipe tape to wind on the
threads behind the containment nuts. That worked very well, and no
Moglice leaked out at all.

The Moglice release spray is wax dissolved in naptha and some other
solvents. After degreasing the leadscrews with lacquer thinner and
pre-placing the backup nuts, I sprayed two good coats (5-6 seconds per
leadscrew) of the wax and let the screws sit overnight. The spray goes on
translucent, but dries to a white waxy appearance.

I assembled the leadscrews in the saddle bores, and placed the mill head
and leadscrew in place on the column. I wound Teflon tape on the column
leadscrew in place, and lowered the bored-out nut onto the mass of Teflon.
This was enough to seal it. I did all this prep work on Saturday. On
Sunday afternoon, I cast the Moglice.

The filled component of the Moglice was the consistency of un-homgenized
peanut butter-all the solids had settled to the bottom. I pre-mixed it
with a Popsicle/craft stick, scraping the sides and bottom of the
container well. I then discarded the stick, added the other component and
mixed well with a second stick. This way, there would be less of a chance
for unmixed resin. The mixed Moglice was about the consistency of honey.

I filled the recesses in the mill and lathe saddles and then turned to the
column nut. The clearance was so small that I could only apply a fraction
of a cubic centimeter (using a small disposable plastic syringe) at a
time, and then vibrated it down into the gap by pressing the platen of a
palm sander (with the sandpaper removed!) against the nut. I repeated
this 4 or 5 times, until the nut seemed full. I went back and vibrated
the saddles too.

Monday night when I returned from work, I freed the leadscrews. I had
read of the difficulties of breaking the leadscrews free initially, and
was prepared to use a lot of force. I wrapped layers of brass shim around
the leadscrew, and gripped it with a Vise-Grip. To my surprise, the
leadscrew broke free easily with relatively little torque (probably not
enough to twist the head off a 4-40 screw…) and, after I removed the
Teflon tape, the leadscrews all turned freely by hand.

I probably was more generous with the release spray than others have been,
but I can't feel any play at all by hand. I'm really anticipating
reassembling the mill, tramming it in, and measuring the backlash
directly. But I have a feeling that it will be well small enough in any
case! :-)

For the lathe, I could not cast the saddle nut at the same time, because
it needs to be solidly bolted to the saddle, and the whole assembly tipped
up on end. This conflicted with casting the cross slide nut, so I'll need
to buy a second batch of Moglice to do the one nut (well less than a cubic
centimeter…) In all, I used possibly a third of the Moglice. The rest,
unfortunately, is a hardened mass in the container. If anyone in the area
is planning to Moglice anything, let me know and we can share the next
batch (as well as the spray release, of which I used a miniscule amount!)

The Moglice I used is the 1000 Fluid, which contains Teflon. I'm really
looking forward to using the "near-zero-backlash" Sherlines!

Photos with captions are in a folder named "Fun with Moglice" in the
photos area of the cad_cam_edm_dro Yahoo group.

Best regards,

Randy

Randy Gordon-Gilmore ,----.___________ ______________ _________________
ProtoTrains // = = === == || == == == = || == == == = == =|
Rio Vista, CA, USA /-O==O------------o==o------------o==o-----------o==o-'
zephyrus@... http://www.prototrains.com