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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 187 - Sat 12/19/98
2. NEW: Need Source for Canvas Belts
3. NEW: Turquoise Identification
4. RE: Lapidary Equipment Plans (Sphere Machine)
5. RE: Leather for Polishing
6. RE: Leather for Polishing
7. RE: Leather for Polishing
8. FS: Back Issues of All Rock Magazines


Subject: LapDigest News for Issue No. 187 - Sat 12/19/98

There were three queries in the last issue which were not
answered; They are restated here and I hope they will get

--- Lortone Portable Combination Unit Speeds. What do the
numbers 1,2,3,4, etc mean on the portable combination unit?

--- What is Pietra Dura? and how do you polish it?

--- Polishing Feldspar. On a vibratory lap, last feldspar
block got a large dirty gray blotch from the fine grit. Is
it porous? How do I keep this from happening on Amazonite?

>From the mail received, I guess the header problem has been

And so we are now on a slow smooth slide to Christmas and
New Years. You guys have a great holiday season, and may
you have a peaceful, healthy, safe and bountiful 1998!! Hug
your kids, kiss your mates and ... have fun!!!


Subject: NEW: Need Source for Canvas Belts

I am looking for a source for 3" wide canvas belts to fit
an 8" expandable drum. To be used with tin oxide or cerium
oxide for polishing. Can anyone help?



Subject: NEW: Turquoise Identification

I recently purchased some stabilized turquoise at a show
and forgot to write down the name of the material. It
is from the Kingman mine and it is emerald green with
the golden brown matrix found in other Kingman turquoise.

Can anyone help me with the name?

Randy Aue

Subject: RE: Lapidary Equipment Plans (Sphere Machine)

<<If some one out there has plans on how to build a sphere
machine would they please share on the web-site.>>

A sphere cutter is easy to make if you have a spindle such
as on a flat lap.

Pick up a (2 inch) pipe plug, the kind with a square bolt
head on the end, at your hardware store. Drill and tap thru
the center of the square bolt head so it will fit on your
(vertical preferred) spindle. Also pick up a brass 90
degree elbow of about the same size (its easier to hold
than a straight pipe).

Cut a cube of rock and then trim off all the corners with
your saw. Use a coarse grinding wheel to smooth it more
towards a sphere. Put your lumpy ball on the plug (that is
on the spindle, bolt end down and round edge, which should
be cup shaped, up) and hold it down with one end of the
brass elbow. The two pipe ends should make a 15 to 30 degree
angle - you'll quickly find the right angle, and rock it a
bit as it works. I find a lower speed works better.

Turn it on and start applying coarse loose carbo (tumbling
grit) in a water slurry (you can pour thru the elbow) and
wear goggles to protect from splash. Turn it off before
removing the top pipe or the ball may fly (or pick up the
ball off the rotating bottom pipe end, but be careful).

Work thru the grits once it is round, cleaning the pipe and
plug well between them (the pipes can imbed grit, so a steel
brush helps).

Glue on felt or leather circles to polish, or put the ball
in your tumbler with a handful of garnets the size of peas
and pre-polish/polish it that way. About $10.00, including
the tap to put the threads in the hole and a bit to drill
it, and maybe an hour of time. Works great.

Kreigh Tomaszewski

Subject: RE: Leather for Polishing


I usually use something closer to 2mm, but 1mm should do OK.
Except in special cases (like the recent discussion about
jade) you aren't going to be putting a lot of pressure on
the stone. You could also cut a felt pad for under the
leather or use a couple of layers.

I've used both sides of leather; different stones work
better with different surfaces. Quartz, opal and spectrolite
seem to do better with a slight nap. Probably because it
holds the water and cerium oxide better.

I've never had stones pick up any color from a lap. Usually
it's the other way around: green stains from malachite,
rusty red from silkstone or tigereye, etc.


Subject: RE: Leather for Polishing

>From what I understand leather laps need to be quite a bit
thicker -- I have stitched thin leather to a plastic
placemat (like you put under your plate at the dinner table)
to compensate (beware you can throw the timing of your
sewing machine off -- operate the machine by hand).

Still I'm not happy with the leather as its not slick and
grabs the stone making it a very bumpy ride. This is even
adding oil for lubrication. Does any one know how to make it
work more smoothly?

Susan Herrmann

Subject: RE: Leather for Polishing

Mmm, I can almost smell and feel that leather. As light as
it is, it seems to me that you would have to adhere it to a
backing, maybe cork, maybe a dense sponge rubber. You could
always be selective in colors, choose a dark green for
jades, a reddish one for jaspers.

However, if I had such beautiful leathers, I would be
inclined to try them as backs for beaded bezels, or perhaps
as little presentation bags for nice cabochons whip stitched
together with a seed bead or two on each stitch.

Rose McArthur

Subject: FS: Back Issues of All Rock Magazines

I have numerous back issues of almost all rock mags these
are all extras after filling my collection if there is a
mag you are looking for let me know the mag and the issue;
I'll get back to you with availability and cost. I go back
to almost first issue on most mags and there is some I'm
still looking for, like Vol 1 No 1 of Lap Journal.

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