Web Site: http://www.lapidarydigest.com

This list digest contains the following message subjects:

1. LapDigest News for Issue No. 188 - Wed 12/23/98
2. NEW: Slab Saw Blade Reducer Insert
3. New: Handling Small Stones?
4. Re: What is Pietre Dure?
5. Re: What is Pietre Dure?
6. RE: Polishing Feldspar
7. RE: Need Source for Canvas Belts
8. RE: Need Source for Canvas Belts
9. Re: Leather for polishing
10. Re: Leather for polishing
11. RE: Polishing Spheres
12. Bio: Dee Purkeypile
13. BIO: Trevor Flory


Subject: LapDigest News for Issue No. 188 - Wed 12/23/98

I hope each of you have a wonderful holiday. Please take
care of yourselves and stay safe. Hug your family and wish
them a Merry Christmas from me!

I might not publish the Digest between Christmas and New
Years -- may go to Charleston and spend Christmas with some
of our family! (depending on the weather!!) Normally, the
next issue would be published on Saturday; if you don't get
one then, you'll know I am gone!

I want to wish a very, very


to you, one and all!!!


Subject: NEW: Slab Saw Blade Reducer Insert

I am 44 and a fairly new comer to lapidary. I have been
cutting rough and making cabochons for three years but
still have a lot to learn. I have never had to repair
(or attempt to repair) any of my equipment up until now
and need some advice.

I recently purchased an older 18 " Lortone slab saw. The
blade on the saw was worn out, and slightly dished so I
decided to purchase a new one. I purchased an 18"
Criterion blade from MK Diamond but it doesn't fit onto
the arbor as tight as the old blade. This makes the blade
"pound" a little ( I haven't cut rock with it yet). The
hole in the blade has been reduced from 1" to 3/4. The
arbor on my saw is 3/4. Could it be the reducer? Should
I try and purchase a new one from a local hardware
distributor? Should I remove the arbor to see if it is
square? If so, how do I check it? I have an exploded view
of the saw.

Lots of questions.

Thanks, and Happy Holidays to all.


Subject: New: Handling Small Stones?

I've been working small pieces of opal and sapphire,
lately, and I'm struggling with how you hold these. I'm
using my CabMate for the work.

I started using nails and superglue for dopping, but for
some pieces even the standard nails are big and I need to
use finishing nails. Unfortunately, there isn't much
bonding area and they don't seem to hold securely. Plus
the nails are hard for me to hold.

What do you folks use for small stones?

Bob Lombardi W4ATM in Melbourne, FL
blombard@iu.net or blombard@freenet.fsu.edu
Bicycling, telescope making, optics, astronomy, Radio
Design, piano, SW and ham radio

Subject: Re: What is Pietre Dure?

Pietre Dure, literally "Hard Stone", is an intarsia mosaic
made entirely, as the name implies, from hard colored stones
like jasper and agate, as opposed to those made from
marbles, which are considerably softer; although the hard
colored stones was often inlaid in black marble for

The art of Pietre Dure flourished in 19th century Italy,
being used primarily for tabletops, as well as for other
smaller art objects. The technique involves choosing exactly
the right piece of stone to achieve the effect desired, so
that the color shadings in each piece of stone approximate
those of a pictorial element such as a leaf or flower
petal, and the piece as a whole resembles a painting.

The pieces of stone are flat on the front, and may be
polished in any way that produces good flat polished
surfaces, such as a vibrating lap. Generally the stones were
prepolished and then ground to shape, with each stone
supposed to fit as tightly as possible against its
neighbors. This, as may be imagined, becomes quite a
technical feat to accomplish well, and requires a lot of
skill, as well as time. There is still a Pietre Dure Museum
in Florence, which I was fortunate enough to visit,
celebrating the vanished glories of this craft. The modern
Italian items offered to tourists as Pietre Dure are not up
to the old standard, although I have seen some good work
coming out of Russia recently.

Andrew Werby
United Artworks
Sculpture, Jewelry, and Other Art Stuff
(Hale's note: The museum Andrew talks about has a web site
at http://www.vps.it/propart/opd_e.htm. My concern was the
spelling; the museum spells it 'Pietre Dure', and so I have
changed all the words to that spelling. There are 351 web
pages with those words which Alta Vista found. One of them
is at www.texnet.it/artprovider/mosaico.html, and has great
pictures of tabletops and other examples. hale)

Subject: Re: What is Pietre Dure?

Check out the site: <http://inlay.com/stone_inlay/>
I believe this answers the question "What is Pietre Dure?"

>From the web site: There is a book that is currently out
of print, entitled Pietre Dure by Anna Maria Giusti
[ISBN 0 85667 405 2][LC 91-060247]; PUBLISHED BY Philip
Wilson Publishers Ltd in 1992 in London.

On page 297 it says,

"pietre dure, means literally "hard stones". In everyday
and artistic terminology, the term is used to mean semi
precious stones in general. More exactly, pietre dure are
siliceous minerals, rated between 6 & 7 on the Mohs scale."

Does this description help with polishing, assuming the
piece in question was made with siliceous minerals?

I hope this helps. I am a beginner at lapidary, but I can
find my way around the "net".

Carol Cimolino

Subject: RE: Polishing Feldspar

Feldspars aren't necessarily porous, but the crystal
structure develops along flat planes. Given that and the
fact that feldspars don't have much tenacity (the crystals
tend to break away fairly easily), I think your problem is
that a section of crystal pulled away during the rougher
grind and the finer grit worked it's way under.

I've come across this when tumbling spectrolite. The stone
will look solid, but if I see a suspicious looking crack,
I can usually pry it apart with my fingers. I would suggest
slicing or grinding (or pulling?) off that end of the stone
and re-lap it. I'm no expert on flat lapping, but is there
a way to reduce the vibration on your machine? Or perhaps
cushioning the stone somehow? Maybe even so far as cutting
a piece of felt (like for polishing) and using a different
piece of felt for each grind. Maybe then it won't try to
vibrate itself apart.


Subject: RE: Need Source for Canvas Belts

((I am looking for a source for 3" wide canvas belts to fit
an 8" expandable drum.))

Suggest you contact Ed Deckert at EDECKERT@PIPELINE.COM. I
don't know if he stocks them, but he can get them. He is
our club hardware source.

Mark Case
Randleman, NC

Subject: RE: Need Source for Canvas Belts

Karen, any Crystalite dealer will have them or be able to
get them for you. If you don't have a local dealer, contact
me off line.


Subject: Re: Leather for polishing

Regarding the use of leather for polishing:

I have made several polishing laps using new and used
leather. I used to make leather purses and wallets and
belts, so Tandy Leather Supply was a good source for rough
materials for me. I have used Chrome dyed (yellowish)
cowhide (about 1/8" to 1/4" thick), and also English
Calfskin (thin, and very supple), and black split cowhide.
All of these were adhered using Weldwood contact cement to
Crystallite Flexlaps, or homemade 1/4" tempered Masonite
discs with thin carpet padding.

The results are as follows: The chrome dyed cowhide I've
used, I've tried both the suede side and smooth side out,
and the yellow tends to run out, and stained porous stones,
such as low-grade turquoise. Also the suede tended to come
off for a prolonged period, making a general mess. The black
dyed split cowhide also made a staining, but with a lower
nap suede side, it shed much less, and gave a great shine
to Mexican onyx (calcite variety).

My best success has been from the English calfskin. I've
used this wheel for everything from opals to quartz family
stones (jaspers, agates, glass, etc.) with the suede side
out. I make a slurry/paste of cerium oxide (faceting grade)
and paint the wheel while it is laying flat, and let it air
dry. Then when I use it I use a mist bottle to keep the
surface tension down, and cool the stone. (P.S. - I use
this on my Crystallite RingLeader.) The ability to find a
surface speed appropriate for the particular stone allows
me to run this wheel very dry, and prevent the slinging of
the compound off of it.

I also store all of my laps (Flexlaps, and faceting laps)
in zip lock storage bags, labeled for the grit size, or
polishing compound, and I always put the wheels back in the
bag the way they came out. This helps to prevent the
airborne dust contamination of the surface, as well as the
aluminum oxide (corundum?) contamination from the backs of
the faceting wheels. Cleanliness is next to Godliness, and
really close to good polishing.

Mark Greenbaum
M.G. Designs - The best in Custom Handmade Jewelry,
and Gemstones.

Subject: Re: Leather for polishing

When using leather as a polishing material, for stones, etc,
it is much easier to use 9-10 oz leather about 1/4 in. thick
as it will not wrinkle, is easily fastened to a stiff
backing such as a flat metal disc with leather glue which is
water proof. This prevents a wrinkle from forming which
could cause a scratch on your stone, but is porous enough to
hold your polishing agent well.

Lila Trudel

Subject: RE: Polishing Spheres

It has been my experience in making spheres to pre-form them
as near as possible to a round ball, cut all edges off with
your saw, using an angle block to hold square rock at the
same angle when cutting all edges, so you have an object
with multiple flat sides, then grind it to a round shape on
a rotating coarse stone wheel with a drip from a hanging
bottle with a plastic hose and a drip control valve. This
cuts your time doing the actual sphere by many hours, and is
much safer than trying to grind the square edges in the pipe
cap covers and wasting grit.

You can achieve a final polish by putting the artificial
chamois purchased in any auto supply section, and
inexpensive, over the pipe cap cover and securing it around
the sides that hang down with a very heavy rubber band, like
the ones that come on vegetables such as broccoli and putting
your polish in the depression formed by loosely covering the
pipe cap cover.

Anyone wanting instructions for a simple and inexpensive
sphere machine contact me and I will put you in touch with
someone who has directions. You can use old wash machine
motors for power.

Lila Trudel
(Hale's Note: With that offer, that makes three sets of
plans for sphere machines available to you. One is from Lap
Journal, cited recently here; Lloyd Duncan recently sent a
set of plans which I hope to put up on the Internet. Lila,
why not get a set from your friend and send them to me at
3500 Cambridge Drive, Durham, NC 27707-4510? Thanks. hale)

Subject: Bio: Dee Purkeypile

Hello folks. My name is Dee Purkeypile. I am a hydraulics
engineer and I specialize in dam safety. My wife, Teresa,
and I were married five years ago, at which time she brought
me into the lapidary field.

We live in Austin, Texas and are members of the AGMS. I have
promised her that she can quit her job next year and devote
herself full time to lapidary carving.

We have multiple saws from 4 to 24-inch, many tumblers, 24
and 27-inch vibrating flat laps, a bull wheel, an old genie
and various carving arbors and rigs. We have collected many
tons of fine cutting material and we both intend to launch
ourselves into to the lapidary-art field as time permits.
The Lapidary Digest appears to be a wellspring of
information and a good resource to trade ideas, equipment
and materials.


Subject: BIO: Trevor Flory

I come to lapidary via my jewelry making hobby. I'm
particularly interested in carving semi-precious stones,
especially the quartzes. My "significant other" is into
tumbled stones which she collects by the dozens and
eagerly anticipates producing by the hundreds.

Trevor Flory
To unsubscribe from the Lapidary Digest, send a message to
Lapidary@mindspring.com, with the word UNSUBSCRIBE DIGEST as
the subject of the message. Other commands you may use are:
SUBSCRIBE DIGEST to join, HELP to receive a page of help
instructions on the use of the list, and DIR to receive a
list of names of all files in the Archives.

The command <GET filename> may be used on the subject line
(without brackets, of course) to obtain a copy of the file
named "filename". Type filename exactly as it appears in the
directory, including the extension txt. Do not cut-and-paste
filenames into the subject line.