Administered by Hale Sweeny (email@example.com)
This list digest contains the following message subjects:
1. LapDigest News for Issue No. 83 - Friday 11/14/97
2. NEW: Lapidary Glues and Cements
3. RE: Making Diamond Tools
4. NEW: Help Me Find a Rock Shop near I-95.
5. RE: Cab Thickness
6. WTB: SiC Tumbling Media or Grit Wanted
7. WTS: Lapidary Equipment
8. WTS: 14" Slab Saw
9. WTS: Used Lapidary Equipment
Subject: LapDigest News for Issue No. 83 - Friday 11/14/97
If you do channelwork, would you please write me and tell me
so? I need some information about it.
There are several topics in the wings which will be published
in future issues. They are:
.. doublets and triplets
.. how to do channel work (mineral inlay)
.. lathe or tub turning
.. mud saws
.. rebuilding old lapidary machines-revisited
.. polishing with diamond
If you have any other areas you would like to see covered,
please send your suggestions to me.
Mark Case and Jan Maclellan both wrote to warn of a scam by
"government agents" in Nigeria who need an "off shore
account" to transfer $31 million in war surplus money; Mark
has been contacted four times this year. This is a scam. They
seem to get their 'sucker lists' from the net.
Our Archives may soon be available on Carol Bova's website;
we are working out the details now. If they do go up on her
website, I will still maintain an Archive as it is now so any
of you without web access may still access the Archives.
We will be able to show drawings, sketches and photographs
on a web site!
Have a safe and warm weekend, and above all, have fun.
As Mel Albright likes to say: Hug or call someone you love
today! Good advice.
Subject: NEW: Lapidary Glues and Cements
I use a variety of glues and epoxy cements for different
lapidary purposes. For instance, I use plumbers epoxy for
backing and reinforcing fragile stones, super-glue or
5-minute epoxy for cold dopping and "Devcon 2-Ton" clear
epoxy for doublets and triplets. By and large, they work
pretty well but I have an uneasy feeling that much better
materials probably exist for at least some of these purposes.
Within the last year, I recall an article in LJ about
laminated gemstones in which reference was made to "the new
glues". It showed multicolored rods made by cementing
gemstone discs together and I had the impression that the
stones would break before the joints failed. I don't think
this would be true with any of the glues that I use. Can
someone please contribute information or share their
experience of super strong glues and their properties?
(Ed. Note: Yes, Goeff, I remember that article, and remember
being irked that they did not identify what the 'new glues'
were. I hope some members of this list can shed some light on
these or other 'new' glues which might be very useful in
lapidary work; hope to hear from you. hale)
Subject: RE: Making Diamond Tools
I enjoyed the series on diamond tools and would like to see
more on this subject. Could you explain the difference
between sintering & plating, and is there a simple way to
make homemade sintered laps coarse enough for rough shaping &
Thanks for any info you can provide & thanks for the effort
spent in maintaining this LapDigest.
(Ed. Note: Anyone wish to explain for Noel the difference
between sintering and plating? About the laps... anyone know
how to make a coarse lap by sintering? hale)
Subject: NEW: Help Me Find a Rock Shop near I-95.
A friend and I are going to Norwell Mass. the weekend after
this. We'll be travelling along the I-95 from Bangor Maine to
somewhere near Cape Cod. I don't know the area, and am
looking for rockshops say within 30 miles of the I-95, and
preferably rock shops that are worth making a detour for.
If you know of any, please send me their name and location
Subject: RE: Cab Thickness
Recently I asked in Lapidary Digest how thick a cab should
be, and got several responses. I had asked the same question
last March on Rocks-and-Fossils mail list, and this led to
quite a discussion. I collected those responses, and filed
them away and over the past eight months, forgot where they
were. I found them recently, and thought they should be
added to the discussion we recently had; these are the
responses, edited to remove the personal comments, and
republished with their approval. But first, here is the note
I originally sent to rocks-and-Fossils mail list:
I've never thought much about a proper thickness for a
cabochon, but I read that moonstones should have a 'high
dome', and this started me thinking about my cabs ... I guess
I have usually cut slabs for ordinary cabs about 1/4 inch;
thus all my normal cabs have been a little less than 1/4"
thick. But this might not be best.
How thick should an oval cab be? Some constant thickness?
Some proportion of the width or length? I would appreciate
any advice you can give me.
Response from David Lipscombe <firstname.lastname@example.org>
I don't know of an official height for cab's, I cut my slabs
about 1/4 to 3/8 inches thick. From viewing cab's at shows
and stores it seems to run about that for standard material.
For star and chatoyant materials they some seem to be higher
but I've seen some that were not.
I have not seen but would like to see the rules or
instructions that a judge uses for grading a display case of
Response from Earl English <email@example.com>
I don't believe that there is any rule on thickness of cabs,
though the larger the cab, thicker the slab, easier to get
good even radius across the surface. That I think is the real
controlling factor, the dome should be a nice, even radius.
I have used Autocad to generate drawings of actual cabs,
generating the radius from center to edge then calculate the
angle tangent to the radius, just to get an idea of the angle
to hold the dopstick while roughing the blank.
Cats eye, and star stones are usually cut with a "high" dome,
usually from small pieces of rough, so "slab" thickness is
not a consideration.
Naturally, thin section to width ratio results in "low dome"
Sorry there isn't a better answer, keep working at it until
the stone looks good. Remember that you will lose about 1 mm
in overall thickness in the grinding/sanding operations.
Response from Mel Albright <firstname.lastname@example.org>
Hale - how high is the sky? IMHO, The answer is that there is
no answer. Just from my eyeball and engineering background, I
suppose the 1/4 inch thickness derived from aesthetic
reasons. A compound curve approaching a catenary works out
very nicely at that thickness. Less and the curvature is less
satisfying. More and it is also less satisfying. The only
exception I have ever seen was cats eye stones where an
extreme curvature brings out the tricks of light that make
the stones attractive.
Response from Tim Fisher <email@example.com>
Starting with 3/16" to 5/16" slabs seems best for cabs; the
larger the cab, the thicker the slab. I have seen high-domed
cabs like the one you describe done in inappropriate
materials (i.e. agate) and they look ugly, IMHO. High domes
show off chatyont materials like tigereye best; low domes
show off banded materials with "sheen" like rainbow obsidian.
Response from Roger Pabian <firstname.lastname@example.org>
The thickness of a cabochon depends mostly on what you want
to do with it. It doesn't even have to be a dome. If you are
cutting things like iris agate, a thin, flat slice polished
on both sides is fine. On the other hand, if you are cutting
chatoyant (eyed, tiger eye, cat's eye, etc.) or asteriated
(starred garnets, rubies, sapphires, etc.) stones, a fairly
high dome is needed once the proper orientation is
determined. If the star or eyed stone is a round stone, you
will get the best effect with essentially a hemisphere. If
the starred or eyed stone is an oval, the dome should be half
the height of the short axis of the oval.
Stones like moon stones that cause the billowy effect usually
need a fairly high dome to produce the best results, whereas
some other feldspars like labradorite (or spectrolite)
produce the best interference colors with a fairly low dome.
If you are doing things like agate, petrified wood, jasper,
flint, picture jaspers, etc., let the stone determine what
will be the best profile---high or low, and don't sacrifice
an attractive pattern or color scheme to fit some artificial
Its also important to determine whether you want the stone
for use in jewelry or simply as a display item. You can take
a lot more liberties with the latter as far as size, profile,
Hope that provides a few answers for you. I get similar
questions from students in my gemology class at University of
Nebraska and in lapidary classes at the Lincoln Park &
From: Gilbert Shea <email@example.com>
Date: Wed, 26 Mar 1997 19:56:06 -0800
Subject: Re: How high is a cabochon dome
Mel Albright wrote:
<<It also has to do with the angle of dispersion for the
stone you're working with, the same as in faceting.>>
A lot of stones have their own angles which you can take
advantage of when cutting. That's typified in such materials
as Stars and Cats Eyes, or Opals or Moon Stone/Labradorite,
Response from John <firstname.lastname@example.org>
I cut a lot of calibrated and freeform cabochons from slabs
1/8 to 5/16 thickness and usually the the dome is 85% to 90%
of the thickness when I am through with it.
Usually a cabochon cut from moonstone or other sheen or eye
stones is anywhere from 1/4 to 3/8 thick (12X16MM to 22X30MM
rounds ovals) and the dome height is goes up in height the
larger the cabochon. If you decide to cut smaller cabochons
of the above - experiment with heights.
Subject: WTB: SiC Tumbling Media or Grit Wanted
Our local gem and mineral club has traditionally stocked
lapidary supplies (which we try to purchase in bulk to save
money) for use by club members. Our supplier of tumbling
media has gone out of business, and we are in need of media.
...I was wondering if any of you are in the position to cut
us a nice deal on several hundred pounds....e-mail me.....
Subject: WTS: Lapidary Equipment
Below is some excess lapidary equipment I have for sale.
Graves: Cabmate, like new, used very few hours.
6"- 180 diamond wheel, 6" diamond saw blade w/ table, 2
speed motor, 110 volt, light, water can, instruction manual.
(Cost $625 + shp).... Sell for $375 + shipping.
Graves: Spool Polisher "Complete" item # 13-051 like new,
low hours (5), includes diamond compounds, (Cost $182 + shp)
Sell for $100 + shipping...
Crystallite 180 grit diamond wheel 1 1/2" wide, low hours of
use on soft material (amethyst, tigereye, etc) $85+shipping.
Some part ( 1/2 or less) trade considered... I'm looking for
rough: tourmalated quartz (clear quartz wtih green, black or
other coloured toumaline), tourmaline (watermelon, etc.),
cacoxanite, moldavite, opal, Australian agate, malachite,
unique and unusual rough is my "thing". See my web site for
finished jewelry pieces.
I Love this list!!!!
All the best in all things,
Wm. Augustus Mason
Subject: WTS: 14" Slab Saw
I have gotten to old to collect, slab or handle large chunks
of rough. Rather than let the saw go to waste I want to sell
it for $500.00 or best offer. Consists of "overhead" 14"
pump, motor, several used 14" blades and a large floor stand.
Must be seen, as it is to large to ship. contact me off line
for directions (Philadelphia PA. area. I am not a dealer,
just cutting down on equipment.)
Subject WTS: Used Lapidary Equipment
Our rock shop, Rough & Tumble, sells new and used lapidary
equipment. The used equipment has all been inspected and, if
necessary, has been refurbished and is ready for use. Send an
e-mail message for a complete list of available pieces and
prices. The present inventory includes: 12" Chop Saw, 24"
Covington Slab Saw, 3 Barrel Tumbler, Lortone 6" Combo Unit,
15" Lortone Vibrating Lap, 20" Rociprolap, Star Diamond 5"
trim saw and several others.
Frank and Mona Frabbiele
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