LAPIDARY DIGEST
Administered by Hale Sweeny (hale2@mindspring.com)
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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 70
2. RE: Types of Diamond Wheels
3. RE: Types of Diamond Wheels
4. RE: Types of Diamond Wheels
5. RE: Types of Diamond Wheels
6. RE: Types of Diamond Wheels
7. RE: Leaky Lortone Lids
8. RE: Leaking Lortone lids
9. RE: Indemnity form
10. Re: How To Make Opal Doublets
11. SHOW: Gaston County NC Gem & Mineral Show

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<MSG1>
Subject: LapDigest News for Issue No. 70

I have more files of threads in the Archives, but this
work is slow going, and it will be some time before all
threads have been so organized. As each thread file is
completed, I add the name of the thread file immediately
behind the thread, in the Index. So to find all thread
file names, download the Index.txt.

There are five very good letters describing the types and
brands of diamond wheels, and they go far beyond just
answering the original query. Hope you enjoy reading, and
learning from them as much as I have.

Next issue will probably be Friday.

Stay cool, be safe, and above all, have fun.

hale
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<MSG2>
Subject: RE: Types of Diamond Wheels

<<I have been following the thread on lapidary wheels. As
a newbie, I would like to know is the difference between
Galaxy and Nova wheels. I have talked with some people
about their cabbing machines and most of them have told me
to use Nova's. Is this just a brand name or due to the
method the diamond is bonded to the wheel.>>


If I remember rightly, Galaxy wheels are metal with the
diamond imbedded, and Nova wheels are a composition
covered wheel with the diamond imbedded in the surface.
Also, as far as I know, Galaxy are only available in the
rougher grit size like 80 and 220; their use also as far
as I know is limited to the roughing out of the cab.

regards
Richard
rcmac@juno.com or rcmac@aol.com

Non commercial free to use as desired...
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<MSG3>
Subject: RE: Types of Diamond Wheels

There are basically three ways to make a diamond wheel.
Electroplating, resin bonded and sintering.

Electroplating the diamond to a metal core is the most
common method of manufacturing lapidary diamond tools. The
three types of metal bonded wheels in our catalog are made
the same but the metal surface is different. The standard
surface is smooth and uniform. Easy to make and a consistent
preformer. The 'Diamondback" wheel has a criss-cross pattern
in the metal onto which the diamond is plated. The "Turbine"
wheel has a surface with straight lines cut across the face
of the wheel. Both these wheels are for very fast material
removal.

The Nova wheel is a resin bonded type. Diamond is mixed
with an epoxy resin and coated onto a sponge rubber surface.
This allows for sanding and polishing with less of a chance
to develope flat spots in a contoured surface like a cab.
It also provides a smoother finish compared to an equal grit
metal bonded wheel. Please note the words ..."sanding and
polishing". Roughing a rock with Nova wheels will wear them
out in a hurry. An alternative to Nova wheels is using
diamond belts on an expanding drum. Same results.

Peter Erdo
Graves Company

non commercial republish permitted
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<MSG4>
Subject: RE: Types of Diamond Wheels


Hale,
Galaxy is Diamond Pacific's designation for hard
diamond wheels for grinding and shaping. Nova is the
designation for "soft" sponge backed diamond wheels for
sanding and polishing.

Charles Ramer
ramer@dnet.net

Non-commercial republish permission given
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<MSG5>
Subject: RE: Types of Diamond Wheels

Two different types of wheel, with different purposes. The
Galaxy wheels are your coarse grinding wheels. They are
plated diamond grit over metal, and are rigid surfaces. They
are a fine quality wheel, comparible to most other good
quality diamond grinding wheels. The Nova wheels, on the
other hand, are your next steps, and replace the sanding and
polishing steps that might be done with traditional means.

They are a urathane rubber layer over a foam pad layer. The
rubber contains the diamond grit, and it can be anywhere
from around 600 (don't remember if they make a coarser one)
up to at least 14,000 grit (and maybe finer. Don't know.)
The coarser grits do your sanding and the finer ones polish.
Unlike the Galaxy's which are hard surfaces, and should be
used with a fairly light touch, the Novas are designed to be
used with substantial pressure, so the stone forces itself
into the surface a little. That gives you cushioned sanding
that conforms to the shape of the stone, removing "flats"
and the like, as well as scratches. Both the Galaxies and
Novas are used with a water lubricant (Unlike other forms of
diamond sanding and polishing methods, where the compound is
applied to a belt or disc, and run slow, without much
lubricant.

Also, both Galaxy and Nova are brand names. For both types
of wheel, especially for the diamond plated grinding wheels,
there are competing products or methods from other
manufacturers. For example, 3M makes diamond sanding belts
and disks that will compete with the purpose of the Nova
wheels, though using a different type of wheel. These belts
are used with rubber expanding drums, and the result is
similar in function to the Nova wheels. The disks are
useful as well for those with smaller machines that cannot
mount a whole sequence of the Nova wheels for the whole
sanding and polishing cycle. The disks mount on the end of
the shaft, and are typically spin on/spin off mountings,
easy and quick to change, but less convenient to lubricate,
and sometimes more awkward to work with. Matter of taste,
choice, need, and budget...

Hope this helps.

Peter Rowe
<PWRowe@ix.netcom.com>
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<MSG6>
Subject: RE: Types of Diamond Wheels


Galaxy and Nova are both made by Diamond Pacific, the
Galaxy wheels are grinding wheels, the Nova wheels are for
sanding and pre-polishing.

Selecting which diamond products to buy can be traumatic
for an experienced cutter as well as a beginner. The cost
gets your attention immediately and the advertising does
not tell you enough about the difference to make a
selection. The best way is to find someone using the
products you are interested in and talk to them. With some
luck they might let you try them out. Get involved with
your local gem club. You will probably find several
knowledgeable people to talk to.

For what it is worth, here is my personal opinion based
on about 25 years experience working with some of the
diamond products. Remember technique has a strong
influence in the results and if your technique is
different than mine (almost a certainty) your results
may be different.

Diamond Pacific:
Excellent choice for beginners. The Nova bonding process
is very tolerant of errors in pressure and feed rate,
just keep them wet. I personally prefer to use a flow
through water system rather than the spray system that
comes with the Titan/Genie/Pixie but the spray system
works. I have had some problems with materials like jade
but over all this is the place I start all my beginning
students.

Crystalite:
Good selection of grinding wheels with several special
shape wheels if you can use them. They also have a diamond
grinding belt set that fit expandable drums. If you are
limited to a small arbor, you can do your course grinding
on your sanding drums with just a belt change. The only
problem I have had with the grinding belts is that I can't
get the life out of them I think I should for the price.
I have had good luck with any of their regular grinding
wheels.

Their diamond sanding belts are designed for expandable
drums and I find I use them oftener than any others I have.
But they require "breaking in". I also prefer to use them
at 1140 rpm rather than full arbor speed (1725 rpm). A new
belt at 1725 rpm will pound small chips out of an agate if
your not very careful of your pressure. The finer grits
also require "dressing". Crystalite sells a dressing bar
and I find I use it every few hundred stones, if I don't,
the belts will start leaving deep scratches.

I like their Flexodiscs for polishing and experimenting
with new polishes and techniques.

Raytech:
The "True Circle" belts are excellent for agate but are
hard to use on softer stones. The belts are harder than
other products, and when used on softer stones it is
difficult to keep from developing flat spots. They do a
better job than most on jade. I find I use them most on
flats and the back of cabs.

3M:
Their "Imperial Cabbing Belts" are somewhat different than
other manufactures products. They feel more like silicon
carbide when you are using them. The backing is soft and
the surface is very smooth. I have had good luck going
from their 220 grit directly to their 15 micron belt. A
new 15m belt cuts more like a SC 400 grit but the scratches
are finer although not as fine as a Nova 1200. I think
they control undercutting better than most and until I
started using "Rapid Polish" for jade I had the best luck
with their 6 micron and .5 micron belts. These belts also
wear out faster than most.

3M also has a plated and resin bonded belt set but I have
never used them. I would like to hear from someone who has.

Hi-Tech:
Their "All You Need Machine" is worth considering if you
don't plan to do a lot of cutting. For what you get for
your money, their machine is hard to beat. I find it hard
to do a lot of cutting with a horizontal system, but I
learned to cut on a vertical wheel. Maybe I am just too
old to change. I think the horizontal wheels are harder to
keep clean. The machine does not come with their 3000 grit
disk, you might want to add it. I think their 1200 grit
disk doesn't leave the cab ready to polish. They
demonstrate at a lot of shows, find one and try it out.

Diamond Compound:
I know this works and I have seen excellent work done with
it but I don't care for it. I have problems determining
when the cabs are ready for the next grit. I have been
told it is a good choice for jade but every time I use it,
it orange peels.
*********
If you have had different results, have something to add,
or have used other equipment, please share it with us.

Dick Friesen
friesenr@ix.netcom.com


-- non-commercial republish permission granted --
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<MSG7>

From:
Subject: RE: Leaky Lortone Lids


In regards to the "lids" of Lortone tumblers, make sure
the lid, and the area the lid fits in, is clean and dry.
If you have to force, or lean on, or stand on it to get
it on, then something is terribly wrong!!

Put a sugar-cube size piece of Ivory soap in the barrel
for every phase, and use hot tap water to one inch below
the surface of the rock. DO NOT BURP!! It is unneccessary
if your tumbler is used properly! I run my coarse grit
for 19-21 days without opening the tumbler,and I can count
on one hand the times in 10 years the barrel has leaked.
Practice, practice,
practice!

ROUGH&TUMBLE
amyr@rosenet.net

Non-commercial re-publish permission granted.
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<MSG8>
Subject: RE: Leaking Lortone lids


I have been running between 2 and 6 Lortone barrels non-
stop for about three years and have only had leakages for
two reasons that I can trace. By far the most common was
failing to clean the lid and lip perfectly - I think I
have learned that lesson ! I have had problems with the
rubber covering of the lid pulling off the edge of the lid
(and not because of overtightening) A good dose of super
glue (is it crazy glue in the US ?, anyway the stuff that
sticks your fingers together in about 2 seconds flat) run
round under the flange cured the problem for several runs.

Andy Parker
andyp@netcomuk.co.uk

-- non-commercial republish permission granted --
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<MSG9>
Subject: RE: Indemnity form


Gilbert F. Douglas,<KE4NRL@juno.com> wrote, in Issue 68:
<<I am trying to find the best wording for an indemnity
form to be signed by each person using the workshop and
equipment.>>

I thought I read a request for release forms. I am very
very interested in this. I haven't taught anyone in a
few years because of the fear of law suits. This is a
very important part of letting someone work on your
property with your tools. I don't know of many people
that can afford the kind of problems that can result from
suit. You don't get rich teaching, but it is rewarding
for both.

Steve
sramsdel@prairienet.org
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<MSG10>
Subject: Re: How To Make Opal Doublets


I have no experience at all in making doublets but I want
to start in the near future in making doublets or even
triplets. A few weeks ago I bought a small book titled:
"A Gem Cutter's Handbook. Advanced Cabochon Cutting" by Jack
R. Cox. Copyright by Gem Guides, ISBN 0-910652-14-7.

This is a very nice book which treats in detail the
different cutting methods including doublets, triplets. Also
opals (even different types) are described how to use them.
This is a very practical book (or a manual).

Anyone else with experience in making doublets/triplets?
Please mail them!

Best regards,


Fred van heuveln.
vanheuveln@ecn.nl
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<MSG11>
Date: Wed, 08 Oct 97 08:03:46 PDT
To: rockhounds@infodyn.com
From: ewenglish@blueridge.net
Subject: Gaston County NC Gem & Mineral Show


Looking for someplace to go this weekend?

Try Gastonia, NC for an outdoor show. The weather is
supposed to be great! Admission is priced right $0.00 for
adults, kids free. Parking is free, the air is fresh and
free.

Oct. 10 through 12, Gaston County Gem & Mineral Club,
19th Annual Gem & Mineral Show.
On the Nature Trail at the Schiele Museum,
1500 E. Garrison Blvd. Gastonia, NC
Hours 10th & 11th 9 AM - 6 PM; 12th, 9 AM-5 PM.


While I won't be there all of the time, stop by the Club's
Canopy and tell
who ever is there your email address.

thanks,

Earl English
ewenglish@blueridge.net
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