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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 58 - Wed 9/10/97
2. NEW: Lapping Agate Slabs
3. RE: Flat Vibratory Lapping
4. RE: Flat Vibratory Lapping
5. RE: Trim Saw Lubricant (Issue 57)
6. RE: Trim Saw Lubricant (Issue 57)
7. WTB: Rainbow Obsidian?


Subject: LapDigest News for Issue No. 58 - Wed 9/10/97

I wanted to get this out yesterday, but fate got in the
way!! Just found out that Anne's pacemaker battery is
getting weak and must be replaced. So we spent yesterday
at the Doctor's office and today at hospital doing all the
pre-op things. It will be replaced tomorrow at noon - an
outpatient procedure if all goes well, which I'm sure it

If any of you have experience with any of the following,
or have special knowledge of them and if you haven't told
me so, please write me a note and do so now. These topics
are being considered for future issues; if you have
experience or knowledge in any of them, after you let me
know, I will send questions and use your answers to help me
round out information into a usable form for publication
on the Digest. The topics are:
How do you make stone/mineral beads.
Band saws for rocks- uses, problems tips and what to avoid.
Canadian Labradorite and Spectralite.
Jigs and fixtures to aid in rock sawing.
Sphere Making.
Surface Decoration using Etching or Gold Leaf or
Sandblasting or scrimshaw or other methods.
Adhesives for use in Lapidary.
Flintknapping and heat treating of stones.
Next Issue should be Friday, if enough items come in by

Stay safe, wear protective face masks and goggles, and
above all, have fun!


Subject: NEW: Lapping Agate Slabs

-- My thanks to all who have submitted information on
Vibrating Flat Laps...but is there another way, besides
by hand, to polish Agate slabs?

I make a few clock faces, etc. But not near enough to
justify the $1000.00 cost of a vibrating Lap! Or, is
perhaps the Handlapping method of Glass plates or trays
and different grit wet-dry papers not as time consuming
as I would think?

Anyone have an idea of how much time is involved in hand
lapping a slab, from start to finish, say, starting with
100 grit and progressing up or down :> to the finer grits
and polish?

Thanks in Advance and take care.............Dave

Dave Daigle
Edmonton, Alberta, Canada


Subject: RE: Flat Vibratory Lapping

>From LapDigest #57:

<I have a Star Diamond flat lap, 12", that I picked up at
a yard sale. I've tried using it a few times with only
marginal success. The slab, or thunder egg, or whatever -
just wants to stay in one area of the pan. I've tried ...
,,,(snip) ... Is it a leveling problem? Is the pan worn
out? How level does the machine have to be? HELP!!!>

You could be running your lap on the dry side. Usually
when they start to dry out, the stones sort of stay still
near the center. You do have to add more than one stone
at a time. Just wait until you have enough material to
almost fill the surface of the lap. This way you will be
using the same amount of each succeeding grain size, from
coarse to polish, and getting more done.

You may also want to unplug the unit and turn it over.
See if the belt is running in the groove of the pulley or,
if you have a spinning weight, you may have to make
adjustments to where the weight rides. For the weight, I
would go carefully and do small adjustments rather than
moving the weight a lot a once.

Steve Ramsdell <>

*Noncommercial republishing allowed*

Subject: RE: Flat Vibratory Lapping

In regards to the question on splashing, messy vibrating laps
..Mine is messy as hell, and so I keep it covered with a
plastic "paintbooth" covered box. This way I can see into it.
Use heavy plastic sheeting. It can be crude (like mine) or
elaborate. It was cheap and served another purpose of holding
the moisture in the lap. Unless someone can tell me these
things can run clean, all of mine have to have a cover. I got
lucky on two of the other laps I have and have garbage pail
lids that fit the pan perfectly.

Brewster McShaad
Riverside, CA

<Quote if useful to you or other>

Subject: RE: Trim Saw Lubricant (Issue 57)

I have been following the thread on saw coolant with
interest. Most of the suggestions have merit and will work
well. The original question of what to use in a small trim
saw (4-6 inches) has been somewhat lost. The key word here
is "trim". Small material, usually already slabbed, is the
stuff being cut. Any of the water based additives on the
market will work well. Lube Cool, Crystal Cut and DiaCut
when mixed with water are essentially odorless and
stain free. All contain a rust inhibitor ( not rust proof)
additives as well as surfactants and organic lubricants.

On larger saws (8 inch plus) there are several very good
oils. We distribute Shell Pella A, others are Texaco Almag
and the Contempo product. Using diesel fuel, kerosene and
forms of antifreeze is downright dangerous. Being poisoned
or blown up is not my idea of pursuing a hobby. A classic
case of pennywise and pound foolish!

The key to good performance with a trim saw is matching
the blade to the job. Expecting a .004 or .006 blade to
last as long as a .012 or .025 for all trim chores is
unrealistic. Blades specifically made for water based
coolants are available (Lapcraft DiaLaser, Star Sunburst).

Peter Erdo
Graves Company

non-commercial republish permitted

Subject: RE: Trim Saw Lubricant (Issue 57)

<<The lubricating division of Shell Oil has an e-mail address
for technical questions, but I can't find it now (Damn!)
Will publish it when I find it. Shell Canada's address is
<> >>

In the San Francisco East Bay Area Pella is available at:

Golden Gate Petroleum
1565 Industrial Pkwy West
Hayward CA (510)783-6500

It is available in 5 gal. containers although the last time
I picked up 20 gallons they had to fill some from their 55
gallon drum. I don't think they carry a large supply so it
probably would be safer to call ahead. I paid $5.64 per
gallon in April 1997.

I have used this oil for over twenty years and have had good
luck with it. I don't think I would call it "odor or mist
free" but it is better than anything else I have used. I
still add a mist killer to my small saws and cut with a
respirator and rubber gloves.

The responses on slab saws binding probably gave the correct
answer but I had different problem once that gave the same
symptoms. I had about a year's use on a 20" saw blade when
it started cutting a curve and binding. After a lot of
measurements with no results I reversed the blade and the
problem went away. I have never had the problem again so I
can only guess that something I had cut had dulled one side
of the blade more than the other but I can't say I am happy
with that explanation.

Dick Friesen

-- non-commercial republish permission granted --
(Ed. Note: From the Internet: "Those needing technical
information on Shell products and lubrication can call the
Product Information Center from 7:00 AM to 5:00 PM central
time Monday through Friday: (800)-231-6950."

>From their web site:"Shell PELLA® Oils are versatile, low
viscosity, "mineral seal" oils with relatively high flash
points. It is named 'Pella-A' east of the Rocky Mountains."
They sent the following table for you techies:

Typical Properties of Shell Pella Oils

ASTM Pella Pella A
Method (w.of Rockies) (e.of Rockies)
Product Code 61906 61900
@ 40?C cSt D 445 6.1 4.3
Gravity, API @ 60?F D 1298 30.9 41.2
Pour Point, ?F D 97 -50 30
Flash Point, COC,?F D 92 265 265
Flash Point, PMCC,?F D 93 255 255
Aniline Point, ?F D 611 175 188
CU Corrosion @ 212?F D 130 1 1
Sulfur, %w D 2622 0.06 0.06

As an aside, the phone numbers or e-mail addresses of
technical info departments of large corporations are easily
found- just go to the internet and do a search with, say,
Alta Vista. hale)

Subject: WTB: Rainbow Obsidian?

-- Greetings, First let me say that this is a GREAT list!! I
am learning so much and have two binders full of the issues
so far. Thanks Hale and to all the knowledgeable folks who
have spread their wisdom. It makes our endeavors at lapidary
much easier, and our work areas much cleaner :>

Now, to the point...anybody out there know where I can
obtain some Rainbow Obsidian? I've never seen it but have
heard it's beautiful. I have had success with Black and
Mahogany and would dearly like to try and work some Rainbow.

Thanks and take care............Dave

Dave Daigle
Edmonton, Alberta, Canada
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