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1. LapDigest News for Issue No. 37 Thur 7/31/97
3. RE: Saw Sludge


Subject: LapDigest News for Issue No. 37 Thur 7/31/97

I am pleased to present a paper below written by Bill Ritter, President of Contempo Lapidary Equipment, on the selection of a lubricant for a diamond rock saw. Along the way, he has some advice on sharpening blades and how to inspect them to make sure they are indeed sharp. Thanks, Bill, for letting us print this paper.

Next week we wil have a three part paper by Bill Cordua on how to measure rock hardness, and what information it gives. All you ever wanted to know about Hardness of rocks and minerals! If you have questions on hardness or on specific gravity measurements or on any other physical properties of rocks or minerals, next week is the time to send them in .. Or send them in now, and I will keep them till then.

by Bill Ritter

My saw doesn't cut! My blade looks like it has diamond on it, but it
doesn't cut! My saw only cuts one or two inches into the material and
stops cutting! My blade cuts very slow and I have to really push it!
Sound familiar? I hear these complaints every few days. It took me
awhile, but now my first question is, "What are you cutting?" and my
second question is , "What is the cutting fluid?" Ninety-nine percent
of the time, I have saved the person the cost of a new blade and made
their saw work. What I have sold them is a one or five gallon pail of
the proper cutting fluid, and maybe a sharpening stick if they don't
have an old silicon carbide 100 grit wheel laying around.

Nobody likes the smell of diesel or kerosene (which many old-timers
use, and we stress DO NOT USE!) and the trouble of clean up and
disposal of the sludge. But for cutting hard stones like quartz-based
stones (agate, jasper, petrified wood, etc.), oil is the only cutting

We or our friends have tried about all the water-based coolants available
and we have not found one that does not "glaze over" the saw blade.
Basically what happens is that the water does not really lubricate, and
at the point of contact between the blade and the material, it gets so
hot that there is a micro flow of the metal bonding material over the
diamond. Once this happens, the metal starts to ride on the material and
the diamonds are no longer exposed. Then the blade stops cutting. It's
that simple.

To bring the blade back to life, you need to clean the metal away and
expose new diamonds. This is done by running several cuts into the old silicon carbide 100 grit wheel or use a sharpening stick which is about
the same thing. Then run your fingernail over the edge of the blade to
see if it catches on the newly exposed diamonds. Then use a loupe and
look at the edge of the blade to see if there are 2-4 diamonds in each
notch (like on a standard lapidary blade); they will be little black
dots. If a blade is badly glazed, it may take several cuts on the stone
to expose the diamonds.

Now that you have refurbished your blade, change your cutting fluid to
the proper oil. We define the proper oil as one that has a high flash
point (remember that diesel and kerosene are FUELS!) has no carcinogens,
has a very low viscosity (almost like water or a 3-in-1 oil), and has a
low odor. Contempo Lapidary has an oil which fits this description, called
"Finecut." To conserve your oil, strain the old oil and sludge through two
paper bags. It will come out almost as clear as new oil. Dispose of the
sludge properly.

For soft stones like marble, travertine, turquoise, or even granite, you
can use the water soluble coolants, as these stones are abrasive, clean
the blade and do not produce as much heat when cutting as the quartz type
stones. Also, you will not impregnate the porous stones with oil. But
remember, when you use water, even though it has a rust inhibitor in it,
you should drain the saw every night and wipe it down and spray something
like WD-40 on it to prevent rust.

I hope I have helped you in some way with this explanation about the
proper coolant to use in your saw. There are many variables with special
blades for different materials, but we will continue with that subject in
the next installment.

copyright 1997 by Bill Ritter; Published in the January Issue of ECLECTIC
LAPIDARY. Reprinted by permission of the author.

Bill Ritter and his partner, Ernie Wilson, purchased three of the oldest
lapidary companies (Highland Park, Beacon Star and Frantom) 11 years ago,
and blended them to form Contempo Lapidary. Since then, they have designed
and introduced one new piece of equipment almost every year. Contempo is
the leader in equipment for the small manufacturer and serious artisan.
Bill specializes in assisting customers looking for equipment solutions
to their production problems. You can find Bill at and

Date: Sat, 26 Jul 1997

Subject: RE: Saw Sludge

I've got no idea what to do with the sludge either, but I know of a
novel way to clean the oil in the winter up north.

Take a 5 gallon bucket, put one gallon of water in the bottom and add
the gooped up oil. Let it sit for about a week, then sit it outside and
let the water freeze. Pour off the clean oil. The sludge is stuck in the

Like I said before, it is up to you to figure out what to do with the

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