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Lapidary blades


#1

hello, all-

I know this question may not get answered immediately, because so
many of us are off to Tuscon- but… My problem is, the trim saw that
I use to trim cabs now has a warped blade. Can this be straightened
out? I am using a blade that is about .20 inches thick, because it is
the only kind I have found that can be used in water.(I hate the
smell of kerosene-). It is a six inch blade, 1/2 inch arbor hole in
it. Barring straightening it out, could I use a tile saw blade just
to trim cabs? These I can get at Home Depot, instead of having to
wait for a blade to be delivered. thanks-

Anne Stickney


#2

Anne - Definitely go with the tile saw blades, for all but the most
expensive materials. Tile blades tend to be heavier weight, real
workhorses. For expensive materials like opal, lapis and sugilite you
should have a thinner blade on hand.

Jim Small
Small Wonders


#3

There was an article in one of the old rock magazines on how to do
this. It involved putting the blade on a flat surface and pounding it
with a hammer in arc after arc from the center to the outside, sort of
like pinwheel design. I actually tried it with one blade, but it
looked so sad when I got through, I just went out and bought another
one. I am under the impression that the companies that make blades
will do this for you, but it probably is cost effective only on the
larger blades. Sincerely, Rose Alene McArthur
@O_B_McArthurs


#4

Hi Anne. Yes you can use the diamond coated water saw blades marketed
for tile cutting saws. I buy mine from Harbor Freight, and mine is a
10 inch blade. Due to the high rotational speed of the blade when in
operation, it would be adviseable to pay the manufacturing company to
have them professionally correct the bend in your blade. Mine cost in
the neighborhood of $14.00 each, so feel it is more economical and
safer to buy a new one when needed. The higher the mohs scale, the
quicker they are used up. The only time I bent a blade was due to my
impatiently pushing too hard when cutting a piece of quartz. One blade
cut all the ceramic tile for my home, and is still being used for trim
cutting stone slabs.

Barbara Bequette


#5

Ann, There a variety of blades, that you could use, that are readily
available! First, it sounds like you are using a small saw. Depending
on the speed of the saw, a better blade might be a thin (.006 inch)
blade. These need to be run at between 3500 to 5000 RPM. They work in
both water and oil, cut fast and you can hold the stone in your hand.
If your saw is slower, maybe a replacement blade from Rio Grande, The
Rock Peddler or just about any Rock Shop! Second, If you are warping
blades .020 thick you are forcing your material into the blade too
fast! A suggestion is to change pulleys to give your saw a RPM close
to 5000 rpm and use some of the thinner blades! They cut faster, waste
less material and while they can cut your fingers they are pretty
forgiving! Good Luck!!

Rock Peddler is in Maine (800-416-4348) They will give good info
also! Rio Grande is in Texas(800-545-6566) Good info also
Both are excellent Mail Order Supply houses and are fast
turnaround!!g


#6

Hi Anne,

. My problem is, the trim saw that I use to trim cabs now has a
warped blade. Can this be straightened out? I am using a blade that
is about .20 inches thick, because it is the only kind I have found
that can be used in water. <

Most any blade can be straightened, providing the deformations aren’t
too severe. However, with that said, trying to straighten a 6 inch
blade would probably be an exercise in economic futility. The best
bet would be to replace the blade with a new one from a local or mail
order lapidary dealer. New 6 inch blades start at around $30.00
depending on thickness & mfg.

A tile saw will cut materials encountered by a lapidary, however,
they tend to be thicker than most saw blades. As a result of the
thickness, they can be wasteful of expensive rough.

If you don’t have a local lapidary supplier, Alpha Supply
(two@alpha-supply.com) has a good selection. (No connection to Alpha,
just a satisfied customer.)

Dave


#7

Hi Anne,

Yes, you can straighten a bent or dished diamond saw blade but it
takes some practise. You may initially warp it worse but (looking on
the bright side) the worse it gets the more practise you’ll get and
chances are eventually it will come right. That, in essence, is how I
learned.

Consider a metalsmith rasing a bowl. He’ll hammer a disc of silver or
copper, starting in the middle. The hammer blows thin and spread the
metal in the middle. But it’s surrounded by the rest of the unhammered
disc, so the stretched metal has nowhere to go with its added "length"
except up. In short, it bulges.

You want to do the exact opposite - get rid of a bulge. Therefore you
need to put the centre part of the blade into tension, so that the
raised area pops back down. You do that by putting the blade on an
anvil & lightly hammering all round the rim, trying to hit close to
but not right on the dimond bearing surface, and then spiralling
inward, but concentrating the blows on the rim to stretch that area
the most.

Keep checking your progress with a straight edge across the blade.
With practise you can true up the most amazingly bent blades that way.

Cheers & good luck
Hans Durstling
Moncton, Canada


#8

Hi,

For a 6" blade I wouldn’t bother - they sell them at wholesale
construction supply places for $10 or so and they stand up to real
abuse. If it is a larger blade it may be worth the while. I finally
got the courage up to try a couple of weekends ago on an 18" notched
rim (expensive) blade my girlfriend dinged into a nice S bend a few
years ago. Yes she is still my girlfriend - I had a spare blade and
was in a calm mood - besides good life partners are hard to come by
compared to lapidary blades. I applied a technique that used to be
used in the auto body profession called metal shrinking - basically I
heated the area worst effected just past the stage where the metal
turned from straw to blue colour to take some of the temper out. Then
using a 20" concrete blade as a backing plate I used a medium ball
peen to take the worst out by peening on both sides in a pattern from
the middle of the blade radiating outwards, heating and peening until
the blade was flat. Let the blade cool and check for any problems like
the hub flexing back and forth. Run a file over it to check for high
spots and you are done. I was quite happy with the results.

Some points to consider:

  1. There are no facilities near where I live to have this done
    (Barranca Diamond in California advertises they repair notched rim
    blades but with duty, tax etc… www.barrancadiamond.com ) so the
    blade was not of value in its bent state so I couldn’t make it worse

  2. This is a better quality segmented large blade so a replacement is
    pricey compared to a continuous rim electroplated blade

  3. I have had experience banging fenders out (cheaper to practice on
    and bondo can be used for any indiscretions).

  4. This blade has a fairly soft core so by heating I didn’t cause an
    issue with the overall temper

  5. Be real careful when heating near the rim as the diamond is held
    into the notches typically with silver solder

  6. If the damage extends past a bend, i.e. damage to the segments or
    cracks, write the blade off as it is not safe

  7. You do need a nice flat heavy piece of steel for this to work

  8. If nothing else it will relieve some frustration and it does make
    a nice racket

Happy Hammering,

Cameron Speedie
Island Gem and Rock