Angle grinders

[don dougan <dondougan@zzzzzzzz>]

Deb;

I agree with the others who have replied about getting a good brand -
usually you get what you pay for.
Another point I would like to make is that the grinders need to be blown
out with an air nozzle (while they are switched on and running no-load).
I make it a habit to use the blower nozzle (same line pressure as for
carving - 90psi) and blow into the intake and the exhaust ports after
every stone grinding session before I put the tool away.  Keeping it
clean seems to make my tools last longer . . . and if you have all your
air tools fitted with quick-connects then putting the air nozzle on the
line is literally a snap.

For what it is worth, you might want to modify the standard
over-the-counter air blowing nozzle -- here in the states you can't buy
an un-regulated blower nozzle.  A government regulatory board, OSHA
(Occupational Safety Hazards Administration) insists that air nozzles
provided by employers are either vented or stepped-down so as to reduce
the maximum pressure coming out of the nozzle to about 30psi (they're
afraid a dumb employee is going to stick it in an ear or eye and blow
their eardrum or eye out . . . ).
I don't employ anybody - dummies or otherwise, so after purchasing the
vented nozzle I remove the vented part of the nozzle and replace it with
a longer piece of small copper tubing (the nozzle is usually screwed in
to the blower handle and tapped to 1/8"NPT, and the plumbing department
of your local hardware store will have the adaptor fittings).  I have
several with different lengths and diameters of nozzle (some straight and
some curved), thus allowing me to get the air down in the bottom of
drilled blind holes, clean tool housing interiors, or just general
cleaning in the studio, etc.  If the blower nozzle you find doesn't
appear to be vented (an extra hole or holes in the side of the nozzle),
the trigger-operated plunger inside the nozzle may be the culprit that is
reducing the air pressure.  If this plunger has a stepped-down (very
small) valve-hole, it reduces the flow of your 1/4" or larger air line
within the tool.  You may need to enlarge that hole by boring the
disassembled part  (please note: boring may interfere with the O-ring
seals, and after boring you may have a small leak when the nozzle is not
being used but connected to pressure).

Abrasive blades versus diamond blades:
Aside from the initial cost, two other factors to consider in using
diamond blades versus silicon carbide abrasive wheels are time and heat.
 The diamond blades cut faster and more efficiently, creating less
heat-generating friction than the silicon carbide blades.  You finish the
cut more quickly, and the tool (and your workpiece) is kept cooler.  The
extra time you spend with an abrasive blade is extra wear on the tool,
and the extra heat also reduces the life of the tool.  I use silicon
carbide blades for dry-cutting sandstone and concrete - both of which
will ruin a diamond blade made for marble in minutes - but for most
dry-cutting operations I use diamond blades.

Buy good diamond blades too -- avoid the type with large segments made
for cutting tile, either use a continuous-rim (electroplated type for
soft stones and marble) or a rim with small (1/4" to 3/8" wide) segments
(sintered type for marble and harder stones).
A good 4-1/2" diamond blade suitable for years of stone cutting here in
the states starts at $40 and goes on up to over $100.  The best types
have flanges attached which allow the blade to be attached so none of the
grinder arbor-shank protrudes beyond the lower surface of the blade (like
the depressed-center wheel grinding discs you are probably using).
Theoretically, this allows you to cut infnitely large flat surfaces -- if
done in increments and the waste chipped away with each pass.

Good Carving to You,

Don

http://www.dondougan.homestead.com/indexdd.html