Joseph Herbert on fri 11 jul 97
I have done wheel grinding on a bench grinder - very bad. Too much dust,
heated glaze popping off the ware, the pot bottom bouncing on the wheel. I
have done pot grinding with a hand-held angle grinder - 10,000 rpm. Somewhat
better but still hot spots, and DUST. I have ground pots with a diamond
wheel in a dremel-type tool, smoother finish, FASTER, more selective cutting,
still dusty.
The current choice for grinding is a 10 inch grinding wheel. Purchased from
an industrial surplus place in Newark, Ohio for $4.00. Glued on its side to
a bat and used wet. Dribble some water on, rotate the wheel head, move the
pot bottom round and round. Apply more pressure, apply less pressure, it s
not hot, there s no dust, it s slower, it s quieter, it s not exciting at
all. I really find it better for me.
On a more general note. Grinding wheels vary by shape, abrasive composition,
abrasive grain size, and kind of bonding agent and amount of bonding agent.
The common abrasives are aluminum oxide (corundum), silicon carbide, and
diamond. Natural sandstone wheels are quartz as are "Arkansas" stones. The
size of grains are given by a mesh number and the larger the number, the
smaller the grains. 10 is really coarse grains while 600 is very, very fine.
(sound like sandpaper? Same thing) The grains can be barely adhered to
each other, an open textured wheel, or they can be totally encased in
adhesive. The bonding adhesive can be tough or brittle. The combination of
amount and properties controls how fast the grains of abrasive leave the
wheel, exposing new ones. An open textured wheel, like the Green Wheel" of
Axner s post will loose grains fast keeping fresh cutting edges on the
surface and keeping the wheel from clogging with ground material. Select a
wheel that is fairly open and that has waterproof bonding agent if you are
going to try the water torture method.
A method that has occurred to me but that I have not tried is the flat
bottomed basin method. You throw a big, 12 - 14 inch diameter basin with
thick bottom and a low vertical rim. The rim meets the bottom in a curve.
The bottom is flat but grooved. After this piece is fired to maturity, it
is mounted on the wheel head, and water and silicon carbide grit is added.
The rim and grooves keep the grit in and rubbing the bottom of the pot
around in this slurry of water and abrasive should easily clean off glaze
goobies. Conceptually, it seems good. You can throw the basin your self and
buy the grit from a lapidary supply house.
Joseph Herbert
JJHerb@aol.com
Debi Beck on mon 14 jul 97
>The current choice for grinding is a 10 inch grinding wheel.<
Why do you (and others) grind the bottoms? I have not seen this. Is this
instead of trimming?
TIA, Debi
Jim Duffy on wed 16 jul 97
The grinding is going on after the pot is fired, and for some reason,
has glaze stuck to the shelf, or a rough foot. Grinding is the last
thing you can do to the pot to save it if there has been a glaze fault.
I liked the idea of smoothing a rough textured bottom to save the coffee
table. That is customer satisfaction!
Debi Beck wrote:
> ----------------------------Original
> message----------------------------
> >The current choice for grinding is a 10 inch grinding wheel.<
> Why do you (and others) grind the bottoms? I have not seen this. Is
> this
> instead of trimming?
> TIA, Debi
| |
|
