Generator (was ATM Blank statistics?)

[Anthony Stillman <atmer@flash.net>]

For dough, any blank can be slumped or generated.  Large and steep curves
need it.  Both processes use special equipment which tends to exclude the
less than deranged.

Not wanting to spend the money on fuel for annealing, I'm currently in the
process of building a curve generator.  It uses my table top drill press to
belt drive the tool.  The tool is made from seven inches of six inch
diameter, eighth wall steel tube capped with a half inch thick steel
insert, which is welded in place.   I've trimmed the tool to length and
drilled and taped a 1/2-20 center hole in the end cap to engage the arbor.
To do, hack saw the slots at the bottom of the tool, I'm not looking
forward to this.  A Bodine 150RPM (Einsteins Attac, thanks Gerry) also
geared down by belt and mounted in a soft steel sheet metal case
(previously the box a '386SX came in) will drive the part table.  Of course
I'd like to have the part table suck the part down with vacuum, like a
Strasbough, but I think I'll concern my self with drilling the mounting
holes for the Bodine first.  With a few more parts and in a few more days
(OK, but weeks are composed of days) this rube goldberg will be chugging
away.  It should generate, in a single pass, blanks to 12 inches in
diameter.  I plan to tilt the table to adjust radii.  To keep things from
walking while in operation I'm going to bolt both the box and bench the
tool/drill press is contrived on to the cement floor.  I'll do this with
lead expansion inserts, currently the only way I know, unless someone has a
better idea.

Pinky, we stand on the verge of world domination.

When starting with a generated surface, 220 is coarse enough to adjust the
surface and the molded tiled tool.  There can be value in starting as low
as 80 to remove sub-surface damage, just as there is great time savings in
starting at 30 microns coming off a Strasbough diamond generater with a
Zerodure blank.


>...numbers of mirrors
>being made from precurves...(versus)...flat blanks?

Not a clue.  I'de guess
Including pros, maybe a 1000 to 10,000 to 1
Only amateurs, maybe 1 in 20 to 1 in 50

>(do)...precurved blanks...use...carbide or aluminum oxide in the larger grits.
>John L

Though aluminium oxide comes in coarse sizes, it sucks for grinding, it
breaks down quickly, leaves a ugly (dificult) mud, and being softer than
carborundum, moves glass more slowly (actually it moves glass like sand,
ie, f---).  In fine grits, alumina leaves a fine surface with low
sub-surface damage, and shallow pits, hence the surface polishes out well
and quickly.

Anthony