Tex Brashear wrote:
>
> Does anyone have any experiences to share about working with a plasma
>cutter to do intricate fretwork designs on gnomons and dial plates? Any
>tips or good external references would be appreciated.
I've contracted for plasma cutting 12mm stainless steel for two large polar
dials but was advised:-
1) polished plate would be locally degraded by plasma cutting i.e. cut first
the polish afterwards.
2) allow at least 3mm 'waste' to be machined away from the cut plates.
If it's precision you're after and repeatability then you should perhaps
investigate 'water jet cutting'. Water, loaded with a small amount of
abrasive, is pumped through a 1mm dia. hole in a diamond at 40 000 psi. The
workpiece - almost any material in thicknesses up to 8" - is placed over a deep
water tank to catch the jet and the profiles are traced by CNC software. The
payback comes with multiple production as the programming for a small scrolled
gnomon is about £20 (UK).
Tolerance to line is excellent with good square edges (the jet diverges very
little) there are no burrs and the finish is almost ready for polishing. The
process noise is close to that of a jet engine feet away.
Hope this is of interest.
Tony Moss
