"Abrasha" wrote in message
...
Andrew Werby wrote:
"norwick" wrote in message
...

I need to cut a spiral onto a silver rod.
The sides of the cut can be at 90 degrees/and/or inclined. I envisage
this to be done by a lathe (milling machine?).
Diameter of rod could be 10-15mm,
spacing between edge of the next groove ca 3mm,
groove width & depth ca 2mm (ideally there should be some scope for
visual considerations).
Non electric system would be acceptable (or very slow speed lathe),
machine size should not be more than 1m, weight under 50kg.
Cost should not be more than $1000-1500, but this assumes that it can
be used for other applications, eg cutting tool steel etc.


[You could do this on a miniature CNC milling machine (like the Taig
mills I
sell) equipped with a rotary table, chuck, and tailstock. You'd need to
program the toolpath to advance the tool along the X (long) axis while
rotating the A axis (the rotary table) so that the grooves were properly
spaced. A ball-end tool would give you a round-bottomed groove; a regular
endmill would give a flat-bottomed groove. The weight and size of this
machine would be about what you're asking for above, but the price would
be
higher - about $3k, with the accessories you'd need. These machines can
be
used for many other things, but for best results with tool steel anneal
it
first, and use carbide cutters.]

The motor that typically cames with the Taig does not have enough power to
cut a
2 mm deep groove in a 15 mm diameter silver rod. The cutting force would
stop
the spindle dead in it's track, or the rubber band (the drive belt that
comes
with the Taig is no more than a big rubber band) would just slip.

Abrasha
http://www.abrasha.com

[Want to bet? Taig recently started providing a bigger motor with their
mills than previously. The 1/4 hp Franklin motor now standard would have no
problem cutting a 2mm groove in a piece of silver - or a piece of steel, for
that matter, in one pass, if one went at an appropriate speed using a 2mm
2-flute cutter. It could also make multiple faster cuts at shallower depths.
The Gates drive belt, while it may superficially resemble a "big rubber
band" is actually quite resistant to slipping, when tensioned correctly. The
pulley settings can be changed to provide more torque, or more speed, as
needed. Have you ever actually used one of these mills?]

Andrew Werby
www.computersculpture.com