Re: [CAD_CAM_EDM_DRO] CNC HOT WIRE FOAM CUTTING

> Hello all--wondering if anyone has any ideas on cutting foam with a
> stiff hot wire "chucked" in the spindle. I'm needing to make a few
> small "doughnuts" out of foam rubber less than 1/2" thick.

Model airplane folks make new slightly longer tips for soldering guns
(the kind that have a heavy wire restiviely heated, not the
pencil-like irons) to cut foam details after cutting the basic shape
with a long thin heated wire.

You might be able to make such as a milling tool, but would need to
figure out how to couple high currents to the rotating spindle.
(Don't do it via the bearings!) Some nifty method could probably be
worked out using a sort of transformer, or even winding a generator
armature and using the spindle to rotate it in a magnetic field.

But I'd be more tempted to figure out how to put the work on a lathe
where the heated tool need not rotate. Or use a boring head in a
mill, but rotate the spindle by hand with some long flexible wire
leads. I guess if you have a CNC that can do circule interpolation
and manage to make a round cutter somehow the spindle need not rotate
at all. But a round tool would either need to be coaxial (in which
case the inside may get hotter than the outside) or complete the
current path via something below the work.

Use adequate ventilation as the fumes may be very bad from some types
of foam rubber and have an appropriate extinguisher on hand in case
you manage to set it on fire!

Chris