Re: [CAD_CAM_EDM_DRO] Re: Engraving on Mill

Some grades of Plexiglass/Perspex are prone to melting. You can get high
temperature versions that do not have this problem.

Les


I have been experimenting with engraving in wood and plastic and
found that 30,000 RPM causes the plastic (mostly tried Plexiglass) to
melt and bind to the cutter. I have found that 10-20,000 better. I
did not think of using air to cool/remove the chips though. That
sounds like a good idea.

The cutters I was using were double flute, perhaps the engraving
cutter you describe would work better :-)

Steven Manzer

--- In CAD_CAM_EDM_DRO@y..., JanRwl@A... wrote:
> Joe:
>
> This is a task I have personally only tried one time, where I made
some
> simple lines and engraved "AC" on a tiny switch-panel, by-hand,
not "CNC".
> But I DID have some advice, both verbal, and "look and see,
yourself!" from
> an old (now gone) engraver-friend: An "engraver's point" is a
60° "half
> point" (first, grind a 60° point, suggest you use a 1/8" or 1/4"
dia.
> solid-carbide "blank", so that the point is about 0.005" off-center
with the
> blank's O.D. Then, grind away HALF of that cone, so that the flat
you have
> just ground passes through that point, and the concentric center-
line of the
> blank. THAT, then, is a standard "engraver's point". OH, you
have to pay
> attention to which SIDE of the point you grind away, so that the
cutting will
> be standard-direction (CW looking DOWN, or CCW looking "up, into
the rotating
> bit"). If you have ultra-fine diamond grinding machinery and
experience,
> you might then grind an "edge flat" about 0.015" wide along the
leading edge
> of that "half-cone", and this may make that tip studier for metal-
cutting.
> Look at a standard cutter or even drill-bit. See the edge behind
the "sharp
> edge"? That's what I am trying to describe. That is concentric
with the
> tool.
>
> Spin that at 10,000 RPM, using WD-40 for aluminum, or AIR if
engraving
> plastic or wood. OH, if plastic or wood, suggest you spin it at
30,000 RPM
> if you can! Yep!
>
> Jan Rowland


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