Re: [CAD_CAM_EDM_DRO] Routing speeds and feeds for plastic "sign" material

In a message dated 9/23/2010 1:48:52 P.M. Central Daylight Time,
alan@... writes:

Everything I do just seems to melt the plastic onto the cutter!<<
First, the cutter has to be RIGHT for that kind of material. It is
usually called something like "Laminoid". The cutter should have ONE "flute"
(cutting-edge", and kinda look like a pencil in ONE direction, and like the
conical part of that was 50% removed, in the 90% direction. The "cone"
should be such that ONLY the cutting-edge is at the greatest O.D., and the
folowling 50% of cone-surface should NOT contact the work, once that cutting
edge has removed material, ahead.

A "metal cutting" pointed "mill-bit" with 2 or 4 flutes is NOT right for
engraving!

If this cutter ("engraver's point") is right, that particular material
likes very high RPM, depending on the WIDTH of the lines you will be
engraving. For 1 mm. and narrower, anything from 10K to 40K RPM would be ok, IF
that edge is sharp, and there is proper clearance, as described above.

Cutting-rate? YOU do the math, but so that each pass of the cutting-edge
removes about 0.005". This laminate material is MADE for such engraving.
It is NOT metal!

I usta save PCB drill-bits when the "drill part" busted off, as the 1/8"
shanks made excellent engraving-bits, if the user had a proper diamond
cup-wheel, and EXPERIENCE. I'd give my busted PCB-drill-bits to an engraver
friend, and he was happier'n a pig in wet [stuff], as he could grind 'em "to
suit" different materials, like aluminum, brass, mild-steel, Laminoid, etc.
He had DECADES of experience with such, and just got too OLD for that
stuff, so is now pushing up flowers in CO.

Any advice or pointers to some reading material greatly appreciated.<<

Lotsa luck! (Visit an engraver! ASK for show-and-tell!) Jan
Rowland




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