Re: Routing speeds and feeds for plastic "sign" material

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Alan Rothenbush <alan@...> wrote:

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> I'm tired of having a CNC milling machine and a CNC PCB router and still labelling things with a Dymo labeller!
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> So I bought some of that standard sign material .. you know the stuff, soft plastic, thin black layer on the top, white below.
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> First step was to route a hole for a fuse, next step engrave some lettering below the hole.
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> I'll be darned, though, if I can figure out the speeds and feeds and whatnot for this material.
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> Everything I do just seems to melt the plastic onto the cutter!
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> Any advice or pointers to some reading material greatly appreciated.
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> Alan
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> Alan Rothenbush
> Client and Research Services
> IT Services
> Simon Fraser University

It's as much about the bit as the speeds and feeds. There are bits made for cutting that material (usually available from the same sources as the material or any good sign supply). Melting plastic says there is too much friction on the cut. Engraving bits are v shaped and basically have two cutting edges with a flat cutting edge and no spiral. We cut a lot of plastic for cases and some plexiglas and we use a small two flute bit (upcut) with a very course spiral. We lower the router RPM and feed at about 15 to 30 IPM. That is cutting all the way through 3/16 material in one pass. You may also find a stream of air on the leading edge to blow out chips and help cool down the material will help.

Another challenge is to get an even depth of cut (especially with a V type bit) so on our engraver we built a floating head and adjuatable nose piece that sits on top of the material and controls the depth of cut. That makes using air essential to keep the chips from clogging the nosepiece!

TOM caudle
www.CandCNC.com

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