Acrylic engraving help

Hi All

Had my machine for a few months and managed to get my hands on some Acrylic so thought I would test a few things out.

My tool path (in aspire) is a quick engrave at a depth of 0.1mm (tried 0.2 first and that was worse) and outline. I’m using a brand new amana 45771 bit (30 degree 0.005 tip) with feed set to 70 ipm.

I have set my router to 2 on the dial to slow it down but I am still getting some melting/welding of the chips see images below.

So a couple of questions for people more knowledgable than me

I presume the bit is ok to use on acrylic.?
Is my feed to high or to low?
Should the router be at a slow speed or higher speed?

I assume that you are trying to edge light the acrylic. For best results use a diamond spring bit with the router turned off. You can find them on Amazon for ~$50. I use a 90deg RDZ Engraver from United Stamping LLC…

I should add that I have limited experience with V-bits, however I have created some successful edge lit acrylics with a v-bit. It is hard to make lines with the diamond bit. Looking at what you posted, your depth seems too deep. Mine was only .02" deep, with a 60deg vbit. You may not like the width of the line with that depth and a 30deg vbit. Try something shallower, say .05" and see how that looks. Also, my feed rate was 45ipm and 12000rpm on the router.

I have lots of hard-earned acrylic experience. First and foremost, it should be CAST acrylic if you’re using a bit and router. Extruded has melting issues b/c it is formed at a lower temperature. Cast is (usually) paper-backed; extruded is film-backed. Also, there are good YouTube videos on this topic.

@mwaddellus this is Film backed both sides I’m not sure how I can tell if it’s cast or not, as this was an off cut from work.


I will continue to experiment!

@chuckweiser thanks for the help I will try a 60 deg and also vary the depth

If it’s film backed both sides it’s very tricky to mill (or route). There are specific plastic cutting bits - you want O-flute spiral upcut. The upcut pulls chips out of the kerf to reduce re-welding (melting). Onsrud has these bits as well as feeds/speeds.

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Thanks Michael will investigate!