Cutting .25 thick plexiglass for a guitar body template, using 1/8" 2 flute bit and the CC Pro recommends, 20,000 RPM, and feed at 90.0, at .030 depth per pass. I am testing these settings and others settings, but it still melts the plastic and the shavings stick to it… I am wondering if the bit (an old bit) is dull and if that can be and issue. Or do I need a specific type of bit.
20000 is way too fast. Try 10000-12000
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First consideration — is this cast (paper covering) or cast (thin plastic film)?
Cast mills/cuts well, while extruded is a nightmare.
See:
and consider single flute tooling, or a tool w/ a geometry optimized for plastic.
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Here is the speeds on my Router…I have tried the lowest setting…it still melts and sticks
and a screen shot of what CC Pro recommends.
I run a 1/4" O-flute at 8000 RPM (My slowest speed).
You can try 16000 and increase the feedrate. A single flute cutter may help as well.
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The plexiglass I bought, a 24"x 24" piece had a plastic film on both sides, which I removed before testing. Im not sure if that is what you are referring to.
There are two ways to make sheets of plexiglass:
- casting
- extruding
The former yields stock which cuts well, while the latter is quite difficult to cut.
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I will purchase a sheet of Cast Plexi…and look into a more appropriate bit…thanks…
On CC you have a choice between hard plastic and soft plastic. I am using the settings for soft plastic.
Regarding “MaterialMonday” Videos I don’t recall any reference to which type of plexiglass, cast or extruded.
Plexiglass is acrylic, see the entry for “Cast acrylic”.
Moreover, consider single-flute tooling — there’s at least one video on that there.
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I bought a sheet of Cast Acrylic and did a small test, using the speed and feed settings on CC for hard plastic and the results were very bad. During the test it making all kinds of noise popping and cracking, melted really bad and stuck to the bits. I was using…a single flute 1/8. Perhaps this was not really cast? or maybe I should have used the soft plastic setting in CC which are much faster??
I think all of the speeds (RPMs) for hard plastic are too fast. I use 8000 for 1/4 O-flute, and 10000 for 1/8", and try to keep the feedrates up around 60 or greater. Then it’s just a matter of adjusting the chip volume to something the tool can handle.
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That looks like the problems I’ve had when cutting extruded acrylic, moreover, that description admits of the possibility of using cast acrylic as a source material for extrusion.
As noted, what has worked for me:
- sourcing cast acrylic
- using single flute tooling
- Carbide Create defaults
Some folks have found that an application of dishwasher detergent to the surface helps.
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didn’t think of that… brilliant!!
I’ve used tap magic, which involves adding the detergent to wash it off afterward.
I usually clean my tools with tap-magic & a toothbrush before cutting, and that little bit of lube on the tool helps.
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