Need Help!- Cutting Mirror Acrylic (Extruded)

[dttechnician]

Hi there. But of a newbie here.

I am a technician in a UK Secondary School and we have a Roland TS30 machine.

We alwas cut Cast Acrylic on it but we are looking at a project where we'd like to make shaped mirrors. I can only find Extruded Mirror Acrylic and whenever we cut Extruded material they swarf that comes off then melts and binds to the tool.

Does anyone have any tips or tricks that I could use or is there a certain way of cutting.

We generally use a 2mm slot drill and the tool spins at 10000rpm and we use a cut depth of betweeen 0.5mm to 0.75mm per pass on a 10mm/s feed rate.

Thanks in advance.

[RomanLini]

Sounds like your RPM is too high and feed is a little slow. You also didn't say how many flutes on your 2mm endmill?

I haven't had good results with a 2mm tool, they tend to flex a bit and that ends up with heat and melt problems as a result. They also blunt too quickly (again more melt).

I would suggest 3mm or 1/8" endmill, 0.5mm depth, maybe 8000 RPM and similar feedrate. Some people use a hand spray mister with the occasional mist of water or water with a couple drops detergent, or maybe a steady blast of compressed air to clear the chips and cool the tool.

And a NEW sharp tool that has not been blunted by the blunt students yet...

[dttechnician]

Thanks for the reply.

The 2mm bits we use have 2 flutes. We buy them from Techsoft here (Scroll down to Slot Drills).

So I should be try 8000rpm with a feed rate of 15mm/s with a depth of .5mm per pass?

I'll order a 3mm bit and have a go with some scrap extruded.

[millnturn]

I have had good luck with single flute end mills like these: http://www.harveytool.com/products/p...ting+End+Mills

I second the advice to use a light mist of water. Also, a pneumatic cold air gun really helps when directed right at the action. http://itwvortec.thomasnet.com/viewi...gun?&forward=1

[dttechnician]

Well, whilst waiting for the 3mm slot drill to arrive I did have a go at cuting through a scrap piece of extruded acrylic that I had lying around.

I set up using 8000rpm and feed rates of 15mm/s with a depth of cut at 0.5mm per pass.

I'm happy to report that I didn't get any binding around the drill head.

I'm also planning on having a go with cutting a shape about .25 - .5mm away from the outside edge of my shape so that I can use a finish cut to give a nice smooth edge.

Thanks for the suggestions so far.