Engraving/machining acrylic

**cropwell** · 18-08-2016

I have had reasonable results using lots of air to clear chips and WD40 or Fixt spray to keep the cutter lubricated and cool. A sharp carbide single flute cutter with open architecture (lots of space in the spiral, to allow chips to get out of the way) helps. You also need to make chips that take the heat away, not rub the plastic.

**magicniner** · 19-08-2016

Originally Posted by cropwell

A sharp carbide single flute cutter

+1 to this, also the single flute cutters are easy to sharpen with a little practice.
I made some covers for Theoben airgun magazines in acrylic and flame polished the inside (machined) surface to achieve good transparency,

- Nick

**cropwell** · 19-08-2016

Originally Posted by magicniner

the single flute cutters are easy to sharpen with a little practice. - Nick

Never had one go blunt, had plenty of the feckers snap though!

**andy_con** · 19-08-2016

thanks for all the info

I have a denford micro router, which is enclosed. I did wonder if things in general were getting hot yesterday, it was a hot day and once I closed the door of the router there is no air movement inside.

how small can you get single flute cutters? I want to engrave so didn't want to go any bigger than 1mm really

**A_Camera** · 19-08-2016

Originally Posted by andy_con

thanks for all the info

I have a denford micro router, which is enclosed. I did wonder if things in general were getting hot yesterday, it was a hot day and once I closed the door of the router there is no air movement inside.

Do you have any dust extractor? In my opinion that is VERY important.

Originally Posted by andy_con

how small can you get single flute cutters? I want to engrave so didn't want to go any bigger than 1mm really

The smallest bit I am using is a 0.5mm but it is a dual flute. Feed rate is EXTREMELY critical, run it just a tiny bit faster and it snaps. But... if you are engraving for LED signs then V-bits are better unless you need to engrave large letters or remove a lot of material, because those are more rigid. Never the less, if you run it too fast or too deep you will snap off the tip, especially the tiny 10degree 0.1mm are very sensitive.

**andy_con** · 19-08-2016

yes it has dust extraction which I use.

I'm engraving so v bit would be fine. I have some v bits which I use for engraving on ally, so I could test one of them. ill reduce the speed down also

Originally Posted by A_Camera

Do you have any dust extractor? In my opinion that is VERY important.

The smallest bit I am using is a 0.5mm but it is a dual flute. Feed rate is EXTREMELY critical, run it just a tiny bit faster and it snaps. But... if you are engraving for LED signs then V-bits are better unless you need to engrave large letters or remove a lot of material, because those are more rigid. Never the less, if you run it too fast or too deep you will snap off the tip, especially the tiny 10degree 0.1mm are very sensitive.

**A_Camera** · 19-08-2016

Originally Posted by andy_con

yes it has dust extraction which I use.

I'm engraving so v bit would be fine. I have some v bits which I use for engraving on ally, so I could test one of them. ill reduce the speed down also

Please note that I still don't have my high speed spindle installed om my machine, and my current spindle is maxing at 9000RPM, so perhaps if you spin your V-bits fast enough you can increase feed rate as well. Anyway, 22k RPM and 300mm/min is not a good combo. With 22kRPM I would try at least 6-900mm/min using a 30degree 0.3mm V-bit. You have to watch out for corners, the machine may drop the feed rate speed but the spindle will continue spinning at 22k RPM, so melting can happen when rounding corners and then continue on the straight part or the mass of the melted plastic will snap the tip, whichever comes first.

I think it is easier to master milling and engraving at lower RPM first before speeding up things. Once you know you can do it you at low speeds you can start increasing the speeds and understand better what is going on if something goes wrong.

On a side note... I'd start with a brand new and sharp V-bit because if you use an already used one, especially if used on aluminum, then it might not be as pointy and sharp as needed for plastic. A defective or damaged cutter may cause problems (melting, bad edges, uneven surfaces and so on) or may give you good results which are not valid for a new and sharp one. I think it is best to use good tools, so buy a bunch of those and keep a stock of them. You will need more than one before you are confident enough...

Good luck. Milling and engraving acrylics is fun.

**naijin** · 16-09-2016

Originally Posted by A_Camera

Do you have any dust extractor? In my opinion that is VERY important.

The smallest bit I am using is a 0.5mm but it is a dual flute. Feed rate is EXTREMELY critical, run it just a tiny bit faster and it snaps. But... if you are engraving for LED signs then V-bits are better unless you need to engrave large letters or remove a lot of material, because those are more rigid. Never the less, if you run it too fast or too deep you will snap off the tip, especially the tiny 10degree 0.1mm are very sensitive.

Hi there, I have done about 10 acrylic signs so far, I use a v bit and a 3mm end mill but I only go as high as 7000-9000 rpm and it seem to work ok.

Nick

**andy_con** · 15-10-2016

Thanks for the advice got speeds and feeds perfect

**A_Camera** · 17-10-2016

Originally Posted by naijin

Hi there, I have done about 10 acrylic signs so far, I use a v bit and a 3mm end mill but I only go as high as 7000-9000 rpm and it seem to work ok.

Nick

Yes, that's what I am using as well. Have not tried to run faster yet, but will try soon.