Cutting polystyrene with Makita

[cff]

I purchased some polystyrene moulding because it is available in my area and it was really cheap. But of course I am having issues cutting it.
I've been doing some internet research an came up with a couple of suggestions:
- Cut fast with blade of 80 teeth or more.
- Cut fast with blade of 35 teeth or less.

So I did both. I have a 10" 80 teeth blade on the Makita and did a fast cut with it. It gives me melting and really bad cuts (Photo attached). I've also tried with a 24 teeth blade with similar result.

Does anyone have any suggestions of how to proceed?

IMG_2391.JPG.jpeg (73.28 KiB) Viewed 3631 times

Jamuna

[Roboframer]

I'd say you need a mitre guillotine that does not generate the heat that a circular saw does.

[prospero]

I have heard tell that you need a blade with negative rake teeth for sawing poly. Not tried one though.

[cff]

What is negative rake teeth?

[prospero]

[cff]

Thanks for the video. I'm now wondering if I need more teeth or less teeth with a negative hook blade for cutting polystyrene.

[China shop]

80 teeth or more, negative rake and cut across fairly fast, that should do it. Cutting across slowly will melt it.

Also the quality of the moulding will have a great impact on the quality of cut.

[cff]

Thanks so much for the input. I will try some things and post the results.

[Graysalchemy]

I cut plastic mouldings on my Cassese 939 and use the same blades as what I use for wood. A faster cut and more teeth is what you want. My 300mm blades have 100 teeth in a positive rake. You will get some burrs as the plastic is cut and it melts. I presume your blades are not 300mm, are you cutting with a vertical action or a sliding action? The Cassese saws cut with a sliding action and it is the speed of the slide which makes the difference.