DO. NOT. USE. BLADES. TO. CUT. PLASTIC.
at least not anything thicker than 0.2 mm or so.
Coloured plastic is easier to cut than clear (for any given thickness).
Use a fine toothed saw instead.
This is called a coping saw (just one example):
The fret saw is even better at cutting curves but is more sensitive so it takes some practice to use. The bow acts like a spring pulling the blade straight. The blade can be inserted through a 1.5 mm hole (some blades are thinner than others) and then attached to the other side of the bow. The saw cut can therefore be started inside the material.
Fairly easy to make. It is very useful if the clamp does not protrude above the board.
There is also the jewelers saw which can reuse broken fret saw blades (they do break from careless handling, been there done that)
Fret saw blades exist for wood/plastic and for metal with diffeent tooth size.
Working too fast in plastic will melt the plastic and make the blade stick (it will break) so work slowly (also aids precision). Cut slightly too wide in the
beginning and file/sand down to proper size.
Further reading:
The fret saw can also be used to remove parts from sprues when side cutters can’t reach OR the sideways force from side cutters could damage the part. Indy-link tracks with multiple sprue gates for instance.
Why not? Don’t try to cut through in one go if it’s thicker than a quarter of a millimetre or so, but other than that, you can get through any reasonably thickness with a knife by making enough passes. And once you get around halfway through, you can also snap the plastic along the seam, if it’s rigid enough to allow that (usually from around 0.75 mm on up).
Of course, as soon as you get thicknesses of over about a millimetre, cutting with a knife will get tedious, as well as more difficult because the material will grab the blade. A saw is a good tool at that point, or a plastic scriber like this:
This is an Olfa one, but the exact same ones are also sold under Tamiya’s brand name. Anyway, these are used the same way: multiple passes to get through. This because they don’t cut the plastic but pull a sliver out of it:
In some ways, I suppose. It has the same advantage over a knife that a saw does, anyway: it removes material instead of pushing it to the side. However, because it cuts a groove, you will generally have to sand, scrape or file the edge you cut in order to make it square. This is much like when you cut plastic card with a knife, though, except with that you need to scrape or file down the surface of the material along the cut, rather than the side, if it’s to be properly flat.
I use a very small piece of mounting putty/blue tack.
