How to efficiently trim 3mm polycarbonate with portable tool(s)

cuttinghand-toolssanding

I have a square of 3mm thick polycarbonate (aka "Lexan" after a common brand, though mine is a different brand) that is roughly 50cm along each edge.

I need to trim a few mm off one corner and part of one side, as viewed from the front, in order to fit this polycarbonate into an aperture that is not quite square:

         ~5mm ↴
              ↔
|------------\--|  ↑
|             \ |
|              \|
|               | 50cm
|               |
|               |
|---------------|  ↓
 ←    50cm     →

(Diagram not to scale.)

I tried using a small surform, but although my surform is sharp enough to work well on wood, it makes very slow progress in this polycarbonate sheet. Coarse sandpaper also makes very slow progress.

I am thinking of using a tenon saw to cut off the corner concerned, but I am concerned about cracking or otherwise irreparably damaging the sheet.

Bench tools aren't an option, unfortunately, both because they aren't available on-site, and because there wouldn't be room to deploy them even if they were available.

Question: does the tenon saw sound like a good bet, or is there a better tool to use? Either way, should I do any specific prep, such as applying masking tape where I will be cutting, to reduce splintering?

Best Answer

If you have to use an unpowered hand tool, then a file or possibly a hacksaw will work. Anything with coarser teeth than that (like the saw you linked to) will be very difficult to use on such a hard material and cracking is likely.

If you can use power, a belt sander will work. An angle grinder iwth a cut-off wheel or Dremel tool will also work, but they can be a hassle to use if you have a long cut because they cut slowly and stink because they melt the material as they go (use in a well ventilated area).

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