Sometimes I need to cut sheets (cca 50x80cm = 20x32") of soft 4mm (1/8") poplar plywood into smaller rectangular pieces and I find it surprisingly difficult to do with hand tools - it's too soft and thin for most saws, but it's too thick for a knife.
Currently, for most cuts I do:
- shallow line with a marking knife using ruler or a square
- follow the line "freehand" with chip carving knife to make it deeper
- repeat heavier cuts with chip carving knife until it's done (it usualy takes 3-5 cuts)
But it's very tedious process which also leads to heavy damage to cutting surface and I have to be very careful to stay in the marked line while applying quite a lot of pressure on the knife. Also the knife must be VERY sharp, otherwise I get jagged edge with chipped out pieces.
For smaller pieces needing more precise cuts I use small 24 tpi saw (Zona). Which is also slow and usable only for really short cuts (no more than 15cm / 6").
I can't use heavier saws because anything less than 24tpi destroys the edge badly.
Is there a better way/tool to do it? (I'm only interested in hand tools)