On Thursday, 2 July 2020 13:41:41 UTC+1, Thomas Prufer wrote:
Given: plywood, jigsaw
wanted: circular bit of plywood, diameters 60-80 cm, small hole in the middle is
OK.

Yeah: "make a jig", i.e. an arm with the wanted radius, attached to the jigsaw
base, screw middle down and cut around.

But: I seem to recall there's a catch there somewhere, or a best way of doing
this, in positioning the radius arm with respect to the blade. Should the radius
arm attach to the jigsaw a) ahead of the blade, b) exactly off to the side of
the blade, or c) further back from the jigsaw blade?


Thomas Prufer

A jigsaw is not what I'd recommend, they often wander all over the place & require endless steering to get back on track. There are various other ways depending on exactly what you have. One possible is to saw it a little outside the line, mount the disc in a drill & hold coarse sandpaper upto it to sand it as it spins. Not too fast

A more suitable power tool would be better, but this approach would get you ther.e


NT