On Fri, 3 Jul 2020 14:29:23 +0100, John Rumm
wrote:

You want the blade on the radius.

Got it. And I have both hollow-ground sawblades and blades with a set, plus
pendulum action, so I can adjust the kerf to suit.

I would make a ply guide say 5" wide
and as long as needed. Stick a hole through the jigsaw end with a spade
bit to allow some clearance round the blade, and then pin and glue
blocking to the ply to trap the base plate of the saw, with the blade
poking through. Then add a screw etc for the centre pin.

Yup, though I may be using sheet metal -- depends on what's kicking around in
the odds & ends corner. And there's two holes in the base, so It'll probably be
just two screws to connect tot he base.

Although I would not drill the start hole such that it leaves a divot
out of the circle!

Aaaargh, and a big one, too. Though in my case, I can make a big divot, 'cause
I'm notching the edge of most circles 22x44mm wide, and can put the divot in the
waste:-)

(Why ever do people show a ten-minute video to show something that would be
self-evident in a drawing that can be grasped in seconds?)


Thomas Prufer