Hi, I think that someone has already shown it but just to share my thoughts with you about that. Rather easy though I had a friend who helped me turning the "wheel" while radiusing the dishes. Alone would heve been more difficult...
From a square
a home-made compas
First ring
And two others (one for a 15 foot radius - back, one for a 28 foot radius - folk top, one for a 25 foot radius - classical top)
Some straight wood on which I trace the radius (the sagita).
on one side 15 foot (on the other 28 foot)
The the Stew machine
Checking out with a cardboard, -7.5mm for 15 foot et -4mm for the 28 foot (for a distance of 52.4cm long)
Then for real with a pin in the center
The 15 foot bars
The using the machine
Careful near the center, so as not to lean with all my weight, though the wood don't bend easily
Then the final check out
Then a fast sandind and varnish to protect
