Rounding the Outside Edges
First the corners are sawed off at 45 degree angles.
This can be done on the table saw using this overhanging fence.
This roughing stage is finished.
The lower deckle has been partially rounded over with a router. One more fine cut will take off the last rough saw marks.
This is how the edges are rounded.
After the outside edges are rounded the front and back need to be chamfered to narrow the inner edge.
Roughing the Chamfer on the Inside Edges
Most deckles have chamfered areas along the front and back (long) sides. The inside edges of the deckle are narrowed to roughly correspond to the desired thickness of pulp to be collected on the mould. One way to rough out the wood is with this panel cutting bit. A spokeshave can be used later to smooth the angular surfaces into a gentle curve.
Rounding the Deckle Rim
The inner edges of the deckle rim need to be rounded off so they don’t catch on the mould’s copper edge strip as the deckle is taken off the mould.
I do this by hand using this burred scraper. It’s the blade of the scraper plane that was used earlier to level the ribs.
First an even bevel is scraped the full length of each side.
The bevel is refined into a curve with the scraper then smoothed with sandpaper.
These last two photos may show the process more clearly.
Timothy Moore Bookbinding Tools 