Eliminate Tearout Routing Plywood
A square wooden edge can hurt people, and it can collect dings. So it’s a good idea to “soften” it. Generally, that’s done with a router. With plywood, though, large chunks can tear out at the end of a cut. But there’s a fix!
High-Quality Plywood is a Must
You have to start with a good quality “cabinet grade” plywood, of course. Even then, you’ll often have some voids to fill after rounding. That much comes with the territory. There won’t be as many as you would get with a lower grade, and they won’t be as large, but there will still be done.
Baltic Birch used to be my go-to choice, until brother Putin decided to shoot his entire country in its collective foot. Baltic Birch is produced in Finland, as well as Russia, but everything Finland makes they can sell in Europe. So that once-stellar option is no longer available. The best alternative I’ve found so far is Poplar plywood. It’s not quite as good, but it’s been a reasonable substitute.
Bamboo plywood may also be a good choice. I don’t much like the edges for my benches, but some do!
Solving the Blowout Problem
The problem with roundovers and chamfers on plywood is the blowout that can happen at the end of your cut, no matter what grade of plywood you’re using. But there are solutions!
- For the narrow edge of plywood, rout last, or don’t rout at all.
The standard advice for roundovers is to do the shorter edges first. Rounding the longer edges will then cover over any breaks that occurred on the short edges. That may work for standard lumber.
It doesn’t work for plywood.
At the end of a rounding pass, plywood can tear out a splinter that’s too big to cover up with the next cut. To minimize the chances of tearout, round the narrow edges last, after the “points” have been rounded.
(For panels, there are “faces” and “edges”. Where two edges meet, that’s a corner. Where a face and two edges meet, I call that a point. (Someday,
I’ll find a good name for the meeting of a face and an edge. Calling it a “corner” or an “edge” just invites confusion!)
After rounding the top and bottom of both faces, all the way around, the points…