In article ,
William Bagwell wrote:

Need shallow grooves in wood, *lots* of shallow grooves in lots of wood. At
least 48 in each side of dozens of 16 X 24" pieces of plywood and almost as
many boards grooved on only one side.

Remote possibility this will become a recurring need
^^^^^^
For now I'm doing a limited run of prototypes and could resort to cutting them one by one with a
circular saw. Perhaps even two at a time with two blades in a table saw. But
where is the fun in that?

Have access to an old 6" jointer and think modifying the knives with a series
of flats leaving a row of cutting tips spaced approximately 1/2" apart *might*
just work. Cutting at least 12 grooves in one pass.

Router or circular/table saw and step fence (ie, a fence that registers
on the last groove) will do it faster than you can get done grinding
expensive planer/jointer blades into castellated groove-cutters. That's
a pricey way to have "fun", and you'll also have issues cutting these
dozens of grooves much further than 6" from the edge of the board with a
typical jointer fence setup. I infer that this will leave you with about
12" in the middle un-grooved, since it sounds like you are cutting them
every 1/2" in the 24" direction. That's not a good (safe) direction to
feed a jointer a piece of wood, and kludging up a fence that will get
over another 6" will be a major project.

Address the _remote_ possibility when and if it becomes real. I'd just
drop them into the CNC router and tell it to get cutting (and that's
what I'd suggest if you look to production tooling - something flexible
that can work unattended), but with a production-line mindset and simple
fence/jigs it will be done before you'd have the jointer kludged into
doing it.

Dado set without the chippers and a sled with the registration on the
tablesaw is probably most efficient.

Or switch to rough-cut lumber rather than plywood and you don't even
need grooves...

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