The proper answer is 'buy or borrow a table saw with a dado blade'.

However, I don't want to.

I want to use my plunge router to place a 3-1/2" square lap joint
about 3/4" deep on the ends of several pressure treated 2x4s.
I will don a respirator first, no worries.

I've designed an machined jig to allow me to do
this but I want to know how you pro's would approach this
challenge before I search my junk pile for parts.

My Google-fu was not up to the challenge. Instead, it revealed
some table saw adapters.

My band saw refuses to cut anywhere near straight so that's out.

First prize answer would be an inexpensive jig I could pick up
at my local hardware store.

What would SuperWoodworker do?

Thanks!

--Winston


--

Harley was venal, arrogant, despicable and a psychologist.
He was the second most redundant man I ever talked to.