On 4/26/2010 10:09 AM, Winston wrote:
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!

Machined jig?!?!?!?!

Clamp the 2x4s side by side. Clamp a scrap across them an appropriate
distance from the cut line as a fence. Clamp another 2x4 crosswise
along the ends for the router to ride on at the ends of the cut. Route
until done.

If this is difficult for you to set up you don't have enough clamps or
don't have the right kind of clamps. And nobody _ever_ has enough
clamps so go get some clamps if you need to.




--Winston