"Mike Pio" wrote:

I couldn't possibly run the saw this way to get the slot started.

I had the same problem with my saw (a General 650), where the blade can be
lowered just a little more than 1/4" below the surface, but not the full
1/2" required. I do not (yet) own a dado or a smaller blade....

So to make mine, I used a 1/4" straight bit in the router, set to 1/4"
depth, and used an edge guide set so the cut groove is the where the blade
will be. If you don't have an edge guide, use whatever method you like to
cut measured straight grooves. Make the groove extend about 4" front and
back of blade center. This will leave 1/4" of material to host the zero
clearance slot.

I could now lock down the insert sitting flush before raising the saw blade
through it.(again, this requires that the blade be lowered at least 1/4"
below table surface).

As an added benefit (YMMV), the sides of the insert's zero clearance slot
are now only 1/4" deep, rather than 1/2", which means less noise, and I
would think less wear on the sides of the blade's teeth.

/rick.