Silvan,

I almost has the same problem when making my insert but I had actually
bought a second factory made dado insert (hey I was a newbie and
needed to get stuff done). Since they were both about 1/8th" think, I
stacked them together with some wood and drilled through the bolt
holes. Just put a screw in the hole and the 2 1/8th" insert became a
1/4". Made for easy routing.

I hate hearing people spending $22 they don't have to. I have a delta
and have a bunch of blanks made out. If you have a delta (i think all
their inserts are a standard size, but I only have had 1) let me know,
I'll mail you a couple.

Chuck