If you don't want to cut all the way through your blank extend your table miter guide on the sled and make it twice the thickness on the underside such that the guide hits the edge of the table and stops the sled from sliding further into the blade. I did this to a sled and it leaves just over 1/16" of the blank solid so that there is no shifting when the insert is glued in.
If you want to get real tricky cut a set of spacers that are uniform in thickness of about 1/4 to 1/2". If you put one of them between the end of your blank and the end of the slide where it rest when clamped you can do multiple cuts with out changing anything on your setup. You need to be gentle so the sliver between cuts is not damaged but this way you can make two cuts at the same time. Glue up two inserts at once and get the blanks done with a double Celtic knot in the same time. Plus the spacing is always the same from side to side. A nice touch and easy to do.
When I use my table saw to make Celtic knot blanks I use a set of spacers and can cut double, triple up to seven knots in a single blank. Celtic knots with precision. My Cigar blanks for one piece Cigar pens end up with seven Celtic knots going from end to end. A easy job if you use spacers instead of resetting you sled seven times. I cut all seven on a side, glue in the inserts cure 24 hours, trim flush and do the opposite side. working with ten blanks at a time it goes fairly quickly and when finished ten blanks last me for a lot of turnings. In four nights I have a very impressive, complex blank which would take me several weeks to do otherwise. And somewhere in that weeks time there would be some slippage in the setup. My setup works perfectly every time as longs as the blank is square, as long as I put it into the sled the right direction and put the spacers in order the same every time. I have them numbered 1-8 but never got to use number 8 yet.
