For these clamps, you will need 4 pieces of stock. I have upgraded from standard 2×4 stock because I found that it wasn’t rugged enough for the abuse.
I have chosen Live Oak for my upgrade but any hardwood will probably work as well. Preferred species would be Hard Maple, Hickory or Ash.
My stock is 2 inches wide, the top piece is 1 1/8″ thick and the bottom is 1 1/4″. The top dimension thickness is so that my minimum cut thickness is 4/4 stock. The bottom clamp piece thickness dimension is not important but will determine the length of your bolts.
Sequence of Operations:
When drilling the recesses for the bolt heads, drill the recess first then the through hole. You can drill the minor diameter (measured across the flats of the bolt head) of the bolt head and then chisel out the flat areas or set the bolt heads in Epoxy. I have chosen to keep the bolts loose in their mountings in case the clamp slips and digs into the bolt ( I can easily replace the bolt but I still have a dull chain to deal with).
Once the holes are drilled then recess the underside of the top clamp piece. Alternatively, you can glue a thin piece onto the center of the clamp ( I would use Epoxy for strength). But remember to adjust the thickness dimension if you do this.
When you are finished making the clamps add a small piece of rubber to the inside of both clamps. This will keep the saw blade from scratching and provide more friction for the clamps ( I cut a piece off a Rubbermaid glove but rubber shelf liner works well too).
You will want to make another recess in the bottom of the guide board for the top nut (Under the guide board on top of the clamp or spacers if they are used) on the threaded rod. This can be drilled out at 7/8″ or larger as the nut will need to be tightened and may end up in a different orientation each time it is tightened. A spade bit will work well for this. Insert a temporary plug into the 3/8 inch hole if you have already drilled it to keep the center of the bit tracking well.