Step 3: Drill mounting holes in the yoke
Put the chuck end of a 3/8 inch twist drill through the hole in one of the strap iron pieces. Insert the same end of the bit into the crosscut indexing hole on the yoke. Press the strap iron down on the yoke surface and turn it so the flat side of the strap iron is parallel to the side of the yoke. Carefully mark the centers of the 1/4 inch holes for drilling holes in the yoke.
Drill holes straight down through the yoke. The holes should be correctly sized for a 10-32 thread tap. Tap threads in the holes. (The drawing shows the holes you will drill. Note the black dots on either side of the indexing holes for the crosscut and inrip positions.)
Place a lock washer onto a roundhead 10-32 screw and thread it up from the underside of the yoke. Tighten it. Do the same with another screw in the other hole. Put a 10-32 nut onto each screw, but do not tighten the strap iron plate down too firmly, yet. Grind or otherwise cut the length of the 10-32 screws so their ends are flush with the top of the nut.
Repeat the process in the previous three paragraphs for the inrip hole and its strap iron plate.