I had a couple of y-belt-clamps that I made earlier split. It appears that the MDF is a layered material and the way I cut it destroyed much of its strength. I decided to remake all 4 y-belt-clamps with the board oriented differently. I started with 25 mm x 25 mm blocks that were 3/4″ thick. This is much thicker than needed, but I don’t have a safe way to cut pieces this small.
First I drew a centerline (12.5 mm) on each block. Then I drew two perpendicular lines at 6 mm and 19 mm from a side. I drilled two holes where these lines intersected. I drilled them with a 5.4 mm bit all the way through the block.
After that, I drilled two more holes in the same spot, but with a larger bit. I set the drill press to stop 4mm from the bottom of the block. I used a 3/8 inch bit. This was just large enough that I could fit a washer into. Slightly larger would have been better, but the next largest bit I had was 1/2 inch and I didn’t want it that large.
I had to use a screw and nut to force the washers to the bottom of the hole. Once there, they are permanently stuck in the block.
