Using the rack for calf lifts

I'm still adjusting the power rack configuration for my calf exercise. Here's what I'm doing now.

The basic idea of the lift is to have the bar on my shoulders with my toes supported on the top of of a 4 x 4 inch block with my heels unsupported. I then raise and lower my heels using calves alone.

The rack is setup so the bar rests on the crossbeam below the bottom of the lift. The bar slides up and down the side of two 2 x 4 inch pine blocks located on each crossbeam as shown in the figure. Using the block avoids irritiating bumps that would otherwise be caused when the bar hits the top of the beam slider.