Originally Posted by JRems
If you have the harbor freight conduit punch set, I used the second to largest one for the electric element, I think it's a 1". The 1/2" works great for ball valves, makes a perfect 7/8" hole. I also used the 3/4 to punch the perfect size hole for the pump outlets like you have above. I guess conduit punches and chassis punches are different size.
Harbor Freight punch sets are "Electrical Conduit Punches" & punch a hole for the conduit fitting.
Here are the stated sizes and the actual hole size: Die - Actual Hole
1/2" = 7/8"
3/4" = 1-3/32"
1" = 1-11/32"
1-1/4" = 1-11/16"
So, with that stated, be very careful.