[MrForbes]

We haven't really standardized on any particular size of hardware, because different things need different sized hardware. For example, mounting SMC solenoid valves requires 2-56 hardware, while mounting one end of our roller uses 1/2-13 hardware. We use several different sizes in between, too....5/16-18 for bumper mounts, 1/4-20 for several things, lots of #6, #8, and #10 screws to attach stuff to the plywood belly pan....and rivets in 1/8, 5/32 and 3/16" sizes of various lengths.