[mrmummert]

For the past two years 1610 has used the nylon slides that are used with
20x20 and 30x30 extruded aluminium. In 2011 we made end bolted on bumpers
as normal, but for the sides we mounted four slides on the back of the bumpers
so they could just be slid to the side
off the frame. When the end bumpers were in place they kept the side bumpers
from sliding out. We had to counter sink the slides for the screws and slightly
route out the plywood so the bumper was flush with the frame.

This past season (2012) we modified that design. In stead of sliding them
horizontally we modified our frame for 30x30 vertical uprights with
horizontal 30x30 between them (this was mounted on one horizontal 30x30 piece
on the bottom.)so they could be slid vertically. We mounted
a nylon slide on each end and one in the center. It takes a little trial and
error to get them placed right so the bumper comes out the height you want.
We tapped the top end of the vertical 30x30s of the frame to accept a 5/16x 1" bolt.
We'd slide the bumper on,place
a washer on the 30x30 and bolt them down. We could change a complete set
off and on in two mins. Using this design made it a little harder to make the frame
but it saved a ton of time changing the bumpers.