i have 2 designs i use one is a landing gear cart, i cut the holder arm off and
welded a frame withe them. i use this because it is very stable. i move the bp
around to different work stations so i can have one dirty area for cleaning.
the other is a skate that we use for moving machines in place. we use
c-channel and cut one part of the c- off so it looks like angle iron(but
stronger) we then weld 3 pieces of round stock on the flat side equaly spaced.
you should make the center higher by 1/8 to 1/4. on theround stock i put on
old bearings. you can get them free from an electric motor rebuilder, just ask
for some old bearings.
i buy the landing gear carts for $20 at the surplus places, casters are
worth more than that