Yes, but you can use couple of finishing nails or grip bolts to hold them in the tray and then clamp them with the 2.5 bridge. they may be off by a fraction of a mm, but no big deal. Be careful to keep the support triangles in the exact same position when you zero it and when you're balancing the blades-- if you let the supports move, it throws off the zero point and you won't get them balanced correctly. I drew datum lines on the surface of my bench to line them up with, but eventually I'm going to get motivated and make a shaft for my TopFlite magnetic balancer so I can use it instead.