Quote Originally Posted by Zeeflyboy View Post
Interesting. Just to be clear the part of the gantry that is actually doing the work is 65 x 200 mm made up of a heavy 40mm extrusion and a 25mm tooling plate, not just the 25mm tooling plate on it's own. The span is 620mm... it also has 6mm plate top and bottom which will be screwed down to the extrusion and the tooling plate. Given the relatively short span I don't think it should have much flex?
The 25mm plate may not stiffen much the alu profile. The top and bottom 6mm plates probably won't do anything. Each bolted joint is a potential weak link when the contact surfaces aren't perfect.

Now all we are doing here is guessing. A very stiff gantry won't be very useful if the weakest link is your gantry arms.