Effect of Forces on Gantry Cross-Sections?

[wilfy]

Ok but mounting rails on 2 smaller pieces of box section is ok I presume because you can make some adjustment??

[Jonathan]

Ok but mounting rails on 2 smaller pieces of box section is ok I presume because you can make some adjustment??

Yes, unless the box section is really bad - for instance if it has been welded it would distort somewhat.

[irving2008]

Ok but mounting rails on 2 smaller pieces of box section is ok I presume because you can make some adjustment??

there are two separate issues - parallelism of the oppsite sides of the box and flatness of each side of the box; neither are guaranteed in the manufacturing process. The flatness issue means you might have to shim the rail to keep it straight when you bolt it down.. even if you have 2 boxes you still have this problem. The only sensible solution is to surface grind or face both sides of the box section to make them flat and parallel.