Definately a scrapyard challenge

[Jonathan]

C section also does not have very good rotational stiffness. If you added another bit on the back that would make an I, better but still adding some rectangular on the back (100*50, or over 100) would make a big difference. 1/4" looks a bit thin to be mounting the rails on.

Two pieces of box section wide enough for the rails on a flat aluminium plate with the rails facing outwards is probably the simplest.

[m.marino]

Bruce,

Another option you could look at with that build is two section of rectangular box section and bolt a backing plate or wings to them and bolt that to the gantry uprights as well as the box sections themselves. This will give a good bit more rigidity and either the wings or the backing plate could be indexed to help keep it all true and proper. Drop me a message and I can send you a few files in a format that you can use of ideas Jazz and I worked on that will work. Also take a look at my build log as there are some ideas in there you might be able to use. The following might help:

http://www.mycncuk.com/forums/showth...-machine/page6

If you scroll down you will see one model with sections lifted off to show an idea for the Y axis. That might be a good place to start from and change the solid rail to box or rectangular section extruded aluminium or steel and you would have something that would be a good bit more rigid then the channel. Just trying to help and hope not to offend.

Michael