What Size Aluminum To Use In Frame?

[thomasholley]

I want to build a small/medium size CNC machine to do things like engraving and cutting in material like aluminum and brass. Nothing too thick, maybe 1/8" max. Right now I know next to nothing and am gathering information to formulate some plans. For starters I think :

Gantry type setup with maximum demensions of about 24" x 36" x and y and maybe 6" for z. I would like to use aluminum for the frame. How thick should the stock be for a set up like this? I have looked at quite a few sites but there is not much data on this (or maybe I am just looking in the wrong places).

Thomas

[wjbzone]

Thomas,
My machine is about that size and rigid enough to make cuts like that. (X 24 Y 13 Z 7) I posted detailed designs of the major components (all made from aluminum) on my website.
www.wjbzone.com
Bill

[stewi]

Nice design, Bill.
Thomas, consider that you don't need much more motor power to move a heavy weight in X and Y. However, weight makes likely a stiffer machine, when you mill aluminum and brass.
If you like to use the aluminum extrusions from 20/20 or Bosch Rexroth, than I would fill the open spaces with MDF or thick plywood just to increase the weight and get the gantry stiff.
I designed a low cost CNC machine myself www.steering-inc.com
It does a good job in wood using up to 1/2" router bit and engraves in aluminum and brass with a 1/8" bit.
Regards,
Stefan