What he's saying is if you push on the side of the gantry uprights, the 3/4" MDF will flex and the gantry will move from side to side. By at least doubling them up, it will be stiffer. I'm making mine out of 2 pieces of 5/8 MDF, with a 1/2" Hardwood frame in between them. I also epoxied a 3/4" x 3/4" Aluminum tube running from top to bottom, in a rabbit down the center. You want them to resist flexing in all directions.
Not sure how tall the uprights are, but I'd use 2 bearings on the bottom rail, about 12" from outside to outside. A single bearing will probably have binding or sticking issues.
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Gerry
Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management) |