-Pipe, does it matter if it’s schedule 80 or 40? Is one any better than the other for this project?
I wouldn’t guess so as long as the outer diameter is the right size. With the size you’re looking at, the thicker walls seems like it would be a better bet.
-Size, I’ve never seen a clear answer on this and I suspect it’s because pipes that will be holding the weight of the tool head will flex a bit one way or the other depending on your tool and the material being worked. I’d like to use this on wood initially and I’d like to be able to get a full sheet of plywood up to 3/4 inch in there. Has anyone made this size? What are the “gotchas” I need to look out for?
That’s pretty big… here’s the first one in build forum I found that’s pretty close: http://www.vicious1.com/forum/topic/test-run-of-the-7-5-foot-x-4-foot-mpcnc/ Looks like he added an extra set of grantry pipe to make the middle more rigid. Try looking through the build forum for some more.
-I plan to mount it on a large board (which may actually limit me to < 4×8 sheets of plywood) and put it on a system to pulley it off my garage work bench when not in use. Anyone have any experience with moving one of these? or does everyone just mount it directly to a table for the added rigidity?
I saw one a while ago where they put it on a hinge to fold it up against a wall when they weren’t using it. If I remember correctly though, it was more in line with the recommended size.