As most of you know, my first attempt at a CNC machine had a few nice little innovations. Well, I'm in the process of designing a new one to replace it, and have a question.
On many machines on this site (7th sojourn inspired, I think) it looks like the moving table is unrestrained. It simply "sits" on the rails, and is held on by gravity...racking is controlled by a second set of bearings. But, the bottom line is that only gravity holds it on.
My first machine had the bearings located such that I could turn it upside down and the axes would stay in place...but this created a different set of issues...outward thrust and the flexibility of the rails.
In an attempt to further simplify, I'm thinking of running unrestrained rollers over a fully supported track, but with only gravity holding down a moving table. Is this a good solution, in practice? Seems like it should work.
What other issues would it create? Lift from upward spiraling bits, perhaps? Like I said...I did it differently, last time...and I'm just trying to simplify.
-- Chuck Knight  |