CNC design for consideration

[jonbabbz]

So what spacing would you suggest Jonathan? It's a valid point but I would have thought any forces trying to twist it on the y axis would be counteracted by the bearing diagonally opposite as it is. Obviously bigger spacing would make it more durable, but I can't widen the actual machine any more as I already have my screws and rails. I guess I'll just have to sacrifice travel on y.

[blackburn mark]

So what spacing would you suggest Jonathan? It's a valid point but I would have thought any forces trying to twist it on the y axis would be counteracted by the bearing diagonally opposite as it is. Obviously bigger spacing would make it more durable, but I can't widen the actual machine any more as I already have my screws and rails. I guess I'll just have to sacrifice travel on y.

i would at least try to fit them flush with those side plates... the tool deflection forces are not your main worry, what would worry me is resonance
if the resonance from cutting finds the sweat spot on your Z the forces will be masive compared to the cutting force and will result in a crap finish
it may only take a little extra stiffness in a design to prevent your typical router resonance getting a grip.... so in my opinion, every tiny little bit of stiffness you can squeeze out of the bugger will pay


imagine you push on a lamp post... your not going to cause it any mischeif... then you push and pull the lamp post with the same force in a opportune rhythm you can get close to wrecking it... with this in mind the problem becomes a little more stark

in an ideal world i guess you would space your bearings at least as wide as you have them tall and if not, as wide as you can