x-axis rails and lead screw

[adambrum]

Just a quick question

Im finally getting around to building a router but im not sure on the size of the supported rails and leadscrew.

I will be mainly cutting acrylic and alloy and teh design thats in my head should be very stable.

So would 20mm supported rails be ok for a 48" axis with a 20mm ballscrew, originally i was going to go for 16mm all round for the leadscrews but i think the 20mm may give me less whip at higher speeds.

Thanks Adam

[E.V. MacHine]

Hi Adam,

I think you're probably about right - I'm planning something similar, myself. No reason for not using bigger rails (25mm?) on the long axis, as they're not moving, but lighter for the gantry, of course; supported: definitely - can't see the point of doing it any other way - and why not just make them structural as well?

As for ball-screws, thinner limits the revs for whip, but thicker makes for greater inertia, i.e. limits acceleration, so it's a compromise (there was a discussion about this - with diameters/lengths and revs., on another thread, somewhere). But it all wants to be as concentric as possible, no obvious run-out or mis-alignment, good bearings; and well-balanced. Vibration analysis would be a Good Thing, if you can find someone to do it... (optional !-) Only just spotted your query, I'm new, too. Hope it helps.