1220 × 2440 build

[JAZZCNC]

Hi Mark
I’ve just finished building an 8x4 CNC. It works ok,
I fitted it with 25mm ball screws on x and y axis and fitted a ready made z axis. The guys above were correct about ball screws whipping or wobbling while running, the y axis is fine, but the x axis has vibration issues. I’m planning on changing the x axis drive to rack and pinion which I’ll be buying from America ready made, I would recommend if your building a machine to avoid ball screws over 1500mm like one of the other guys said.

Hi Malcolm,

I wouldn't do that to be honest because R&P comes with it's own issues and I'm guessing you mean CNCrouter parts R&P which isn't the best thing in world. Ballscrews can work fine if done correctly.
The trick is to get the screw speed down. So to do this you use pitch that is higher than you need and apply a ratio. I'll guess you used 10mm pitch.?
If you had used 25mm pitch then applied 2:1 ratio you would half your screw speed. The ratio makes it the same as if having 12.5mm pitch so you have little more travel speed still with decent resolution. The ratio also increases your torque so little more grunt.

If you use Fixed end bearings both ends of screw and put under slight tension then you won't have any issues. If you watch the video of the Vertical machine it's using 2525 screws done this way and traveling at 15Mtr/min. In testing I had it upto 25mtr/min and still with little left.