Joez, Welcome to the Zone.
I went with dual leadscrews on the X of my last machine. It really helped with gantry racking (the left to right twisting). It worked very well for me. I used two motors, but many have a belt between the two with a single motor in the center.
As far as keeping a leadscrew from whipping, a few things I have learned. Keep the pitch low. If you move a farther distance with each revolution, you can keep the rpms down and it won’t whip as much. Conversely you will gain speed with a given rpm, and I keep repeating to people that speed is fun and also needed for routing certain types of media. A fat leadscrew won’t help that much. 1/2" is plenty. A larger diameter will be harder to spin and you will reduce torque. Much better to spend time on mounting the screw to the machine. Use a double bearing on the motor side and a single on the free side. The double bearings should be clamped together against a thrust plate. The free end should be tightened to keep the screw in tension. This will keep the screw taught, reducing whip and backlash, while saving the bushings in your motors.
Look at commercial machines with ballscrews. Their lead pitch is low, their diameter is small(er), and they are correctly mounted.
What kind of linear bearings did you draw? Are those of your own design?
Steve  |