I am interested in the idea of using a Non-Captive Linear Nema 23 stepper with a long 8mm TR8*8-2p Acme screw (Standard OB) for long actuators/machine axis. With Non-Captive Steppers the Stepper motor moves along the Screw, the Screw is stationary, since the screw does not move or rotate, it is not prone to screw whip and longer screws can be used (1500mm+) to create much larger machines then commonly available with Screw motion Would appreciate thoughts and comments about this idea,
Should work great, would love to see it! Two issues Have you found a supplier with longer leads? all I can find are 2mm lead screws, this would make the movement slow. Openbuilds screws for example are 8mm lead (4 start 2mm pitch) second, when the nut wears out you will need to replace the whole motor unless they have serviceable nut, which I have not seen in Nema23 size. Cheers Gary
Rotating-nut builds are semi-common in long-travel screw-based machines where rack and pinion isn't an option for whatever reason- accuracy, typically, though torque at speed and holding power could also be issues. I used one on my laser z-axis for design optimization, and plan to use one on an upcoming ballscrew build for the longest (1500mm) axis to avoid screw whip, since it should be a fairly high speed machine. It also allows you to tension your screws more than you typically would be able to without binding in a traditional rotating-screw setup. Since mine's purely for positioning, gravity provides all the anti-backlash I need. Obviously on a mill it wouldn't be that simple.
