I want to build a single rail that has two lead screws in it to allow dual gantry platforms to move up and down the rail independently in either direction. Could this be done on a 20x80 V-slot rail? I have never used these parts and don't have a sense of if there is space, and also if the gantry carts can move smoothly if the attachment to the rail is off-center. I've included a sketch of the system. Thanks for any help!
If you built them so that neither would ever cross the middle, you probably could with existing parts. You would have to probably custom make a couple of parts, but it shouldn't bee too hard. Here is a link to an actuator. C-Beam® Tension XL Linear Actuator Bundle Here is how the parts go together so you can get a better idea. C-Beam® Tension XL Linear Actuator The motors mount in the middle so you would need one on each end. Or, again you would have to make custom parts or use plated like these mounted off to the sides. Threaded Rod Plate - NEMA 23 Stepper Motor
Yes, it's possible. If you need NEMA 23s, a reasonable solution can be found at V-Slot NEMA 23 Linear Actuator (Lead Screw) | OpenBuilds. Shows the basic idea but for your situation the motor mounts will need offset 20mm from the location shown on the 20x80 example and the motors will need to be set at the opposing ends. If you need to keep both motors on the same end, you'll be limited to NEMA 17 motors as shown in V-Slot® NEMA 17 Linear Actuator Bundle (Lead Screw) | OpenBuilds. There are also some interesting alternate concepts shown at the bottom of the page which can be downloaded in SketchUp format via the files and drawings tab higher up on the page.
