• Linear Motion Tradeoffs

    06/30/2022 at 02:28 0 comments

    In thinking about and designing 3d printers, cnc machines, and random robotics things, I always seem to come back to motion systems. Usually linear motion systems. I can find a lot of subjective things like "ball screws are better than lead screws, and linear rails are better than v-wheels," but by how much? In what specific ways? And is that even true, or just false knowledge passed down by people repeating what they have heard?

    As far as I can see it, there are two separate parts of a linear motion system: the drive, and the support. And there are a large number of measurements where some combination of systems may excel or fail.

    Drive Systems (in no particular order)

    • Rack and Pinion
    • Chain and Sprocket
    • Timing Belt
    • Lead Screw
    • Ball Screw
    • Solenoid
    • Maybe others?

    Support (in no particular order)

    • Linear Rail
    • Lead Screw
    • Ball Screw
    • Linear Rod
    • V-Wheels
    • Conveyor Belt-style-thing
    • Probably many others I am not thinking of

    Objective Measurements

    • Maintenance Required (oiling, etc.)
    • Maximum Load
    • Maximum Distance
    • Speed
    • Backdriveability
    • Noise
    • Inertia
    • Friction
    • Vibration
    • Backlash
    • Initial Setup (belt tensioning, for example, other methods of setting preload)
    • Differences per axis (for instance, my gut says lead screws can use gravity as a form of pre-tension, meaning they probably inherently work better as a z-axis)
    • Probably others

    I would love it if there was a list somewhere where someone has done the research and laid out in fairly objective ways the pros and cons of the different combinations. I haven't been able to find anything though.