The “goto” zero backlash gearbox for hobbyists is normally the harmonic gearbox (strain wave gearbox).  There are many geometric variants of this gearbox made by manufacturers such as Harmonic Drive.  These are expensive gearboxes (I’ve heard $2k in small quantities), and are still very pricey second hand on ebay. The… Continue Reading 3d Printed Harmonic Gearboxes