Nema17 1:3 Speedbox

thingiverse

The Nema17 1:3 Speedbox is designed for adding a 1:3 gearing increase between the Nema17 drive motor and the cable for a Zesty Nimble. This is my second go at an overdrive speedbox for the Zesty Nimble. This time the goal is efficiency and compactness. I've included a holder option that I use for mounting this to my printer based on what I'd done with the Nimble V3 previously where it allows the user to have some amount of angle and flexibility. Feel free to make you're own mount for this that fits your needs. The thickness I used was 3.75mm. After playing with this for a bit I am happy to say that there is considerably last friction than my last design, though this does come at the cost of needing bearings on hand to make it work. Speedbox Hardware: - (2) m3x30mm machine screws (button head cap screws recommended) - (4) m3x24mm machine screws (button head cap screws recommended) - (4) m3x12mm machine screws (socket head cap screws recommended) - (6) m3 hex nuts - (6) 105ZZ bearings. This is what I use: https://a.co/d/b23AKL8 - (2) m3 set screws (flat tip is preferred, especially for the cable gear Hinged Holder Hardware: - (2) M3x8mm heat inserts - (2) M3x12mm machine screws (button head cap screws recommended) Assembly: - Drive gear - Insert one bearing - Drill out center to ensure proper fitment onto stepper shaft - Place a bearing onto the stepper shaft before placing the Drive Gear - Mount Drive Gear onto stepper shaft - Press it on until the shaft is flush with the INSIDE of the bearing (the Cable Gear needs to fit inside of the entire bearing yet) - Secure with a set screw - Cable Gear Notes: - This WILL increase the amount of torque needed to drive the Nimble - A pancake motor will not work - 1:3 ratio means 3 times the torque needed to go the same speed. - Use lubrication! - As the cable spins faster, its friction increases, especially if there are any bends in it including a bunny ear. - Retractions are noisy - There is a clack sound similar to an old keyboard or even typewriter for every retraction - Extrusion is silent :D