DH Speedbox

The DH Speedbox is designed for adding a 3:1 gearing increase between the Nema17 drive motor and the cable for a Zesty Nimble.

Note: the ring gear in the ring stand acts a little under-sized currently. Scaling X and Y to 103% seems to work until I can correct this issue permanently.

Hardware:
- (5) m3x8 machine screws (button head hex screws recommended)
- (1) m3x10 machine screw (button head hex screw recommended)
- (1) m3 hex nut

Optional Hardware:
- Extra long Nema17 motor (more torque for higher speeds and/or tighter cable bends)

Features:
- Only need fasteners to install
- Double Herringbone (DH) gears to provide inherent stability within the gear train
- Designed for easy install

Notes:
- This WILL increase the amount of torque needed to drive the Nimble
- A pancake motor will not work
- 3:1 ratio means 3 times the torque needed to go the same speed.
- This is a lossy drivetrain, lubrication will definitely help (I use a spray-on silicon lubricant). Using oil or grease will help it run quieter, but the viscosity of either will increase the required torque.
- 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
- Run a break-in period. Mount it to just the motor, make sure it's lubricated, drive it at high speed both directions for at least 1 minute each direction.
- Optional, use a drill with a square driver to do this via the sun gear for less hassle.
- This is also a good time to tune the tightness of the ring gear screw, some gap will likely be needed depending on the print fidelity. The goal is to have the split gear tooth be the same width as the remaining teeth and for the gears to roll through it with ease.

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