MultiBot Rotary Axis

This is a mostly 3D printed rotary axis for a cnc machine. I made it to use with my MultiBot CNC machine but it would work with any machine that can accept a NEMA 17 stepper motor.

It uses a pair of 3D printed gears and a 200 mm toothed timing belt to get a 3:1 reduction on the stepper motor. This increases the torque and resolution with minimal backlash. A pair of ball bearings support the shaft, and for now I am using an off the shelf 2" 3 jaw chuck to hold the workpiece.

Edit: added files for a 3D printed tailstock.

Add a touch of super glue to the nuts to help keep them in place if they don't fit tight in there holes.

Use a hair dryer to carefully warm up the parts if you are having troubles fitting them together. Be careful with this, it only takes a minute or less to soften things up, check often as you warm up the parts.

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Rotary Axis materials needed:

2x 15x32x9 ball bearing
https://smile.amazon.com/dp/B08KT6R23X/

48mm NEMA 17 stepper motor
https://smile.amazon.com/dp/B00PNEQKC0/

2" 3 jaw chuck
https://smile.amazon.com/dp/B08F7FYZCD/

200 mm 6mm wide toothed timing belt
https://smile.amazon.com/dp/B07V6N32B1/

4x M3 x 8 mm socket head cap screws
1x M3 x 6 mm socket head cap screw

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Tailstock materials needed:

1x 608zz Bearing
https://smile.amazon.com/Bearings-Double-Shielded-Miniature-Skateboard/dp/B07H83VV6B/

1x M8 x 100 mm hex bolt
https://smile.amazon.com/uxcell-100mm-Stainless-Steel-Threaded/dp/B0143AC67M/

4x M8 hex nuts
https://smile.amazon.com/Persberg-M8-1-25-Height-Stainless-120153/dp/B089PR8DVP/

1x M6 x25 mm hex bolt
https://smile.amazon.com/M6-1-0-Hexagon-Screws-Stainless-Threaded/dp/B08KTKTQSX/

1x M6 hex nut
https://smile.amazon.com/Prime-Line-9087834-Finished-Metric-25-Pack/dp/B07DS3W8JQ/

*** Note, buying bolts and nuts one at a time from Amazon is probably the most expensive way to do it. I recommend getting a set of bolts and nuts at a minimum, or shop around at a shop that specializes in hardware.