My astronomy project:
3D CAD design of a 3" Rack and Pinion focuser

Content:

Ideas about 3D-print rack and pinion gears:

1. 3D-Printing Rack & Pinion gears
2. How to implement the Rack & Pinion into the focuser
3. Combined Rack & Pinion and worm gear
4. 3D CAD focus shaft holder and focus chassi
5. 3D CAD and print of worm gear
6. To be continued

Look at these projects too:

1. Repair and adjusting focus friction
2. 3D CAD design of a 3" Rack and Pinion focuser
3. 3D CAD design of a 3" Push Pull focuser
4. Focus and camera rotator

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

5: 3D CAD and print of worm gear

Earlier when I printed the helical gear for the rack & pinion gear I added a helical gear at the end for an extra gearbox. I need it to have the correct gear ration for a NEMA 17 stepper motor without internal gearbox. Now I do the worm gear.

My first worm gear. It's designed to hold two 15 mm roller bearings. The outer diameter is 15 mm and it has one tooth. The hole is 5 mm to attach to the stepper motor of NEMA 17 model. A big motor but I design it to take a load of 4 kg.

Not to bad, have to do something of the smoothness of the surface.

The stepper motor I had in my desk, a NEMA 17 model with 200 steps per revolution. The shaft is of 5 mm diameter.

With the worm gear attached on the stepper motor's shaft. Later I shall calibrate the 3D-printer and compensate to get the hole of correct size. Now I have to drill the holes to get it perfect.

Match the helical spur gear but I need to set the helical angle to another value. If I also can get the teeth to have a curved shape it will be even better.

The center to center distance between the shafts is 29 mm. I need that distance to finish the drawing of the focus chassi.

I stop here with my Rack and Pinion project. Instead I develop a more advanced construction with Push Pull design: 3" Push Pull focuser.