3D printed worm gear star tracker

[hp3dp]

I've recently got into wide angle milkyway photography and was looking at star trackers until I saw the price tags  So I thought, I'm a mechanical engineer with access to 3d printers, cnc machines and have quite a bit of experience with designing pcb's so why not make my own?

After a ton of research I ended up with a design that looks similar to the MoveShootMove tracker but made at a fraction of the cost.

Its still a work in progress but the mechanics all work and I'm now working on designing a pcb that uses an esp32 and a stepper driver to run the whole thing. 

It's all a bit overkill but anything worth doing is worth overdoing. Right?

There is still some work to do on the main gear so I can attach a ball head to it as well as the bottom plate. In the end the top and bottom plates will be made from laser cut aluminum. 

Stepper motor has a 19:1 gear ratio and the worm gear has a 50:1 ratio with a 2 start worm.

[Astronomist]

Impressive first post!  it looks very well made and thought out, and reminds me that I really must get a 3d printer someday.

[saac]

Nicely executed hp3dp; what filament material did you use?  Oh and welcome to SGL it really is a fantastic place to be and share ideas. 

Jim 

[vlaiv]

Welcome to SGL.

Very nice project!

I've been doing something similar lately, only with belts and nema 17 motor (trying to get cheapest solution possible).

[hp3dp]

37 minutes ago, saac said:

Nicely executed hp3dp; what filament material did you use?  Oh and welcome to SGL it really is a fantastic place to be and share ideas. 

Jim 

The gear is printed in black silk PLA for this first test and the worm is printed with powdered nylon 11 on a Formlabs Fuse 1. PLA is really cheap and prints MUCH faster than the Nylon 11 so its perfect for prototyping.
Once I have the design finalized, my plan is to print the gear out of the same Nylon 11 as the worm. At least as a sleeve that will go around a carbon fiber nylon filament printed hub.

The goal of this was to keep costs low but also make it efficient on power which is why I didn't go with a nema17. This little motor only needs 0.8A and also keeps the weight down in case I decide to travel with it.

I think so far I have about $75 into it including motor, bearings and hardware. Motor was the most expensive part at about $55 but they can be found about half the price from China

Here is another picture showing all of the components:

[saac]

19 minutes ago, hp3dp said:

The gear is printed in black silk PLA for this first test and the worm is printed with powdered nylon 11 on a Formlabs Fuse 1. PLA is really cheap and prints MUCH faster than the Nylon 11 so its perfect for prototyping.
Once I have the design finalized, my plan is to print the gear out of the same Nylon 11 as the worm. At least as a sleeve that will go around a carbon fiber nylon filament printed hub.

The goal of this was to keep costs low but also make it efficient on power which is why I didn't go with a nema17. This little motor only needs 0.8A and also keeps the weight down in case I decide to travel with it.

I think so far I have about $75 into it including motor, bearings and hardware. Motor was the most expensive part at about $55 but they can be found about half the price from China

Here is another picture showing all of the components:

How well do you think printed Nylon will resist wear? I've never used anything more exotic than PLA in my own prints.  I suppose at the end of day you just need to set wear limits and then swap out worn worm and main ring - almost treating them as consumable. It's a lovely neat design, very compact. Can't wait to see you report on it once running. 

Jim 

Edited April 24, 2023 by saac

[hp3dp]

The SLS printed Nylon 11 has excellent wear resistance so I expect it'll hold up for a while. Especially once you add a little bit of grease to the gears. 

This stuff is rough at first until you get a few rotations and then the rough texture smooths out and you get a very nice smooth movement on everything. I've tried taking a file to the nylon parts and after a few swipes it just glides across without removing any more material and the parts look shiny.

Good news is the parts use so little material that they're pretty inexpensive to print so swapping them out if they wear out won't hurt the wallet much.

[saac]

9 minutes ago, hp3dp said:

This stuff is rough at first until you get a few rotations and then the rough texture smooths out and you get a very nice smooth movement on everything. I've tried taking a file to the nylon parts and after a few swipes it just glides across without removing any more material and the parts look shiny.

Good news is the parts use so little material that they're pretty inexpensive to print so swapping them out if they wear out won't hurt the wallet much.

I must admit when I first saw the main ring I thought it was metal, it really does have a sheen to it. Like you say if wear does become to much they can easily be reprinted.  I'm looking at upgrading my current 3D printer later in the next few months so that I can print with a wider range of materials. At the moment I'm restricted to PLA. 

Jim 

[Elp]

Great looking project. Nylon is one of the most hard wearing materials you can 3D print in but you need the printer capability for it. Its so good a material you can CNC machine it so is good for fit and function prototyping for certain applications.

[windjammer]

That looks the business.  Elegant and neat but meaty and robust.  Just right.  Envious!