Motorized Stars Tracker

by pchretien Sep 12, 2011
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I think a DC gear-motor would do a fine job. Never seen a tracker made with stepper motors before. Now I know why!

Are any improvements made? Any luck with the photo's?

OK, so a 291mm radius arm at 15deg/hr means 0.0213mm/sec, 1.279mm/minute, or about 1.023rpm on a M8x1.25 or 0.992 RPM on a 1/4-20 bit of threaded rod. Cool.
I think my dad once had something like this driven with a cheap synchronous motor driven by a 555 putting an amplified ~59.53Hz square wave backwards through a 12V:120V transformer.

I suspect from the photos you are using a 7.5 degree per step (or thereabouts) stepper. If that is the case, upgrading to a 1.8 degree per step might help.

A couple of ideas to minimize the vibration...
A vibration suppression mount (essentially a shock absorber) right under the camera, and one between the board and the camera's mount will go a long way in this configuration

A mount where the camera sensor is in line with the board will help.

Use soft wood with plastic bolts and rubber vibration suppression mounts.

Use a brushless DC motor mounted as far away from the camera as possible. Then add another gear set. Idea being to get the frequency of the vibrations into the suppression mount's sweetspot.


I was thinking all weekend about designing a nice open source star tracking mount that can be 3D printed, but I never found this Thing because you never mention the word "telescope" and thats what I was searching for. Perhaps tag it with that or mention it in the post? Clearly this is technically for a camera and not a telescope, but people searching for telescope related items would probably be interested in this! Though I see now I should have just searched for "astronomy". Not sure why I didn't really.

Anyway I'm thrilled to find that there are actually star trackers on here! I'll have to build one of these when I get my Ultimaker. :)

Eh, thanks for your comment! I added the telescope tag.

I'll publish a new version in the next few days. The mechanism will be a lot simpler and much more compact.

I still have a lot of work to do but my weekent at the ohsummit and the Maker Faire gave me the push I needed ...