Bart wrote: Indeed Jo,
I used one of those slim line.
Nema 14 could also be ok, but I had the 17 lying around and a bit of headroom in the torque is nice to have.
I prefer the Trinamic fdrivers, for they are just absolutely smooth, which just 'feels' good.
Yes Mohamed, the code to control the stepper motor driver (microstepping, speed, acceleration etc) is in the Arduino code.
I'm busy now, but will upload files later this week.
Bart wrote: I use a motor similar to this one:
there exists also a version with 400 steps per revolution.
Bart wrote: You don't need all that resolution on a Celestron. it is already 'geared' by the focuser thread inside. 200 steps/rev is plenty. 400 would also be fine.
I use 400 steps/rev on my Maksutov Newton telescope with a Crayford style focuser. This is a much more sensitive focuser, because the translation per rotation of the focus shaft is more. Diameter of shaft: 4 mm, and so: 4 * Pi / 400 = 0.0314 mm/step (full step!) This is a faster system ( f / 4.8 ) which is more critical to focusing than the Celestron ( f / 6.3 ) and even then it -just works- with no problem.
dmsummers wrote: @mhammady: The 8SE appears to have a thread pitch of 24 threads/inch or 0.94488 threads/mm (1.0583mm/thread(or 1 rev)). You're at F10, so your CFZ is on the order of 2.44*10^2 (244um). If you were to use the Celestron (1k cnts/rev), the math works out to 1.058um / count or 230 counts "length" for the CFZ. The ASI has 5760 cnts/rev, which works out to 0.1837um/count (1328 counts CFZ length). That's overkill unless you know you'll be adding a focal reducer. As Bart indirectly points out, at F10 and 200 counts/rev, you'd have a CFZ length of 45 counts. That seems "skinny" to me. 400 counts/rev would give you 90 counts CFZ length. 1000 would give you room for that focal reducer you're going to want . My 2 cents. Cheers, Doug.