I had a friend that had a motorised telescope. It had a DC motor, with a very high reduction ratio. I think one would see fluctuations with a stepper motor.
Also, I wouldn't use a belt at all. Drive a smooth roller and use a friction drive against a large disc. This also allows you to manually turn by slipping the disc on the roller for an easy setup. Most theodolites use this arrangement. Teeth will just be too jerky when viewing stars.. On Fri, 10 Jul 2020 at 11:39, andy pugh <bodge...@gmail.com> wrote: > On Fri, 10 Jul 2020 at 02:00, Chris Albertson <albertson.ch...@gmail.com> > wrote: > > > Belts can go to about 6:1 at best a double belt reduction only goes to > 36:1 > > I don't see why there is any limit to the possible reduction of a belt > drive, if idlers are added to increase the wrap. > If I was doing this (and this particular application is something that > I have considered) I think that I would use a rotary variant of the > "servobelt" system: Glue a length of T-section beliting to a circular > component with the teeth pointing out to make a sprocket, and then > have a close-spaced pair of rollers to keep the belt wrapped round > the sprocket except for a short loop that pops out and wraps round the > stepper pulley. > > > > He is doing only > > about 10 Hz. > > In that case I think that a user-space loop in something like Python > would be fine, just monitor the time using an accurate RTC (GPS > module?) and have the loop say "have I made as many pulses as I should > have for this time of day?" and either make a pulse on a GPIO pin, or > not, accordingly. > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
