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Hi guys, I have made a video of how to mount a Primalucelab Sesto Senso focus motor on a true 3" Feather Touch 3215 focuser.
I thought some of you might wonder how to use the extra collar you need to mount the motor on to the bigger versions of the FT focusers, and also how to align the motor shaft.
So my birthday just past so money to splash on astro stuff , i will have my 1000D modded by juan at cheapastrophotography and also have ordered an autofocuser from deepsky dad https://deepskydad.com/autofocuser i know they can be done DIY but this is a neat package and costs about the same as a SW autofocuser and a hitechastro focusmaster and i`m no electronic wizard and pavel seems to have a good product and works with ascom and confirmed it works with APT i will update in a few weeks time when hopefully i will have received and tried out .
I have a Helios 200p (identical to the Skywatcher) mounted on an EQ3-2.
I know it is overloaded but I find it OK for visual provided I give it a couple of seconds to settle down at high powers.
I intend to motorise the mount using stepper motors & an Arduino. It will be tracking for visual only with a possible upgrade path to GoTo.
Since I dont need fantastic precision and having read the relevant threads on this forum, I propose to drive the RA worm directly & the DEC with a simple belt drive. By avoiding a step-down gear set I will still be able to use the manual slo-mo controls without disconnecting the motors. I think that centering the target with the slo-mo's & then switching on the tracking will be nicer than using fast-forward & fast-reverse controls.
But no step-down means no torque amplification. So how much torque do you need to drive an overloaded EQ3-2. I decided to do some quick & dirty tests.
200p with 25mm Plossl & 9 X 50 Finder, payload about 9kg.
EQ3-2 with 10kg of counterweights
Improvised wooden pulley, effective radius 0.375 inch
2 X 1kg barbell weights
piece of string
For each axis ,with the clutches locked, a 1kg & then 2kg load was hung from the pulley & released. This was repeated for the opposite direction of rotation.
DEC 1kg Torque 13.5 oz.inch Rotated smoothly at about 90 degree/minute
DEC 2kg Torque 27 oz.inch Rotated quickly at about 300 degree/minute +
RA 1kg Torque 13.5 oz.inch Did not rotate
RA 2kg Torque 27 oz.inch Rotated smoothly at about 90 degree/minute
The required torque for RA would be on the limit for a (cheap, ungeared) NEMA 14 stepper but a NEMA 17 motor with a torque of 84 oz.inch should be up to it.
So now all I have to do is order the bits & learn how to use an Arduino.