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Thanks Everyone.
I will be testing it shortly, unguided to start with and will post results.
Justin, I'm more than happy to help with your motor drive if you're interested.
Do you know what your total reduction is and what the reduction on just the gearbox is? also what is the speed of your motor.
there are a couple of options for your drive.
you could use a dc motor with a higher ratio gearbox than what you have (higher torque) and control its speed with a pwm motor controller, readily available for under $20. they usually come with a rheostat.
you could also use a DC motor as a closed loop system, that is an encoder on the motor shaft, and get constant speed, bit more complicated but doable. I do have spares lying around pulled from printers.
else you could use a stepper with a gearbox and I could send you one of my stepper driver boards with a picaxe controller.
The one I'm testing right now, I've programmed two buttons. if you press one button, it adds 10 microseconds between each pulse or step, so slows it down for each press.
other button reduces 10 microseconds, and thus speeds it up in small increments. it can even display the current value.
manual guiding if you like, just till i get the QHY5.
you'd get much more control this way.
challenge will be to get a 1.8 degree stepper with a matching gearhead with sufficient reduction as most nema steppers with gearheads are very expensive, that's why I went with the mclennan gearboxes and my kludge drive.
With the 1.8 deg stepper and with 1/32 microstepping, I use a frequency of 87.3Hz to achieve sidereal rate with my gear ratios. (1178:1)
PM me if you'd like to explore and I can help with the electronics.
the other thing would be to use shorter focal length mirrors, I tried imaging with an F6, and moved to an F4 and noticed huge reduction in exposure time required, and added benefit of a smaller OTA. downside is you need a coma corrector, but well worth it. F4 will reduce your flexure problems and decrease torque required.
Bojan, I agree, there might be significant PE, but unlike a worm wheel, since this is a 3 stage reduction gearbox with very small pitch gears, would PE be noticeable as the periodicity of the PE in the first stage gear would be very small, and might not even be reflected in the output as its a 250:1.
I'm waiting to get a guidecam, that would give me a much better indication.
will carry out some tests and see.
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