Re: Stepper motor mount for Losmandy GM-8


Khalid Baheyeldin
 

On Thu, Dec 19, 2019 at 04:28 PM, Howard Dutton wrote:
On Thu, Dec 19, 2019 at 11:48 AM, Khalid Baheyeldin wrote:
- Testing whether the resolution is better, that is much harder.
I think the thing to do is a test similar to the hack-a-day one but with more motors, more drivers, and torque loading similar to what moves my G11 around.  To that end I also ordered a 116 oz-in holding torque NEMA17 400 step motor as I feel it might turn out to be the best performer.  I could use a laser diode spot across the room/ruler to take angular measurements but probably will use my 200k count encoder instead since it'll be quicker and more accurate probably.  I can hack the WiFi addon to gather the measurements.
An advantage of those 5-phase motors is that they could be connected with just 1:1 pulleys for EQ4 (144 teeth at 1/64 microstep).
That can be helpful in cramped situations where a bigger pulley is obstructed (like my mount).

The disadvantage is that the external drivers are bulky and unlikely to go into the box.
And the cost of it all is significantly higher than bipolar options.
Another disadvantage is the lack of on the fly mode switching.

Maybe size and cost will go down in the coming years.

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