[vignesh1230 (Vignesh)]

Originally Posted by alistairsam

hi,

That's pretty impressive and I'll look forward to your updates.
I'd be interested in how you tackle the ASCOM interface without writing a driver.

I've used the DRV8824 in a fork mount with a stepper and the logic I used for autoguiding was that the ST4 pulse would be monitored by the MCU and would either add or subtract from the current period that the pulses are based on.
This worked well and I didn't account for refraction.

There's a thread here about sidereal rates and I believe you need to track at the King rate to account for most refraction.

Encoders at the axis would be good but would need to be hi-res to provide the resolution required. Renishaw encoders are used in High end mounts with direct drive.
however, as long as you keep backlash and PE low with your gear mesh, you would have repeatability by keeping count of the steps similar to what's done with the EQ series mounts where no encoders are used. Just steps.

The render does look very good. will it be milled or cast?

Cheers
Alistair

Thanks Alistair

EDIT: About the Ascom(i forgot about it when i typed this up at school), I was either planning on emulating a mount made by Sky watcher and using it with EQAscom, or actually write a driver myself. Ive had a thorough look through all the documentation available on the telescope mount drivers, and I think, given time, Ill be able to make a working driver, and then make refinements and so on.

Its good to know that someone else has used the DRV8825 chip to control a telecope mount haha. I was originally planning to just use pulse guiding to guide the telescope but I guess i can add an ST4 port just in case. In regards to not accounting for refraction, how good was the pointing accuracy, and how much work did the guider have to do?

Definately cant afford Axis encoders like the Renishaw. Hence the idea to put an encoder on the worm itself, to control the PE better.

The whole thing is designed to be milled and lathed, for simplicity's sake.

I have made a couple of small EQ mounts in the past and the most difficult parts to make are the worms and the worm wheels. Are you sure your friend's workshop has the specialized tooling that is required?

The worms and worm wheels are the parts that I'm most worried about. I'm not sure how I'm going to tackle them. I have been to his workshop and he does own a lot of different CNC lathes, but I'm pretty sure he dosen't have like Class AA hobs or anything. Ill check with him..
He may be able to do everything but the gears actually, but there seems to be 2 gear machining companies near his workshop, so ill be trying to get a quote soon