Better initial alignment tips

Harmonic Geared Mount
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cwoodhou
Posts: 30
Joined: Fri Mar 26, 2021 9:27 pm

Better initial alignment tips

Post by cwoodhou »

I discovered that the home position on my mount was not too well set and in particular, my DEC pointing was several degrees off.
The markings on the mount body are a guide and I initially set the home position using these. They are not too far off but on the RA axis, both pairs of markings do not align at the same time. The saddle plate is held on with four bolts, which allows it to be turned 90 degrees... it also has a lot of potential variation in the assembly condition and mine was about 2.5 degrees off orthogonal.

1) I removed the saddle plate, leveled the mount base and then after homing put the mount at latitude = 90,
2) I slewed the RA axis slightly to level the top E-W.
3) I then raised the mount to latitude =0 and attached the saddleplate. I carefully leveled its top edge before nipping up the bolts.
4) I made minor changes to DEC to get it perfectly level (I use a bubble level with 0.03 degree markings.)

I then SET the home position to lock in the calibrated home position.

The initial slew is much more accurate now and the target is within the FOV of the camera.

hope that helps
Jockey
Posts: 25
Joined: Sat Jan 28, 2023 10:47 am

Re: Better initial alignment tips

Post by Jockey »

Thanks for the info.

Cheers
cwoodhou
Posts: 30
Joined: Fri Mar 26, 2021 9:27 pm

Re: Better initial alignment tips

Post by cwoodhou »

On my mount, there is still something strange with DEC slew accuracy. Even with refraction disabled, pointing E or W at zero altitude does not give me a horizontal scope. It points upwards by about a degree in both cases. I have raised a ticket. Not sure if it is just my scope or something more general.
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