MyfocuserPro v2 on GT81

[Wyvernp]

Afternoon,

Quick question, has anyone fitted their GT81 with a MyfocuserproV2?

I have a couple of Arduinos laying around and thought this would make for a fun project. Although looking at the mounting on the bottom of the focuser there seems only to be one screwhole which is unoccupied by a hex key screw. Am I ok to remove the other?

Also do you remove the second focus knob and direct drive from the stepper or belt drive to the 10:1 focus knob?

I have a mill so I think I can fabricate a suitable mount plate for it so I don't think that should be an issue.

Any advise on these would be much appreciated.

Wyvern.

[Dr_Ju_ju]

I don't know the GT81 William Optics ? but I'd be wary of only using 2 mounting holes, is the one occupied or not ?? and is the other for manual 'focus lock' ?   

If I was belt driving , then mounting the motor parallel to focus spindle axis, so that the belt could go around the 10:1 knob, but it doesn't have to, as you can setup step rates within the software.

Direct driving means removing the non 10:1 knob & mounting the stepper in-line with the focus shaft, this is the method I prefer, but then there is a large lump sticking out, but then the Skywatcher ED80 etc., usually have 4 screws for the focuser shaft mounting plate, so I just use longer screws & fit the motor bracket there.

[Wyvernp]

Thanks for the quick and useful reply. 
this is the underneath or the focuser.

 

i see 2 holes either side of the QC sticker, the top one is free and the pictured bolt goes into it. The rest all seem to already be used. 
Worse case I can custom make a knob that can fit in the first 5 turns or so of the thread but I’d rather not have to. 

[m.tweedy]

My GT81 is the original version so don’t know it it’s different. Mine has a Lakeside and has never slipped as the stepper motor holds it securely.

i hope that helps

 

Edited April 11, 2020 by m.tweedy
additional info

[Wyvernp]

Perfect! Thank you, the both of you. Great to see this can be fairly easily done.

[m.tweedy]

One more thing to add. The focus lock screw has never been used since attaching the Lakeside. It is loose but kept in place so i dont lose it.

 

[Wyvernp]

Well, I've got all the electrics working. So just waiting for the aluminium bar for the mounting plate and rod for the bit that attaches the motor to the focuser. I've decided to keep the fine focus knob intact and remove the knob on the other side as the stepper motor has a 27:1 gear box so the steps are tiny.

Edited April 16, 2020 by Wyvernp

[Wyvernp]

Well it’s not pretty but it will definitely do!

that stepper is bloody heavy though. I hope I’ll be able to balance it. 

[Dr_Ju_ju]

To achieve balance, if you don't have any counter weight, rotate the OTA such that the motor is in-line with the mount and not off to the side, but then you may need to juggle the guider etc...

[Wyvernp]

Yes of course, that makes perfect sense. Thanks. 
 

Just finished wiring up the control box with the Arduino and sensors/controllers. 
 

 

Again, not the neatest job but it will work. 

Edited April 27, 2020 by Wyvernp

[Chriske]

m.tweedy...Is that C5 and C6..?(Avatar)

[m.tweedy]

On 28/04/2020 at 16:37, Chriske said:

m.tweedy...Is that C5 and C6..?(Avatar)

L4-L5