Sky-Watcher Auto Focuser

[Al-man]

I have a Skywatcher 150PL and am thinking of fitting a Skywatcher Auto Focuser. Looking at youtube videos for similar scopes, it seems that one of the focuser knobs has to be removed, but mine has no grub screw. I have read that on some of these scopes the focuser knob may be screwed or glued on and that the Skywatcher Auto Focuser is not suitable for this type.

I have tried to see if the Focuser knob would unscrew, but couldn't shift it and was worried about using too much force. Has anyone fitted one of these to this type of focuser ( as shown in pics) and if so how ?. Were there any modifications needed to fit the Auto Focuser ?

Edited September 28, 2018 by Al-man

[Merlin66]

I think these knobs are threaded, the shaft having a taper and thread end.

I'd try holding one knob and then turning the other anticlockwise with a fair effort to get it to release....

I use the SW focus motor on all my telescopes - works well for me.

(With the 10:1 versions I belt drive the 10:1 knob - 6mm xml belt, 30 tooth pinion on the motor)

 

[Swamp Gas]

is it worth popping off the four black screws to reveal the gear inside, maybe there is a flat spot or something you can grip or vice?

[Al-man]

18 hours ago, Merlin66 said:

I think these knobs are threaded, the shaft having a taper and thread end.

I'd try holding one knob and then turning the other anticlockwise with a fair effort to get it to release....

I use the SW focus motor on all my telescopes - works well for me.

(With the 10:1 versions I belt drive the 10:1 knob - 6mm xml belt, 30 tooth pinion on the motor)

 

Thanks, you were right, I got one undone with a bit more effort.

9 hours ago, Swamp Gas said:

is it worth popping off the four black screws to reveal the gear inside, maybe there is a flat spot or something you can grip or vice?

I removed the four screws as you suggested, although there was no flat on the spindle, I removed the spindle which made it much easier to undo one of the focuser knobs.

[stu640]

On 29/09/2018 at 18:06, Al-man said:

Thanks, you were right, I got one undone with a bit more effort.

I removed the four screws as you suggested, although there was no flat on the spindle, I removed the spindle which made it much easier to undo one of the focuser knobs.

Hi Al-man, hope you're still about on here? I'm just about to go through this process. I've not found anywhere else on the web anyone discussing this exact problem for the 150PL. You're it! Did you successfully fit the auto focuser after getting the knob off? How did it work out? Thank you! Stu

[Jiggy 67]

Just a word of warning (and advice) with these auto focusers. They work with a type of solenoid which works as a brake so you cannot manually move the focuser. I’ve had two of these focusers and on both occasions the solenoids failed, one in a few months and the other in a matter of weeks! This made the focusers useless.  Unfortunately I had misplaced the original knobs so I ended up buying a Moonlite focuser....My point is make sure you keep the original parts where you can find them again. I couldn’t find any replacement parts anywhere 

[Merlin66]

Jiggy,

I’ve been using the  SW/ Orion motors for many years- I now have six of them on various telescopes. I honestly don’t think there is any solenoid in the motors. When the power is applied there is a degree of reverse braking effect.

IMHO they are a very effective, cost effective, solution to semi- remote focuser operation.

Recommended.

 

[Jiggy 67]

2 hours ago, Merlin66 said:

Jiggy,

I’ve been using the  SW/ Orion motors for many years- I now have six of them on various telescopes. I honestly don’t think there is any solenoid in the motors. When the power is applied there is a degree of reverse braking effect.

IMHO they are a very effective, cost effective, solution to semi- remote focuser operation.

Recommended.

 

I don’t know if it’s a solenoid but but there is a means by which the device stops the manual turning of the focuser. On both occasions in my experience, this failed allowing the focuser to be manually turned which meant the auto focuser no longer worked. The only thing I know is that it wasn’t operator error, they were only ever used as they were meant to be used, and I don’t think it’s how I fitted them, although I wouldn’t bet my mortgage on it!

 I was a big fan when they worked but for the above reason I wouldn’t buy one again...maybe I was just unlucky 

Edited May 18, 2020 by Jiggy 67

[banjaxed]

I have been using one for about a year without any problems. If there is any downside it is they are extremely SLOW.

[Al-man]

On 17/05/2020 at 22:02, stu640 said:

Hi Al-man, hope you're still about on here? I'm just about to go through this process. I've not found anywhere else on the web anyone discussing this exact problem for the 150PL. You're it! Did you successfully fit the auto focuser after getting the knob off? How did it work out? Thank you! Stu

Hi, Sorry for the late reply, I haven't been on here for a while. I hope you got it sorted ok. Mine works fine and I control it remotely on my PC via USB lead. The speed can be adjusted in the program.

[stu640]

On 24/06/2020 at 16:37, Al-man said:

Hi, Sorry for the late reply, I haven't been on here for a while. I hope you got it sorted ok. Mine works fine and I control it remotely on my PC via USB lead. The speed can be adjusted in the program.

Thank you so much for getting back to me. I’ve not had the courage to get the pliers out on that knob yet, but if it’s worked out well for you, then I’ll have a slug of whisky and go for it!!!