SkyWatcher Auto Focuser on SW Explorer 130P?

[SCOOB_81]

Hi Folks,

I’ve read articles of people fitting the Skywatcher Autofocuser to a Skywatcher Explorer 130P. I know it isn’t designed for the scope, but that the bracket can be modified. I was wondering if anyone had any experience of this, please?? By that I mean is it a fairly straight forward job?

http://www.firstlightoptics.com/astronomy-cables-leads-accessories/skywatcher-auto-focuser.html

I’m sorry if I’ve missed this being answered previously using the search function.

Thanks!

Sean.

[assasincz]

I have managed to attach the Skywatcher Auto Focuser to my SW 4.5" reflector, which, I believe, has the same rack and pinion focuser as 130P has.

It requires a bit of DIY not only regarding the bracket, but with the way to attach the motor to a focusing rod as well, as non of the supplied adaptors are intended for the rack and pinion focusers.

I have made the bracked from a piece of 2 mm aluminium of preferred width and I have made the piece that joins the focusing rod with the motor from a piece of hollow aluminium rod and fixed it in place with a couple of worm bolts. It does not look elegant, but works quite well.

I have supplied pictures.

[cthorpey]

Perfect timing, I am going to be doing the exact same mod myself fairly soon, I have the other version of the focuser but the theory is the same, Thanks for posting the piccys.

[Gina]

Looks good And who says it's not neat? Looks neat enough to me - nice job

[EBU]

Really nice job!

[assasincz]

Oh and it is worth mentioning that the bolts that attach the bracket to the focuser had to be replaced with slightly longer ones, as those default were, after adding the bracket, too short. And also, the focusing knobs are screwed to the focusing rod - and believe me, I was attempting to knock it off the rod using a hammer when it finally dawned on me to try and twist it a bit what an idiot I was.

Of course the bracket needn't be so long, but this way, you do not need to cut the focusing rod to make it shorter.

Thing is though, this mod is already a history, because I have fitted the auto focuser to my new 300P and because I was patient and did not cut the focusing rod to make the whole setup more compact, so I just took the atuo focuser off and screwed the focusing knob back.

[SCOOB_81]

Thanks for your explanation and pictures, assasincz – they're fantastic and you’ve done a great job!!

I was thinking exactly the same, where I’d not like to permanently alter any of the components as I’ll upgrade my scope in the not so distant future, too.

Order placed today.

Thanks again,

Sean

[Gina]

Yes, good thinking I prefer not to hack bits off the main thing if I can avoid it.

[brucen]

I have been looking to do this for a while but have 2 problems.

First, I seem to have a different focusing rod and I have tried unscrewing the knobs but they don't seem to want to come off. Secondly, the rod is not straight (was like it from new) which does not affect manual focusing but would not work with the motor. I could probably straighten the rod if I took it off but won't bother if the knobs are not removable. Has anyone removed this type before?

Edited February 11, 2012 by brucen

[SCOOB_81]

Hi Brucen,

That setup is very different to mine, and this is standard from new? With the knobs, they haven't got a hidden screw holding them in place? Have you taken a look under the rubber grips?

Sean.

[brucen]

Hi Brucen,

That setup is very different to mine, and this is standard from new? With the knobs, they haven't got a hidden screw holding them in place? Have you taken a look under the rubber grips?

Sean.

This is how it was from new - July last year. The knobs are hollow and there are no screws to be seen. I have twisted pretty firmly and there is no movement. I don't really want to take it apart unless I am sure they will come off as I don't want to have to saw it. The fixing plate on this one is also secured by 4 screws rather than 2 so it is obviously a completely different focuser.

[SCOOB_81]

This is how it was from new - July last year. The knobs are hollow and there are no screws to be seen. I have twisted pretty firmly and there is no movement. I don't really want to take it apart unless I am sure they will come off as I don't want to have to saw it. The fixing plate on this one is also secured by 4 screws rather than 2 so it is obviously a completely different focuser.

I see what you mean, mate. I've just has a quick google and it is completely different to my own.

I'm sorry I've not been able to help.

Sean.

[assasincz]

It is obviously a completely different focuser.

I suspect it is a 2" rack and pinion focuser rather than 1.25" one - an I close to the mark?

If so, it is indeed a different focuser entirely. That said, I doubt that the focusing rod and the knobs are all machined from one piece of metal, as it would be indeed too pricey. In fact, I have seen in a review of the very same scope here at SGL that the knobs seem to be made from aluminium, which is unlikely to be the same material the focusing rod is made from, so they have to be seperate. Perhaps somebody with the very same focuser will enter this thread and give you an advice on how to get the focusing knobs off, but I would say, do not give up - it is unlikely that it is all one piece.

If the knobs are not screwed on, then, they ought to be held in place either by locking screws, glue or they might be pressed to the focusing rod.

Furthermore, if the focusing rod is bent, presumably on one side, then just remove it from the focuser and flip it around.

Edited February 11, 2012 by assasincz

[brucen]

I suspect it is a 2" rack and pinion focuser rather than 1.25" one - an I close to the mark?

If so, it is indeed a different focuser entirely. That said, I doubt that the focusing rod and the knobs are all machined from one piece of metal, as it would be indeed too pricey. In fact, I have seen in a review of the very same scope here at SGL that the knobs seem to be made from aluminium, which is unlikely to be the same material the focusing rod is made from, so they have to be seperate. Perhaps somebody with the very same focuser will enter this thread and give you an advice on how to get the focusing knobs off, but I would say, do not give up - it is unlikely that it is all one piece.

If the knobs are not screwed on, then, they ought to be held in place either by locking screws, glue or they might be pressed to the focusing rod.

Furthermore, if the focusing rod is bent, presumably on one side, then just remove it from the focuser and flip it around.

Good point, yes, it's a 2" focuser. The knobs are definitely separate but are either glued or are a very tight fit as there are no screws. I had not thought about turning it around but this would solve the problem as it is only one end - the one I need - that has the elliptical orbit. Perhaps I will whip it off and give the knob a few taps with a hammer to see if it shifts.

[Reggie]

Those pictures look very much like a celestron 80ed R&P focuser, http://www.celestron.com/media/catalog/product/cache/2/image/9df78eab33525d08d6e5fb8d27136e95/5/2/52280_80edrefractor_large.jpg

In the centre of the focuser knob, you can just about make out some little celestron stickers , those stickers are on a round nub, which the focuser shaft screws into, check if you focuser has that nub, if so you can be fairly certain that it's a screw on and you probably just need to be a bit braver twisting it to free it, I remember mine was quite stiff, obviously holding one knob whilst turning the other one will help (just in case you're tempted to just rack the focuser in and use that to hold the shaft whilst you twist the knob).

If it's not screwed on or screw on, then it's push fit, which means that twisting it will not be an issue as it will still come free, mine is 2 different metals for the shaft and the knob, the knob is ali, the shaft looks chrome plated.

Edited February 11, 2012 by Reggie

[brucen]

Those pictures look very much like a celestron 80ed R&P focuser, http://www.celestron.com/media/catalog/product/cache/2/image/9df78eab33525d08d6e5fb8d27136e95/5/2/52280_80edrefractor_large.jpg

In the centre of the focuser knob, you can just about make out some little celestron stickers , those stickers are on a round nub, which the focuser shaft screws into, check if you focuser has that nub, if so you can be fairly certain that it's a screw on and you probably just need to be a bit braver twisting it to free it, I remember mine was quite stiff, obviously holding one knob whilst turning the other one will help (just in case you're tempted to just rack the focuser in and use that to hold the shaft whilst you twist the knob).

If it's not screwed on or screw on, then it's push fit, which means that twisting it will not be an issue as it will still come free, mine is 2 different metals for the shaft and the knob, the knob is ali, the shaft looks chrome plated.

Certainly looks and sounds similar. I can't twist any harder with it on the scope so I will need to take it off and put it in the vice to see if I can shift it. Just need to pluck up the courage now!

[brucen]

Should anyone else have the 2" focuser I can confirm that the knobs do unscrew although I had to hold the rod in a vice to do so as they were so firmly tightened. There was also a red powdery residue left on the thread so I assume some form of adhesive was involved as well.

[Reggie]

Excellent Job Bruce, I'm surprised that you had to use a vice to remove the knob though, I now wonder if a little bit of heat might've done the trick and loosened the red stuff?

[brucen]

Excellent Job Bruce, I'm surprised that you had to use a vice to remove the knob though, I now wonder if a little bit of heat might've done the trick and loosened the red stuff?

I padded the vice so that it would not cause any damage so it was not that risky. I also managed to straighten the rod as one end was bent a little so it was a worthwhile exercise. It would not be that easy to heat the thread due to the shape of the knob but might be possible.

[acktiv8]

Thanks for your efforts Brucen; I was just about to embark on this mod myself and was wondering how to get the knobs off the Skywatcher 2" focus rod. The rod on my telescope appears to be bent too (from new!); does everything still work OK after you had managed to straighten it? If it is supposed to be bent, it seems to be a strange design feature!

Edited February 15, 2012 by acktiv8

[brucen]

Thanks for your efforts Brucen; I was just about to embark on this mod myself and was wondering how to get the knobs off the Skywatcher 2" focus rod. The rod on my telescope appears to be bent too (from new!); does everything still work OK after you had managed to straighten it? If it is supposed to be bent, it seems to be a strange design feature!

Mine was only bent at one end and a few gentle taps with a small hammer put it straight. Worked fine before and works fine now - just looks better as the knob stays in one place when it's turned!

If yours is only affected at one end it could either be straightened or you can just use the end that is straight already as it can be reversed. Good luck with the mod.

[acktiv8]

Thanks brucen. Haven't taken it off yet so will check if only one end is bent once it is off and make a decision then. Thanks again to you and assasincz for putting your experiences with this mod on the forum.

[brucen]

Thanks brucen. Haven't taken it off yet so will check if only one end is bent once it is off and make a decision then. Thanks again to you and assasincz for putting your experiences with this mod on the forum.

You should be able to see before you take it off. Turn the focuser with one knob and see if the other just turns on its axis or whether it does a bit of an orbit. Then do the same with the other knob. If there is any movement I don't think the motor, which will be clamped to the focuser, will like it and will almost certainly shorten its life even if it works at all.

[Monty]

I must be lucky, mine seems to move when I twist the knobs by hand in opposite directions and the axle seems straight as well.

[acharris77]

My knobs will twist off on my SW 130p Goto scope. And this 2" R+P focuser is the same that is fitted to a Celestron 130slt Goto I think, as if you look on the forums I posted about this about 2 years ago and someone posted a pic of a 130 slt focuser and this accepted the autofocuser straight out of the box as it is a R+P focuser.

I am going to try it one day and see if it fits.