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Helical to Feather Touch SMII

Posted: Thu May 07, 2020 12:25 pm
by hopskipson
I recently acquired a new Solarmax II DS 90 with 30 mm blocking filter. I have yet to try it out but am curious on how to change the helical focuser to a Feather Touch. I'm sure someone here has done it. Does anyone have pictures they could post on the procedure? I removed the allen screws from the slide tubes but I can't get any of the parts apart. I figured I would ask here before going further. Thanks!

Re: Helical to Feather Touch SMII

Posted: Sun May 10, 2020 11:53 am
by marktownley
Hi James.

My SM90 has a Feather touch on it, here are some pics.

Image2020-05-10_09-52-56 by Mark Townley, on Flickr

Image2020-05-10_09-52-18 by Mark Townley, on Flickr

The focuser was on when I bought it second hand, but looks to me like the whole original helical just unscrewed off the tube to be replaced by the FT.

Mark

Re: Helical to Feather Touch SMII

Posted: Sun May 10, 2020 4:13 pm
by hopskipson
Thanks for the pictures Mark! I googled it and Moon Lite had a nice video on replacing the focuser. They also include an internal adapter for the 30mm blocking filter which seems interesting and the price is a few bucks cheaper than a FT. I also found that Rigel makes a motorized device for the helical which I'm going to try out before I spend the big $$ on a new focuser.

Re: Helical to Feather Touch SMII

Posted: Mon May 11, 2020 12:22 am
by DeepSolar64
In time I will replace both of mine with either Moonlite or FeatherTouch focusers. I understand Coronado using the helical focusers to keep the price down but I would have preferred even a cheap rack-and-pinion focuser over the helical. You have to fiddle around too much with them to get a precise focus.

James

Re: Helical to Feather Touch SMII

Posted: Mon May 11, 2020 6:09 am
by Rusted
Just in case anybody thinks a posh focuser is ABSOLUTELY essential to their solar observing:
It's not.Well, not always.

A "serial" FT quality focuser might be nice.. for its looks.
But what about a mid-system, entirely tubular, plug-in and socket-out arrangement?
i.e. No flange or ring-type, rotating, slipping clutch, adapter FT system.
The adapter rings alone cost as much as some telescopes!

The problem is that needs a much larger [telescope side] socket.
To allow the drawtube to pass freely in and out inside it.
So now it won't fit inside our AOK Swiss etalon adapter. :shock:

Some solar telescopes don't need a conventional focuser on the backplate/tailpiece. Our PST mods!
The vital optics are fixed. No need to move them at all. Makes things worse if you do!
Once set, they might as well be welded in place. Except for occasional access for cleaning of course.

FT R&P focusers are built seriously heavy for stability and precision.
The drawtube is half an inch thick on the big guys like my 3.5".
Handy and highly cosmetically desirable [for balance!] if you have very nose heavy [APO?] refractor.

Do we really need all that weight on the end of an already extended tailpiece?
It would add seriously to the "moment" if it were placed mid stream in an extended filter stack.

After fiddling about with floppy 1.25" helical focusers I found an inexpensive 2".
A long throw, 20mm travel, which is holding up really well.
It fits the AOK Swiss etalon adapter perfectly on the telescope side.
While a threaded socket on the tail end safely houses the vital blocking filter.
And yes, I do know there are other kinds of solar telescopes than PST mods. ;)
P1410920 rsz 600.JPG
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Re: Helical to Feather Touch SMII

Posted: Mon May 11, 2020 6:14 am
by marktownley
My advice would be to get the Feather touch over the Moonlite. Both are great and i've got over two decades experience of using both, but with time the bearings fail on the Moonlites which is a PITA, Moonlite replace them, but they don't all fail at the same time.

Re: Helical to Feather Touch SMII

Posted: Mon May 11, 2020 11:52 pm
by hopskipson
marktownley wrote: ↑
Mon May 11, 2020 6:14 am
My advice would be to get the Feather touch over the Moonlite. Both are great and i've got over two decades experience of using both, but with time the bearings fail on the Moonlites which is a PITA, Moonlite replace them, but they don't all fail at the same time.
How long before the bearings failed Mark?
I like the pricing of the moon lite. I can get it with a stepper motor for the same price as the ft. I also have the 30 mm blocking filter. Moonlite makes an adapter to locate it on the focusing tube. Also you can get it in gold anodized with 2 finder adapters at no extra charge 😁.

Re: Helical to Feather Touch SMII

Posted: Tue May 12, 2020 12:06 am
by hopskipson
DeepSolar64 wrote: ↑
Mon May 11, 2020 12:22 am
In time I will replace both of mine with either Moonlite or FeatherTouch focusers. I understand Coronado using the helical focusers to keep the price down but I would have preferred even a cheap rack-and-pinion focuser over the helical. You have to fiddle around too much with them to get a precise focus.

James
For purely visual purposes it is not bad. But the weak links are the draw tubes. They sag and I don’t trust them and only 1.25” ?
Imaging is a whole different thing . I’m getting a cheap motor focus system temporarily until I can save up the money.

Re: Helical to Feather Touch SMII

Posted: Tue May 12, 2020 6:01 am
by marktownley
hopskipson wrote: ↑
Mon May 11, 2020 11:52 pm
marktownley wrote: ↑
Mon May 11, 2020 6:14 am
My advice would be to get the Feather touch over the Moonlite. Both are great and i've got over two decades experience of using both, but with time the bearings fail on the Moonlites which is a PITA, Moonlite replace them, but they don't all fail at the same time.
How long before the bearings failed Mark?
I like the pricing of the moon lite. I can get it with a stepper motor for the same price as the ft. I also have the 30 mm blocking filter. Moonlite makes an adapter to locate it on the focusing tube. Also you can get it in gold anodized with 2 finder adapters at no extra charge 😁.
Mine all started to go after a couple of three years of use. Don't get me wrong, the Moonlites are really nice, and certainly offer nice features, and I don't think you will be disappointed at all. It's a bit like having a favourite 18 year old single malt whisky, you've enjoyed it for years then a friend comes along with the 21 year old age statement of it - game over then!

Re: Helical to Feather Touch SMII

Posted: Tue May 12, 2020 7:02 am
by DeepSolar64
The drawtubes and helical focusers just don't feel natural when you are used to using either rack and pinion or Crayford focusers on nighttime scopes. They are useable but take some getting used to. Fine focusing is a bit difficult. Mark, what do you think of the drawtubes and helical focusers on the Coronados? Not the best I am sure. You replaced them with the FeatherTouch. Is replacing them difficult? Changing the focusers out?

James

Re: Helical to Feather Touch SMII

Posted: Tue May 12, 2020 11:06 am
by marktownley
I wasn't a fan of the coronado helicals, they work, but are agricultural at best. Changing the focusers is doable but can be difficult, Coronado is a great fan of loctite / thread lock, and everything on these scopes screws together. It can be unscrewed but takes a lot of brute force, possibly heat and boa grips.

Re: Helical to Feather Touch SMII

Posted: Tue May 12, 2020 4:52 pm
by DeepSolar64
marktownley wrote: ↑
Tue May 12, 2020 11:06 am
I wasn't a fan of the coronado helicals, they work, but are agricultural at best. Changing the focusers is doable but can be difficult, Coronado is a great fan of loctite / thread lock, and everything on these scopes screws together. It can be unscrewed but takes a lot of brute force, possibly heat and boa grips.
WoW, and you don't wanna mar the tube by putting it in a vice.

Re: Helical to Feather Touch SMII

Posted: Wed May 13, 2020 11:16 am
by Rusted
DeepSolar64 wrote: ↑
Tue May 12, 2020 4:52 pm
marktownley wrote: ↑
Tue May 12, 2020 11:06 am
I wasn't a fan of the coronado helicals, they work, but are agricultural at best. Changing the focusers is doable but can be difficult, Coronado is a great fan of loctite / thread lock, and everything on these scopes screws together. It can be unscrewed but takes a lot of brute force, possibly heat and boa grips.
WoW, and you don't wanna mar the tube by putting it in a vice.
Quite. Putting a tube in a vice only makes matters worse.
Because it becomes oval and greatly increases the friction.

A Boa clamp/strap works mostly by evenly spreading circumferential friction.
The trick is to use a pair of them opposed to each other. If you can.

I had literally hours of exhausting "fun" dismantling my PST.
Even using extension tubes on the boa handle for more leverage.
This also contained the rubber strap. Instead of allowing it to escape sideways from its slot.

I didn't dare use heat in case I broke something important.
But almost broke the Boa strap in my struggle!

Re: Helical to Feather Touch SMII

Posted: Wed May 13, 2020 2:25 pm
by marktownley
Rusted wrote: ↑
Wed May 13, 2020 11:16 am
But almost broke the Boa strap in my struggle!
Oh i've gone through a few boas :D :D :D

Re: Helical to Feather Touch SMII

Posted: Wed May 13, 2020 5:28 pm
by Solar B
You havn't lived unless you've been through a few boa's πŸ˜…

Last time my mate was using a car oil filter wrench constrictor on his & my PST

Brian

Re: Helical to Feather Touch SMII

Posted: Wed May 13, 2020 5:32 pm
by DeepSolar64
WoW, Coronado obviously does not want them to come loose.

Re: Helical to Feather Touch SMII

Posted: Wed May 13, 2020 6:43 pm
by marktownley
DeepSolar64 wrote: ↑
Wed May 13, 2020 5:32 pm
WoW, Coronado obviously does not want them to come loose.
It's going to take more than a bit of loctite to stop us solar chatters ;)

Re: Helical to Feather Touch SMII

Posted: Mon May 18, 2020 12:52 am
by hopskipson
IMG-2876.jpg
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I contacted Leon at Rigel (nstep motor focus) and he had made one of these for a client. It should help with focusing for imaging. Now I need a motorized etalon adjuster. Has anyone done something for that?
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Re: Helical to Feather Touch SMII

Posted: Mon May 18, 2020 1:20 am
by DeepSolar64
An electronic focuser I presume? That would be neat. I love the binoviewer too. I gotta get one of those!

Re: Helical to Feather Touch SMII

Posted: Mon May 18, 2020 10:44 pm
by hopskipson
DeepSolar64 wrote: ↑
Mon May 18, 2020 1:20 am
An electronic focuser I presume? That would be neat. I love the binoviewer too. I gotta get one of those!
You Definitely gotta get binos! It’s like 3D viewing.

I’m going to try out the motor focuser when I do imaging once I get the tuning down. I think it’s only a temporary solution. The draw tubes seem to sag and they are only 1.25” otherwise this is a great scope.