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Stellarvue AT1010 - what is the thread at the end of the focuser drawtube ?

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#1 bridgman

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Posted 16 March 2019 - 11:04 PM

I just realized that even after nearly 20 years my SV AT1010 is still pretty much perfect other than the eyepiece holder at the end of the focuser drawtube, which has only the most tenuous hold on the diagonal. It's still my most-used scope, and now that I finally have a decent alt-az mount (2 of them actually, although one of them is afraid of the cold which is a problem in Canada) it seems like a perfect grab & go scope.

 

It has a 2" focuser but fixed dew shield. I would have purchased it new some time around 2000 or 2001. The end of the drawtube has male threads, just under 2.2", and what seems to be 1mm pitch. To me that suggests M56x1 thread, but all the references to M56x1 thread talk about Synta and Celestron while AFAICS the AT1010 had a GSO focuser.

 

If I can get reasonable confidence that I'm measuring the threads correctly (I'll go digging around in the basement tomorrow in search of my vernier calipers) I'm thinking about adding either a ScopeStuff adapter or a Baader click-lock. This whole thing started when diagonal+eyepiece nearly fell out for the 53rd time and I thought "**** I need a Rotolock on the end there".

 

http://www.scopestuff.com/ss_fas2.htm

https://www.firstlig...skywatcher.html

 

IMG 20190316 235952
 
BTW I have been looking for nylon-tipped replacements for the M3 eyepiece screws but they seem pretty hard to find... nylon screws are easy but M3 seems a bit small for nylon screws and big heavy diagonal+eyepiece.
 
And yes I should probably un-tape that allen key from the side of the focuser but I'm leaving it there until I at least figure out what it fits. I'm starting to think it was taped there just to drive me crazy.

 

Thanks,

John


Edited by bridgman, 16 March 2019 - 11:22 PM.

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#2 Jon Isaacs

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Posted 16 March 2019 - 11:56 PM

BTW I have been looking for nylon-tipped replacements for the M3 eyepiece screws but they seem pretty hard to find... nylon screws are easy but M3 seems a bit small for nylon screws and big heavy diagonal+eyepiece.

 

What I have done is just re-tap the threads to a larger size.  I like 8-32 brass thumb screws.  TeleVue used 10-32 aluminum thumbscrews.  

 

I believe you are correct, the scope is basically GSO so the exact fit maybe difficult, very few GSO refractors were ever made.  another option would be to upgrade the focuser to a GSO Crayford.

 

Jon



#3 bridgman

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Posted 17 March 2019 - 12:59 AM

Never thought about re-tapping but it makes a lot of sense.

 

EDIT - the replacement focusers turn out to be less pricey than I expected... ScopeStuff has a good selection. Replacing the focuser would probably be the smart/safe decision, but I would rather keep the scope as close to stock as possible.

 

I went ahead and ordered the Baader M56 click-lock so hoping the thread on the end of the tube really is M56. Only concern is that ScopeStuff used to sell a separate adapter specifically for the Stellarvue scopes - now discontinued but if the M56 thread is correct then I would have expected a link to the Synta adapter above - SS is pretty good about cross-referencing.


Edited by bridgman, 17 March 2019 - 12:56 PM.

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#4 archy990

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Posted 17 March 2019 - 06:12 PM

Nice to see another Stellarvue AT1010 still in action! mine is from 2003. It's now my guidescope, and I love it dearly!

 

Jeff''s Astro Rig

 

All the best,

 

Jeff

Madison, WI


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#5 bridgman

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Posted 18 March 2019 - 01:49 AM

That's a great looking setup... and it's nice to see the AT1010 as part of it. 

 

The AT1010 is still my most-used scope. Still see quite a few of them around here - it's even the workhorse scope for club borrowing:

 

https://rascto.ca/co...80-mm-refractor

 

I was using the SV for guiding on a dual-saddle setup, but since the rings didn't have tapped holes on top I hadn't thought about mounting the AT72 on top of it. Did you find replacement rings that fit the tube ?

 

EDIT - I guess if the focuser size is standard then maybe the tube OD is standard as well - 90mm maybe.

 

second EDIT after D'oh!! moment - I bet those are going to turn out to be Stellarvue's standard 90mm rings and I'm going to feel stupid confused1.gif

 

https://www.stellarv...ng-set-r090set/


Edited by bridgman, 18 March 2019 - 10:08 AM.

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#6 archy990

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Posted 18 March 2019 - 10:41 AM

Second EDIT after D'oh!! moment - I bet those are going to turn out to be Stellarvue's standard 90mm rings and I'm going to feel stupid confused1.gif

 

https://www.stellarv...ng-set-r090set/

Bingo! The rings are Stellarvue's standard 90mm rings. Terrific quality of course, and a nice array of tapped holes on top. :-D

 

J



#7 bridgman

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Posted 18 March 2019 - 01:34 PM

Like so many things in life that makes perfect sense in hindsight confused1.gif 

 

Armed with this new knowledge, I guess I should have ordered new rings for my AT1010 and mounted the AT72EDII on top of the AT1010 rather than ordering SV riser blocks for the 72mm and trying to cobble together a guidescope using camera lenses.

 

Thanks for the great pic and information... it really helps despite my whining about the consequences.


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#8 bridgman

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Posted 04 April 2019 - 04:06 PM

Sigh... so close.

 

Good news - after disappearing into limbo between Royal Mail and Canada Post for a couple of weeks the M56 ClickLock arrived. Apparently having shipments disappear like that is common but they always show up eventually. Not sure of the specifics but apparently Canada Post no longer provides tracking info via their web site even though they still track it themselves and provide delivery confirmation back to Royal Mail.

 

Bad news - it doesn't fit. The thread on the end of the AT1010 focuser drawtube is just a tiny bit bigger than the M56 female thread on the ClickLock, which leaves me a bit baffled re: what the thread could be. The pitch appears to be metric but it's maybe a millimeter bigger than M56. I didn't think there was such a thing as M57 and it definitely seems smaller than M56... and I'm sure there's no such thing as 2.25" x 1mm thread, or at least there shouldn't be.

 

The ClickLock *is* very nice though, almost worth buying a scope that it does fit laugh.gif

 

EDIT - after some more digging around I found that there *is* an M57 accessory thread, associated with both Borg and Lomo, although I'm not sure if they are both M57x1mm. Anyways, I have finally done what I should have done at the start and asked Stellarvue for guidance.

Attached Thumbnails

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Edited by bridgman, 04 April 2019 - 05:05 PM.

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#9 dmorrow

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Posted 05 April 2019 - 05:08 AM

You could try contacting Stellarvue, they are very responsive.

2nd a good GSO dual-speed focuser, I put one on my c80 and loved it! I just kept the stock focuser and put it back in when I sold it.

#10 bridgman

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Posted 07 April 2019 - 09:59 AM

Yep, waiting to hear back from SV. With those "contact" web pages I'm never sure if the message was actually sent though...

 

I was hoping to avoid replacing the focuser... someone obviously worked hard to make the stock one good and I hate replacing it just because I don't get along with the (removable) visual back, but at the moment either replacing the focuser or re-tapping the thumbscrew holes is starting to seem like the only option. I had a brief hope that one of the Borg M57 adapters might work but it appears their M57 is 0.75mm pitch rather than what seems to be 1.0mm pitch on the focuser.

 

Still haven't totally given up hope on finding a <whatever is on the focuser> to <something that Baader makes a Clicklock for> adapter but getting close frown.gif

 

EDIT... just discovered "Precise Parts" so maybe there is still hope... also GSO appears to still be offering the focuser so there may be some kind of aftermarket for it.

 

https://www.precisep...ain//index.html

 

http://www.gs-telesc...tent.asp?id=139

 

The Build-an-adapter page at Precise Parts even lists the Baader M56 ClickLock as an option for the camera end... but not the AT1010 focuser for the telescope end. If I can just figure out how to get the right thread entered in the telescope end I'm set. Yes it will probably end up costing almost as much as a new focuser but I like the current focuser and I like the ClickLock laugh.gif


Edited by bridgman, 07 April 2019 - 10:59 AM.


#11 bridgman

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Posted 12 May 2019 - 09:07 PM

Bleah... I might have to cross my fingers, hope that I measured everything correctly, and order an M57->M56 adapter from PreciseParts. I pinged SV a few times with no response... guessing I might have more success by phone.

 

After measuring the drawtube, visual back and ClickLock it seems that another option should be getting an M56x1 die and turning the M57 thread down to M56, but an M56x1 die seems to be even harder to find than a visual back for the AT1010.

 

Tried removing the existing focuser to check outside dimension for a replacement focuser but seems like it was either glued in or pressed in... short of wailing on it with a sledge hammer or maul the focuser does not seem to be interested in coming out of the tube.

 

EDIT - and yes, re-tapping the existing visual back to take 8-32 or 10-32 screws is looking better with every passing week. I have some doubts about whether replacing the 2 existing screws with larger ones will be sufficient, but I guess adding a third screw should help as well. The twist/click/roto lock holders are just so nice though. Looks like the existing thumbscrews are M4 which IIRC is about the same size as 8-32, so looks like I would need to go up to 10-32 at minimum.

 

I suppose another option would be to get an adapter that slips into the 2" visual back and takes the M56 rotolock on the other end, and then replace the M3 thumbscrews with a few self-tapping metal screws to fix it in place permanently laugh.gif

 

Anyways, I have contacted PreciseParts re: adding an M57x1 thread for AT1010 drawtube to their database (I might get lucky and find that GSO uses the same thread for their projection eyepieces although forum gossip suggests M57x0.75 is more likely)... guess I'll see where that goes.


Edited by bridgman, 12 May 2019 - 10:21 PM.


#12 bridgman

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Posted 10 April 2020 - 03:43 PM

I have contacted Stellarvue and GSO again about the thread pitch - I didn't feel up to risking the $$ for a custom adapter without a bit more confirmation. In the meantime I took a hacky approach and ordered up a 2" nosetube with M56 thread on the end, which if I guessed right should thread into the M56 ClickLock I ordered previously:

 

https://www.firstlig...ducers.html#faq

 

These adapters seem to be popular but are normally used with a ClickLock "the other way round", ie M56 ClickLock threads onto the end of the focuser drawtube, adapter fits into the ClickLock, then M56 reducer threads onto the adapter allowing rotation and exposing M48 filter threads. I'm going to try putting the adapter into the AT1010 visual back then threading the M56 ClickLock onto the adapter.

 

I got curious about how much bearing surface there would be to keep the adapter aligned so took a look into the focuser drawtube to see if the inside of the tube happened to be 2" ID like the visual back (no, more like 2-1/8"). What I also saw was that a piece of plastic had come loose and was stuck at an angle in the drawtube. That probably explains the less-than-inspiring views last time I took the scope out. I was playing hide-and-seek with cloud cover but still couldn't understand why I was having so much trouble even getting a good view of the moon. Figured if the seeing was that bad it wasn't worth bringing out the AT115. D'oh !!

 

I pushed the plastic piece back to the end of the drawtube, guessing at orientation, then kicked myself for not measuring the inside diameter of the hole before doing so. I normally measure everything. Doing some very crude measurement using the picture I get somewhere around 34-35mm, which seems to make it more likely to be acting as a baffle rather than a mask.

 

Anyways, now that I have a fallback plan I figure it's more likely that someone at either Stellarvue or GSO will remember what the thread is. GSO appears to still be selling the focuser so there's hope.

 

EDIT - yes, the view through the scope is much better now that plastic piece is back where it belongs (thank you Captain Obvious). I guess that explains why I was having such a tough time getting my new laser aligned with the scope tube as well. Instead of a dot or a line (it was a bit foggy) all I was seeing was a series of rings. Now I see a nice tight dot.

 

Also just noticed that Agena has something similar to the adapter I ordered, although it's a two part solution while I believe the one from FLO is one piece:

 

https://agenaastro.c...enses-m-06.html

 

BTW I realize that even with the ClickLock I will still be dependent on how well the original visual back holds onto the diagonal AND I have added another set of threads that could come loose, but the main thing that bugged me about the original visual back was that I really had to cinch down the screws in order to have any chance of it holding and didn't want to have to keep doing that every time I changed accessories. I can always drill a couple of partial holes in the adapter tube to keep everything in place.

 

Does anyone ever use blue Loctite on optical threads ?

Attached Thumbnails

  • IMG_20200410_163001.jpg

Edited by bridgman, 11 April 2020 - 12:40 PM.


#13 bridgman

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Posted 18 April 2020 - 09:10 PM

OK, I finally found something inexpensive that I could use to confirm whether or not the focuser thread really is M57x1:

 

https://www.ebay.com...em=223508172775



#14 bridgman

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Posted 09 May 2020 - 03:53 PM

No progress on identifying the mystery thread, but the M56 adapter arrived from FLO so I can finally use the M56 ClickLock on the ATI1010. It's not a perfect solution because it still depends on the stock visual back, but at least now I only have to crank down the VB screws on the new adapter once and can use the ClickLock from that point on.

 

Yes it is possible that I am being a bit stubborn about this :D

 

First pic shows the 2" nosepiece with M56x1 thread on the right, second pic shows everything fitted together:

Attached Thumbnails

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  • IMG_20200509_164626.jpg

Edited by bridgman, 09 May 2020 - 03:54 PM.


#15 deepwoods1

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Posted 11 May 2020 - 07:46 AM

Be wary, that little plastic piece will dislodge again. I spoke with Vic a couple of years back and was informed just to remove it. I was thinking about painting the inside of the focuser black to control reflections, but haven’t noticed a difference at my visual end. It is a great scope! 



#16 bridgman

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Posted 21 May 2020 - 06:44 PM

Be wary, that little plastic piece will dislodge again. I spoke with Vic a couple of years back and was informed just to remove it.

Good to know... thanks !

 

OK, I finally found something inexpensive that I could use to confirm whether or not the focuser thread really is M57x1:

 

https://www.ebay.com...em=223508172775

The adapter arrived today, and the M57x1 side threaded cleanly onto the end of the focuser drawtube... so I think we finally have an answer.

 

Thanks for all the good ideas along the way.


Edited by bridgman, 21 May 2020 - 06:44 PM.



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