Threads on Solarmax 60 mm External Etalon

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kornfeld1
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Threads on Solarmax 60 mm External Etalon

Post by kornfeld1 » Tue Jul 03, 2012 2:52 am

I received my Solarmax 60 mm external etalon today, and thought I'd post up the specs on the threads. There are actually two sets of threads on the rear of the etalon assembly--an inner set and an outer set. Here's how that looks:



The area circled in red shows the inner threads; the area circled in blue shows the outer threads.

The internal set of threads is M77x0.75. The external set of threads is M82x0.75. I read in multiple places that the thread pitch was actually 1.00, but I took the etalon by a machine shop to ask about having an adapter made, and the guy measured each side with a thread gauge and said they were 0.75. The outer threads look more coarse than the inner threads to me, so he might have been wrong, but my eye might be wrong as well!

One final note: I'm not quite sure how to word this, bu there are more threads on the inside than on the outside. What I mean here, is that if you run your fingernail over the threads, you'll count three threads on the outside and six threads on the inside.

I was looking for this information prior to purchase, and found several threads with the question asked but mixed answers, so I figured I'd post this up here.
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Re: Threads on Solarmax 60 mm External Etalon

Post by Merlin66 » Tue Jul 03, 2012 11:02 am

Thanks for adding that to our "technical database"....
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Re: Threads on Solarmax 60 mm External Etalon

Post by rbotero » Tue Jul 03, 2012 1:27 pm

Wow, thanks for posting this. I am having an adaptor made to couple my DS SM60 unit to the front of a 70mm semi-apo. I measured the threads using a vernier and got 1mm...but it could be wrong if your guy used a thread gauge...

I'm confused - I had read in other places the pitch was 1mm and assumed my measurement was right!
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Astro-Physics Starfire EDF 152mm f/7.5, TEC MC 250mm f/10 22% CO, Polarex 75mm f/16 #132C, Questar 3.5" Standard (1960) and Duplex (1991), Coronado SolarMax DS 60mm f/6, Ikharos ED 70mm f/6
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Re: Threads on Solarmax 60 mm External Etalon

Post by rbotero » Tue Jul 03, 2012 1:45 pm

I'm getting a thread gauge now!
Roberto Botero

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Astro-Physics Starfire EDF 152mm f/7.5, TEC MC 250mm f/10 22% CO, Polarex 75mm f/16 #132C, Questar 3.5" Standard (1960) and Duplex (1991), Coronado SolarMax DS 60mm f/6, Ikharos ED 70mm f/6
Astro-Physics AP900GTO CP3, Vixen Super-Polaris, Linhof R-Stativ
ZWO ASI120MM for guiding, solar and planetary imaging, SXVR-H18 + SX CFW + SX OAG + Baader LRGB Ha OIII SII filters
Baader Herschel solar wedge, Mark IV binoviewers, Mark III Zooms

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Re: Threads on Solarmax 60 mm External Etalon

Post by Merlin66 » Tue Jul 03, 2012 3:03 pm

According to my thread gauge, and 45 years engineering experience, the external thread on the SM60 filter has a pitch of 1mm.
(The SM40 filter....well that is the same as the "standard" photographic filters - 0.75mm)
I hope this concludes the discussion!!
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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Re: Threads on Solarmax 60 mm External Etalon

Post by kornfeld1 » Tue Jul 03, 2012 3:24 pm

Merlin, can you measure the internal threads as well? Like I said in my first post, those do look more fine than the outer threads...but that's just me eyeballing it.
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Re: Threads on Solarmax 60 mm External Etalon

Post by kornfeld1 » Tue Jul 03, 2012 3:29 pm

Wow, thanks for posting this. I am having an adaptor made to couple my DS SM60 unit to the front of a 70mm semi-apo. I measured the threads using a vernier and got 1mm...but it could be wrong if your guy used a thread gauge...

I'm confused - I had read in other places the pitch was 1mm and assumed my measurement was right!

I used a set of digital calipers as well to try and measure the threads, and to be honest, I couldn't really tell much difference between when they were set to 1.00 mm and when they were set to 0.75 mm. It was tough to hold them up to the threads and be really confident in what I was seeing.
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Re: Threads on Solarmax 60 mm External Etalon

Post by Merlin66 » Tue Jul 03, 2012 3:34 pm

Kornfeld,
I'd love to help further, but my astronomomical gear (and all the household stuff!!) is in the process of being packed for shipment back to Australia.
I have access to the actual adaptor plates I made up for the ED80, but not to the SM60 filters themselves...to break them out of the shipping containers would be too much at the moment! Someone else will have to confirm the inside thread dimensions....
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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Re: Threads on Solarmax 60 mm External Etalon

Post by rbotero » Tue Jul 03, 2012 3:42 pm

Thank you Ken! :thanx:

Kornfeld, I have bought the thread gauge to measure this myself (only £10 or so) but I'm pretty confident after Ken's post. I have seen the pitch quoted as 1mm on CN and Stargazerslounge before so hopefully that settles it. But you are right, it's difficult to tell the difference even when using a good caliper... :pinch:

Roberto
Roberto Botero

Kent, UK


Astro-Physics Starfire EDF 152mm f/7.5, TEC MC 250mm f/10 22% CO, Polarex 75mm f/16 #132C, Questar 3.5" Standard (1960) and Duplex (1991), Coronado SolarMax DS 60mm f/6, Ikharos ED 70mm f/6
Astro-Physics AP900GTO CP3, Vixen Super-Polaris, Linhof R-Stativ
ZWO ASI120MM for guiding, solar and planetary imaging, SXVR-H18 + SX CFW + SX OAG + Baader LRGB Ha OIII SII filters
Baader Herschel solar wedge, Mark IV binoviewers, Mark III Zooms

kornfeld1
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Re: Threads on Solarmax 60 mm External Etalon

Post by kornfeld1 » Wed Jul 04, 2012 6:57 pm

Kornfeld,
I'd love to help further, but my astronomomical gear (and all the household stuff!!) is in the process of being packed for shipment back to Australia.
I have access to the actual adaptor plates I made up for the ED80, but not to the SM60 filters themselves...to break them out of the shipping containers would be too much at the moment! Someone else will have to confirm the inside thread dimensions....

Well I suppose if everything is being packed up for an international move, you've got a valid excuse for not measuring them. ;)

I really think the inner threads might be 0.75 pitch though. I bought a regular ol' camera adapter that threads onto the inner threads, and almost everything I've read says that standard camera adapters at that size have 0.75 pitch threads. Unfortunately, there wasn't any info on this on the packing for the adapter I bought, so I can't be sure.
DMK41---Sold

Solarmax 60 and BF15 on a 900 mm Refractor---Sold

Upgraded Coronado PST----Sold

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Re: Threads on Solarmax 60 mm External Etalon

Post by Solarhound » Fri Jun 20, 2014 7:15 pm

This thread was just brought to my attention so I have done this to varify the pitch of these threads , hope this clears any confusion .
p1.jpg
p2.jpg

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Re: Threads on Solarmax 60 mm External Etalon

Post by marktownley » Fri Jun 20, 2014 9:05 pm

might have to get me one of these thread gauge thingies, they look good!

I'm going to move this to the library section, I think it belongs better in there :)
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