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Guide-scope on custom CNC-machined Side-by-Side & in-line setups

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#1 B 26354

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Posted 28 June 2019 - 08:39 PM

Guide-scope on custom CNC-machined Side-by-Side & in-line setups


Part One:


Starfleet Astrosystems - C-N Review 001.jpg


Starfleet Astrosystems - C-N Review 002.jpg


One year ago, I posted some comments in this thread:




...about my fruitless search for some 63mm ID clamshell rings, for a 60mm APM guide-scope that I intended to purchase sometime in the ensuing six months, along with a Lacerta M-GEN II auto-guider. At that time, using an ES 102CF refractor on an iOptron CEM25P EQ mount, the limited amount of astro-photography I had done had all been 30-second unguided subs, and I was becoming interested in finding the means to attempt longer, guided exposures.


However... having spent countless hours reading threads about the various flexure issues associated with guide-scope mounting, I felt that perhaps a significant contributor to that flexure was the generic use of dual three-point mounting rings, the vast majority of which utilize plastic- or nylon-tipped positioning-screws. To me, the logical solution was to simply use a pair of "clamshell" rings, instead.


Unfortunately, as I'd explained in my post, I'd been unable to find any commercially-made clamshells that were the necessary 63mm in diameter.


A few days after I'd submitted that post, C-N member Anurag Shevade -- who resides in Mumbai, India -- PM-ed me, explaining that in his spare time, he liked to design and fabricate CNC-machined parts for astronomical instruments, and hoped at some point to become a vendor of such. He further explained that he happened to be using the same APM guide-scope that I was going  to buy, and that it had been his intention to make clamshell rings for his own scope. He offered to make a pair for me, as well... based on the mutual understanding that due to a variety of circumstances, it might well be six months or more, before the rings would arrive at my door.


As things turned out, I didn't take possession of the guide-scope or guide-camera until this past February, and I received the clamshell rings shortly thereafter. In the interim, Mr. Shevade had finalized his own wishes, and had become an authorized vendor, doing business on Cloudy Nights and in the public domain as "Starfleet Astrosystems".


Having maintained communications throughout the intervening months, the contents of my initial order had grown considerably... the end result of which, is that I now have an incredibly versatile system of mounting-accessories that enable the effortless and tool-less setup of the APM guide-scope on either a customized inverted-Vixen handle on the ES 102CF refractor, or on a custom CNC-machined side-by-side setup with a Stellarvue SV70T.


An initial complicating factor in having Mr. Shevade design the clamshell rings, involved deciding where and how to mount them on the ES refractor... realizing that at some point in the future, I may have other scopes on which I'd also want to mount the guide-scope. It was at this point that it became obvious to me that his work-ethic is one of full and unlimited cooperation and collaboration with his customers. Over the course of the ensuing months, my initially simple "setup" became a full-fledged "system"... the basis for the design of each custom CNC-machined element being a series of fully collaborative discussions between us, consisting of my needs and desires, combined with Mr. Shevade's incredible ingenuity and engineering expertise.


The final results of this enjoyable and rewarding process are shown in the initial photographs, above. The details of the separate pieces, and the logic behind their design and arrangements, will be shown in the remainder of this multi-part thread.

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#2 B 26354

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Posted 28 June 2019 - 08:44 PM

Part Two:


As explained, my initial desire was to simply but very solidly mount the APM guide-scope onto my ES refractor, using a pair of custom-made clamshell rings. Rather quickly, though... two other design factors demanded attention.


Firstly... in thinking about where and how to mount the guide-scope, there were several "balance" issues that needed to be addressed.


In the past, one of the things that had been making me crazy about setting up and working my way through an AP session, was the way in which the weight of the ES refractor's axially-offset finder-scope made it impossible to arrange the mount's counterweights such that the scope would remain balanced in every position in which it was placed. Every new target-position required the setup to be re-balanced.


The obvious solution for the guide-scope's placement, was to put it on the refractor's handle, which would position it directly in line with the mount's declination axis. But with the stock handle being just a very rounded, cast aluminum piece... it didn't seem that bolting the clamshell rings onto it would be as solid of an affair as I felt was necessary. Also, that sort of attachment would preclude my being able to easily remove the guide-scope and place it on a different AP setup, without the use of tools.


Designed and CNC-machined by Mr. Shevade, two 1"x1"x1.5" riser blocks and a smoothly CNC-machined inverted Vixen rail replaced the handle... and along with a set of 1"-long Vixen mini-clamps for the bottom of the rings, they provided exactly what was needed.


Starfleet Astrosystems - C-N Review 003.jpg


But what about that pesky off-kilter finder-scope?


Well... by the time I’d started seriously looking into ways to fix the finder-induced balance issues for the ES refractor, I'd also gotten a Stellarvue SV70T, so Mr. Shevade and I had begun devising a side-by-side system for the guide-scope and the Stellarvue refractor -- which didn't have a finder.


Not wishing to purchase a second finder for the SV70T... the straightforward solution actually ended up being fairly simple.


The APM guide-scope had come with its own set of "three-point" rings on a short Vixen rail... so I removed the finder-bracket and finder from the ES refractor, and put the finder in the APM rings:


Starfleet Astrosystems - C-N Review 004.jpg


This way, with a second set of Mr. Shevade's Vixen mini-clamps bolted onto the top of the guide-scope rings, I can effortlessly attach or remove the finder from either the ES refractor or the Stellarvue side-by-side system, whenever necessary, without tools.


Starfleet Astrosystems - C-N Review 005.jpg


Starfleet Astrosystems - C-N Review 006.jpg


Starfleet Astrosystems - C-N Review 007.jpg

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#3 B 26354

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Posted 28 June 2019 - 08:48 PM

Part Three:


What's great about this system, is that it allows me to completely remove the finder when it's not needed. So the finder isn't realistically a part of the AP setup, at all... and when I’m actually taking photographs, the finder won’t ever be on it. I'll only be using it, if necessary, to visually locate my targets. Meaning that -- best of all -- I can balance each of the AP setups, without the finder.


Starfleet Astrosystems - C-N Review 008.jpg


Starfleet Astrosystems - C-N Review 009.jpg


Problems solved!


Starfleet Astrosystems - C-N Review 010.jpg


Among other features of the beautifully-machined clamshell rings, sharp-eyed enthusiasts will notice that there is very little clearance between the rings and the guide-scope tube. This is completely on purpose, and is a part of Mr. Shevade's design philosophy. It had struck me that even clamshell rings have a potential source for OTA flexure, in the felt linings on the rings. However... as opposed to the 2- or 3mm-thick felt that is typically used for this purpose -- like that on the Stellarvue and ES refractors' rings -- the felt on Mr. Shevade's rings is less than 1mm thick.


The expression "solid as a rock" immediately comes to mind.


I should probably also point out, if it isn't already obvious, that all of these CNC-machined pieces are hard-anodized. My personal choice was to have everything done in black... but some of you may be pleased to learn that other colors are also available.

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#4 B 26354

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Posted 28 June 2019 - 08:53 PM

Part Four


Owners of Stellarvue refractors may also notice that while the SV70T's stock clamshell rings are mounted on a Stellarvue Vixen rail, they are not sitting on the 2.5"-tall, 3"-wide riser-blocks that are available from Stellarvue... the combined weight for two of which, is 21 ounces, not counting the requisite mounting-bolts. Instead, the rings sit on a second set of 1"x1"x1.5" riser blocks, again made by Starfleet Astrosystems.


Starfleet Astrosystems - C-N Review 011.jpg


Along with one of Mr. Shevade's 8" vixen rails, the side-by-side system includes a custom-designed 14" Vixen dovetail and a 5"-long custom-machined one-piece Vixen clamp, engineered to provide maximum strength and flexure-resistance while holding the SV70T/camera combination. Had I wanted a "non-marring", movable-sided clamp, he could easily have made one. My preference was for a clamp that would provide maximum rigidity, in spite of the potential for a few "unsightly" scratches that will inevitably appear in the clamped rails, with prolonged use.


Starfleet Astrosystems - C-N Review 012.jpg


One additional feature about Mr. Shevade's dovetail rails that I'd like to point out, is that he always provides a threaded hole near each end of the rails, as provision for the placement of a "stop-bolt". I was quite pleased to discover that he does this, as I have been putting stop-bolts on all of my camera tripod mounting-plates for more than five decades... and from the moment that I began using Vixen-type rails for mounting my astro-optics, if I found that a dovetail didn't already have a stop-bolt hole, I've always made certain to drill and tap one. Watching a multi-thousand-dollar optical setup drop onto my concrete driveway because I failed to properly tighten a clamp, and there wasn't a stop-bolt on the rail to prevent its fall... is not a phenomenon that I ever want to experience.


Also... while always striving for "reasonable" weight savings and structural versatility when designing components such as these, it is Mr. Shevade's contention that strength and rigidity are paramount. As such, extraneous weight-reduction holes are kept to a minimum, unless requested by the customer... and personally, I find the solidity of these setups to be remarkable.


And regarding overall weight... a final aspect of these two separate AP setups came as a delightful surprise. While going through the various planning stages involved with creating the side-by-side setup, I was curious (and concerned) about how much the finished, AP-ready setup would weigh.


In its new arrangement, the ES 8x50 Finder, with its new rings and mini Vixen-dovetail, weighs 1.4 lb.


As pictured at the beginning of this thread....


The ES 102CF refractor, in its complete AP setup (without the finder), weighs 14.4 lb


The Stellarvue SV70T refractor, in its complete AP setup (without the finder), weighs 14.2 lb


So both AP setups come in at almost exactly half of the iOptron CEM25P's rated payload capacity.




Starfleet Astrosystems - C-N Review 013.jpg


Again, I would like to emphasize that every design-element for each piece produced for me by Starfleet Astrosystems was the result of an open-ended brain-storming collaboration between Mr. Shevade and myself... and that no physical work was done prior to my final approval.


I believe the excellence of the results speaks for itself... and I encourage interested C-N members to contact Anurag Shevade via PM. I will also add that other than being a very satisfied customer, I have no financial interests or involvement whatsoever, in Mr. Shevade’s business ventures.


By way of "prelude to a follow-up"... it appears that a more typical summer-like weather pattern has finally arrived in this SoCal inland valley, so I am hopeful that at some point in the next month or so, I will be able to post some "photographic results" in this thread, as demonstration of the solidity of these two systems.


Stay tuned!  biggrin.png

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#5 cytan299


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Posted 29 June 2019 - 01:19 PM

Looks very solid! Can you post a link to starfleet astrosystems? My cursory search did not find the website.



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#6 B 26354

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Posted 29 June 2019 - 05:58 PM

He doesn't yet have a separate website. Just search for Anurag Shevade in the "Members" listing.  grin.gif

Edited by B 26354, 29 June 2019 - 06:01 PM.

#7 antariksha



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Posted 30 June 2019 - 08:35 AM

Just to add to the above very elaborative and well articulated post on "Guide scope on custome CnC machines...", I have an excellent experience of Anurag Shevade of Starfleet Astrosystems, too.

He has made a custom mounting arrangement for Orion 80A scope. I have been traditionally into observational work with my 18". I am getting fascinated by astro photography. My setup is Manfrotto tripod and ball head, EOS M3 camera, Orion 80A OTA and Fornax Equatorial drive system. The key challenge was the need for rings and a dovetail bar to mount Orion 80A. Further this needs to be mounted on ballhead. The last piece was really tricky. Anurag has done outstanding and precise job for this.

While I am still learning the photography and perfecting my technique, the above system is sturdy and well made.

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#8 CharlesW


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Posted 30 June 2019 - 10:17 AM

The one thing you have to be conscious of with a Vixen based SBS system is the teeter totter effect caused because everything is clamped to a single, fairly narrow, bar. If you spun your Stellarvue and camera upside down you could get rid of the riser blocks. That will reduce the twisting effect on the Vixen and help bring your counterweights in, reducing the moment arm. I would also spread the rings on the Stellarvue as far apart as possible to help stabilize the tube better.  

#9 B 26354

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Posted 30 June 2019 - 10:57 AM

The one thing you have to be conscious of with a Vixen based SBS system is the teeter totter effect....

Thanks very much, Charles. I've been a visual observer for 65 years, but only began looking into AP a couple of years ago... so the whole SBS thing is obviously a new approach for me, and any ideas from the more experienced of you out there, are truly welcome.


As you've no doubt realized, aside from eliminating the off-axis weighting effect of the finder-scope's stock mounting position on the ES refractor, the whole point of being able to completely eliminate it from the active AP setups was an attempt to reduce moment-arm... so I seriously appreciate your suggestion to spin the SV/camera combo! Makes perfect sense... as does spreading the SV's rings.


Thanks again!

#10 Terra Nova

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Posted 03 July 2019 - 06:30 AM

Wow! That is an impressive rig you’ve put together Terry!!

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