Yea maybe I went off on that when I should not have. “Fools rush in where wise men dare not tread”!

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I guess what I was trying to say in too many words was that even the best machines in a lot of cases cannot produce a perfect product and then one has to jump in and tweak things. It is all too common and I have been there many times. Some call it cheating and most call it just plain making it work. A lot of stuff you make that has to really be down there in the Microns has to be hand worked. That is what I was trying to say. Even back in the day when I worked on the stamping lines at Ford when I was 22 there were guys on the end of the line pounding, sanding, and tweaking the quarter panels as they came off the line. Most fenders and quarter panels were good but there was always the slugs and scratches, and inclusions in the metal ?that had to be removed manually. It is just the way of it.

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Well if I can find that article on how even the biggest mirrors have defects that have to be reworked in small spots I will post it. I might have seen it in one of my collection of movies.

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Three of my favorites are The Journey To Palomar, Observatories Stonehenge to Space Telescopes, and Seeing in the Dark. It might have been mentioned in one of the first two I don’t remember.

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If you or anyone else wants to watch a good movie about the Palomar telescope I highly recommend the first movie.

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Seeing in the Dark is recent of course and every time I feel like just giving up and taking up drooling and drinking I watch Seeing in The Dark. It motivates me. It was made by Timothy Faris a Berkley Professor. I contacted him and we talked. I asked him if he had any pictures of his observatory because I wanted to build one like it. He said “no but had some photos he sent me and I kind of reverse engineered his observatory and built mine.

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Seeing what other amateur astronomers went through is just mind boggling. George Ellery Hale’s life and his accomplishments will make you cry. His struggle to build the million pound Palomar 200 inch telescope in the 1930s and 43 was an epic battle and the man struggled with his sanity to boot. You want to talk about holding tolerances in that day. All I can say is my hat is off to him.

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The story of the mirror and Corning glass is one of the greatest documentaries I have seen, well at least on astronomy. I wish all could see it as it is a tribute to the man and his accomplishments. Even the War put the mirror in storage for 10 years but still the scope was built on a mountain that had no roads. It traveled by truck across the US and every town had hundreds of people lining the streets to watch “The Big Eye” as it was called go by with full police escort as it traveled across the length of the US. It was a great time to be alive and an American.

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Well sorry for going off on you I just get passionate sometimes. I have seen so many people say things about machining that have never done any and I just shake my head. I guess it just comes with the years I spent turning the handles as we say in the trade. I love machines? but they do have their limitations. Over at ASU where my best friend still works, and I do part time, they have a milling machine that has hollow lead screws in it through which flows coolant which goes through its own cooling system and keeps the lead screws to a constant temp in order that they do not change length and of course is able to maintain very accurate control of the tables and consequently the part tolerances as it produces parts. Still lapping and honing is standard practice in manufacturing when tolerances become so small that you almost cannot measure them except optically like when it comes to scopes and optics.

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I have worked on Automobile Dies so large that I had to climb into them and lay on my back to grind them into shape and have worked on parts so small like those in electron microscope cartridges that I can honestly I have worked on everything from the “ridiculous to the sublime”! ASU has over 20 electron microscopes and I have worked on a lot of them. They have one called the “Midas”, cost 1.5 million. I have taken many parts out of it and rebuilt them or made modifications to it like an Electron Energy Analyzer I built for one of the users. I did not design that but did build many modifications to that and other Electron Microscopes but that was another time.

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Take Care

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Gary

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Carpe Noctem

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Stan

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I was not going to get into this any further but want to say one last thing.

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I do not know if you have run any machine tools or for that matter built anything of a complex nature but this is something that a lot of people do not understand.

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Machines are fine and they do good jobs to a point. The more precise things have to be made more and more things come into play like temperature, wearing to the tools slop in the machines and of course competency of the operator. All this goes into the mix. Tools wear out and machines wear out. Cutting tools are abrading things and they wear out even diamond tools or ceramic cutting tools.

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Materials when cast like glass, steel, and on and on when cast have tremendous internal stresses. When you machine these materials, and I have machined almost every conceivable material known to man you release great internal stresses. I have known people that made parts and put them away for a month or two only to open the box to find them in hundreds of pieces because of the stresses. I know these things and why because I was trained as a tool and die maker by Ford Motor Company when I was in my twenties, I am now 70.

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I have worked all my life in the trades and spent the last 20 years working for the Physics & Astronomy Department at Arizona State University. While most people only read about things I have built some instruments and projects for the Center For Solid State Sciences that to list all would require another two or three pages but suffice it to know that I have work on Electron Microscopes, built Scanning Tunneling Microscopes, parts for three Thermal emission Spectrometers for three Mars missions a field enlarge to go onto one of the telescopes down in Tucson for Jeff Hestor the guy that took the picture of the Pillars of Creation and the list goes on and on. If you want references to my projects I will supply them. I currently work for Rogier Windhorst the guy that is working on the James Web Space Telescope.

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I don’t usually get into this but I do make exceptions.

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OK enough of that crap. I just want you to know that I have built stuff with my hands that most people can only dream about and still am. When I say something I speak with a little authority, not much, but with some. I worked for a company called Oberg Industries and worked on dies that stamped out the Lead Frames, that is the metal parts of integrated circuits and did all my grinding with diamond wheels some 100 grit and some DuPont 600 grit wheels which you could not remove more than a thousandth or more at one time. I have worked in gear factories when I was 20. I worked in a stamping plant for Ford and built many dies for them. I have worked for Monsanto and serviced their bottle blowing machines. I have worked for Johnson & Johnson and the list goes on and on and on.

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I know what it is to lean on a Parker Grinder when grinding a carbide insert for a die which must be ground to 50 millionths of an inch every day. Not maybe 50 millionths but closer than 50 millionths.

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So when I ask you does a wild bear poo in the woods or if a frogs butt is water tight you might just answer yes but when I say a rooster can pull a freight train you had better hook him up.

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I have lapped many things in with 3 micron diamond lap and too many other things to list. I have been in the trades for over 50 years so I have picked up a little on the way, not much but more than the average bear boo boo.

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Now I am done and you can say what you want.

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Gary

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Don

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Yes you can align by the method Dean suggests and I have him seen him do it in person. It requires a bit of skill as l have and said you have to stand back just the right distance and center the baffle tube in your field of view. The trick is to get just the right distance from the scope so the outer edge of the primary is just visible as you look directly into the scope it is a bit of a trick but it can be done. It is harder to explain then it is to do however.

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Good Luck and I hope Dean lived up to my praise. He is a great guy and a fair guy.

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Regards,

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Gary

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Carpe Noctem

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Don

At this point I will defer to Dean the owner of Starizona but will add these comments.

Please allow me to pontificate.

First in order to replace the washer you will have to remove the corrector. It can be done with added difficulty by not removing the corrector but you could scratch the corrector coatings which is not a good thing to say the least. This is a task that should not be taken lightly. On the Edge as well as on other SCT models the corrector is centered, actually moved into position, in the scope front tube end ring and this is not always the exact center of the front tube ring hence the need for shimming, screws, etc, and alignment.

In the real world there is also a little matter of a thing called “coplanarity”. Everything you manufacture has a certain flatness and each plain has a certain ?alignment with regards to other ?plains on other components of an assembly. This applies to lenses surfaces and the surfaces to which lenses are mated with. Now you throw in a big aluminum tube with holes in the periphery which are aligned with holes in the end housings of the scopes. You see where this is going. This is why mounting rings etc. have to be twisted and turned so as to allow for the most perfect coplanarity of all components. Now you throw in “axial” alignment and you begin to see the complexity of optical systems. Not even say the secondary mirror back surface which is flat may be perpendicular to the focal point axis of the curved mirror so collimation takes care of this also.

Not all scopes are created equal. Sometimes in the manufacturing process or components or in assembly all the errors cancel out each other and you have a perfect scope. On other occasions you have the “combination” of errors working against you, this is what is known as a “lemon” and you get a fair scope. Yes they are still within the acceptable design criteria but not as good as the “Perfect” scope. It is just a matter of luck sometimes. Sometimes we play these errors against one another in an assembly to our advantage and it is done a lot.

In manufacturing there is a thing called Geometric Tolerancing. It is a method by which all parts are made so as alignment with other parts in complex assemblies will be insured. It is different than simple part print tolerancing and is necessary in complex assemblies.

In a perfect world everything would be flat, round, concentric, perfect in axial alignment, etc. and the list goes on. Optical alignment is a pesky thing.

In the early days corrector alignment was accomplished with cork shims, which eventually shrunk, and of course this was done on an optical bench, as they still do. The alignment of the corrector can be done to a degree, and I use the term degree in a comparative nature, by eye. This however in no way, compared with the alignment accuracy needed for astrophotography, is acceptable. This applies many times over for Edge Scopes. With the edge you are paying for as nearly as possible perfect optics and superior alignment. This is what you paid for. There is a white paper on the Edge scopes and it can be found here and I suggest you read it as it is very good information for anyone. It mentions the set screws used for corrector alignment. Once again everything depends on the user or what you are willing to settle for.

I actually made components for three Thermal Emission Spectrometers for three Mars missions and some of the tolerances on mating surfaces were a PIA and all this was to insure the least amount of mechanical alignment in the final assembly. My parts are still circling he planet on the Mars Global Surveyor some setting on the planet on two subsequent mission’s instruments, and yes I have bragging rights that is why I am blowing this horn. LOL LOL It is all that an old guy like me can hope for these days. I am not an optical engineer by an stretch just an old Tool & Die maker but like an old ship I have picked up a few barnacles along the way. I have a “fair” degree of understanding of the esoteric, and the emphasis is on the word “fair” only because of my many years in the trade and I might add that sometimes I am wrong. “To err is human.” Actually the only time I was wrong when I said I was wrong but was not! LOL LOL LOL

By the way as mentioned in the article it says “The instruments designer” actually not true! It is the matter of the “s”. I was “a instrument designer” not that instruments designer. Sometimes reporters make errors. I am sure that burned the butts of many at JPL. LOL LOL Unfortunately worlds may come and go but the Internet lives on forever. LOL

I have done a few corrector removals and reinstallations on Celestron scopes but not Edge scopes as I was shown how to do this by Dean down in Tucson. I know just enough to be dangerous. LOL The alignment by eye and is subjective at best especially by the great unwashed. With Dean he can do a good job because he has done thousands. On a regular Celestron and for eye piece viewing this may be acceptable depending on whether or not you are a purist. By the way for full disclosure I have a 14” Edge Celestron Scope. I bought mine before they were released and had to wait 4 months for them to be delivered.

Now on the Edge. This alignment of the corrector is done by set screws located around the periphery. This insures no shrinkage because shims are not used and a more precise location method was needed. With screws also comes inherent risks as you are screwing screws against the edge of the corrector. Now to be honest if you remove just enough set screws to free the corrector and leave in three you could theoretically remove the corrector do your work and then reinstall it pushing it to one side against the screws that you did not disturb but one would never know for sure that you had attained the alignment you had before that was done on an optical bench. And of course it goes without saying that the corrector has to be put back ?in at the exact same rotational alignment as it was before it was removed.

So you see the magnitude of the problem, there are caveats in any endeavor.

Depending upon your level of skill and “boldness”, read “cojones”, as Robert Frost would say, “Two Roads Diverged in a Yellow Wood, and sorry I could not travel both. And be one traveler, long I stood”. The choice is yours “Should I stay or should I go”? ?

Choose wisely but talk to Dean he is the master short of the factory and will give you the best advice. If you are within driving distance perhaps a road trip is in order besides I always learn when I go there even just to chat. You never know who you might meet there as Tucson is a hot spot for many astronomers.

You will not meet a finer man than Dean at Starizona, his crew, and of course his charming wife Donna and you can take that to the Bank.

Sorry I pontificated but you were warned and I never fail to abuse a captive audience! All this because of a washer! Yikes! LOL

Read the White Paper it is an interesting read.

Gary

Carpe Noctem