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Interested in Ottawa-based mirror coating for telescope optics?
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Hi Everyone,
I've been toying with the idea of coating my own telescope mirrors. By coating, I mean vacuum physical vapor deposition with aluminum and some kind of SiOx overcoat. I might be able to acquire an old commercial-grade coating system, with an ~18" or so diameter chamber. It's been sitting unused for at least a decade, maybe more. If I had the thing up and running, would anyone be interested in having their mirrors recoated locally (I live downtown Ottawa)? I've never done this before, so it's definitely going to be amateur quality (at least initially). Thanks, -Adam |
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Being able to drive to a coater always beats having to ship a mirror. But i, for i one, happen to not need any mirrors coated at the moment. On Fri, Aug 27, 2021, 14:13 Adam Bell <adambell714@...> wrote: Hi Everyone, |
开云体育I don’t have any mirrors at all. ?Might there be a new customer promotion: ?“Free mirror with every recoating”?
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开云体育I grind occasional mirrors and I know at least one other grinder who might be interested.? But we'd want to see some good results before sacrificing a mirror!? ;)? Not many people grind their own any more and I don't know how often people get their mirrors recoated.? Alan Ward at Moonward Coatings in Sudbury was doing them for many years with some intermittent gaps due to various reasons.? I'm not sure if he is still doing them but there is a website giving 'current' prices. Rick ---------- Original Message ----------
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I did not know about Moonward Coatings. I recently had a small mirror recoated by Normand Fullum. It seems like he did a good job and he has a good reputation from what I could gather.
I have a few mirrors to practice with. I wouldn't dare risk someone's fabricated mirror unless I was confident it would not be damaged. I'm also planning on grinding some mirrors, eventually. I'm doing this little project with a friend from work and "coating" beat out "grinding" as the more interesting of the two. I was thinking of a very basic vacuum system to start, using a few "junk" vacuum pumps from work. But then I spotted this full-fledged coating system in storage. It's probably close to 1000 lbs and will be a considerable effort to install in my basement (assuming I get the blessing to give it a new home). Not to mention the many hours needed to get it back into working condition. For the few mirrors I might produce myself, it's a little excessive. But if several other people are interested, it helps make the case for the effort. This could be a lot of fun! |
开云体育Again, Moonward may not be in operation any more.? I notice their website is copyright 2003. Normand Fullum does have a good reputation and he does lots of other very cool things.. OK, tentatively you can put me down for a couple of coatings. Rick ---------- Original Message ----------
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开云体育Well, I'm not doing much right at the moment.? Some time ago I finished a 6" f/4 (as yet uncoated) that I plan to use for a guidescope (prime focus - no secondary) for the Boltwood 16".? And I have a hankering for an 8" or 10" ultra short f/3 or f/3.5.? Also trying to work up a satisfactory design for a 10" f/5 corrected Dall-Kirkham. Rick ---------- Original Message ----------
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开云体育I've got a 12" that needs recoating - once there have been some successful jobs done. Not sure I'm up for being a guinea pig. Bill On 8/27/2021 2:13 PM, Adam Bell wrote:
Hi Everyone, |
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A really interesting idea. My first thought was that a) I didn't even really know people?had mirrors recoated and b) I would probably never need that with something like an SCT. Maybe a Dob. And then on the Cdn Astronomy marketplace on FB, there was a posting this week for someone selling his 16" truss Dob and lo and behold, what does he say? The mirrors might need recoating. Which made me think, "Hey, there might be someone in Ottawa who can do that at some point." Paul |
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My theoretical understanding is that the coating lifetime is influenced by environment (chemical action) and handling (mechanical action). So if your mirror is in a well-sealed enclosure and you never touch it for cleaning, I'm guessing that it won't need re-coating for decades. If you own a dob and you observe often (i.e. lot's of environmental exposure), then you will eventually want to re-coat the mirrors.
My experience with a couple small reflectors that were poorly stored for many many years is that the coatings lose their reflectivity generally and develop uneven defects. I had a 4.5 inch mirror re-coated by Normand Fullum and it made a noticeable difference at the eyepiece. That coating was in pretty bad shape, initially. It would be fun to experiment with a few weathered mirrors and try and establish a 'before' and 'after' reflectivity. Something quantifiable would be best. For the moment, I've been given the blessing to use the equipment until further notice. It was ear-marked for Carleton University, but it's been sitting in a warehouse for years. I'll try and restore it over the next few months as a side project. First step is "coat some kind of glass with aluminum so it looks shiny". It's good to hear that there are at least a few locals who need things aluminized. -Adam |
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