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Re: Sextants and Glue [was Sisteco Prismatic Compass]
From: Fred Hebard
Date: 2004 Mar 21, 17:38 -0500
From: Fred Hebard
Date: 2004 Mar 21, 17:38 -0500
I used cyanoacrylic glue (Super Glue) to refit the filters. Acetone cleaned off my slight excess of cyanoacrylic quite rapidly. I didn't find any Un -Cure at the shops I went to, but I wouldn't be surprised if it's not acetone, or a similar intermediately polar solvent. It looks like there aren't any antireflective coatings on the filters, which I wouldn't expect due to the harsh service (exposure to salt water) expected of a sextant. I also repaired the broken clamp in the case, which was what led to the filters being in such sad shape. However, before the sextant is fit for sea, I would need to replace the clamp. I believe I'll follow Jared Sherman's suggestion on this and contact Robert E. White & Co. in Boston, MA for the clamp. They also sell reconditioned sextants; I wonder whether they still calibrate sextants. The Cassens & Plath is doing at least as well as my Husun; a few star shots the other evening came in at less than 0.35' of my actual location, and I still have not gotten really fine weather for observations, so I have hopes that it is not irretrievably foobarred. Then to buy a 6x30 scope! Fred On Mar 20, 2004, at 12:17 PM, Fred Hebard wrote: > Thanks Joel > > On Mar 20, 2004, at 11:53 AM, Joel Jacobs wrote: > >> Hi Fred, >> >> I suggest you get some Cyanoacrylate clue. It come is various >> viscosities. >> The one I like is blue labeled Super Thin with a cure rate of 1-3 sec. >> >> Experiment with this on some test items until you feel comfortable >> with its >> running action. >> >> A companion product is Un -Cure, a debonder. >> >> The glue is space age technology, and will work with anything. >> >> Best Source: Your local hobby shop. >> >> I also have some spare parts that might work though they are >> Japanese, not >> C-P. >> >> Joel Jacobs >> >> ----- Original Message ----- >> From: "Fred Hebard">> To: >> Sent: Saturday, March 20, 2004 8:56 AM >> Subject: Re: Sextants and Glue [was Sisteco Prismatic Compass] >> >> >>> Jared, >>> >>> I believe my sextant is the C&P Professional Sextant, as referred to >>> on >>> their website. However, I am not familiar with older designs. >>> >>> It has 3 horizon and 4 index filters plus an astigmatizer added to >>> the >>> the index filter rack. There is no added button on the micrometer >>> dial >>> for adjusting for dip and index error. The mirror housings are >>> aluminum, as best as I can tell. >>> >>> Most lens systems I have disassembled glued the compound lenses >>> together, but mounted them with threaded rings in the barrel. >>> Retaining clips also could be used for filters. >>> >>> If it's so easy to replace, do you know how I might dissolve the old >>> glue clinging to the two horizon filters that have fallen out and >>> what >>> sort of glue I should use to replace them? >>> >>> Fred >>> >>> >>> >>> On Mar 19, 2004, at 8:02 PM, Jared Sherman wrote: >>> >>>> Fred, I would bear in mind that most of the finest camera lenses in >>>> the >>>> world today are in fact built up from multiple elements--glued >>>> together. >>>> Glue is literally the stuff that makes precision optics possible >>>> today. >>>> >>>> If the alignment and material selection is done properly, the glue >>>> joint is >>>> stronger, lighter, and thinner than screwed metal rings. It will >>>> never >>>> seize >>>> up, and it is easily replaced when and if need be. >>>> >>>> There are also combat aircraft whose wings are literally glued on. >>>> Glue is >>>> not necessarily a bad thing! And if it happens to keep down the cost >>>> of the >>>> sextant, even better. >>>> >>>> Which sextant did you get? How big is the filter rack on it? (How >>>> many >>>> filters?) >>>> >> >