Well, for those interested: Please note that I am in learning mode. I am sure I have done some inappropriate things along the way but perhaps the advice of those with greater experience can point toward further enlightenment.
First, the B&L was found, as stated above , in a thrift store. Down in the basement. It came with a blow-molded case, the table-top tripod legs, an instruction booklet, the scope itself, and that's about it. No diagonal, and no eyepieces. Naturally I had those at home anyway. It did include the visual back (I believe that is the term) which adapts the back of the scope to the standard 1.25 inch diagonals and eyepieces. I have learned that the B&L has a weird thread size for this adapter. And it also came with a regular tripod with the aluminum plate for mounting the scope base to the tripod.
At home, after calming down from the junk find, I went out on the patio and started looking over the scope. I set it up on a table and tried viewing the trees down the street with a 40mm eyepiece. The view was absolute crapola, with lots of aberrations around the edges of the leaves, but it did confirm that the focuser worked. Looking at the collector plate, there was a not-so-thin film of gunk which indicated that some previous owner stored the scope on the counter next to his cook stove where he deep fried pork fritters while smoking cigarettes. No choice but to dismount the collector and clean.
I don't have the proper tool for unscrewing the collector retaining ring, but used a set of snap ring pliers and a small vice grip plier to achieve the proper pin spacing. With the collector out, I noted that the secondary mirror also had some bits of fluff on it. (Calm down, I know what some of you are thinking)
Ok, my first error probably was removing the secondary mirror. I was very careful and it was easy to remove (just a central screw) but I made no attempt to record the position of the secondary. Anyway with the small mirror out, I carefully flooded the surface with isopropyl alcohol and then followed with distilled water. Didn't have any deionized water. Followed by a gentle compressed air flow over the mirror surface and all the fuzzy bits were gone.
The collector was cleaned in similar manner, but the film was not going to budge with flooding alone. I purchased a very soft make up brush and with isopropyl flood gently massaged the surface. I then rinsed with EtOH, followed by distilled water and the gentle (filtered) compressed air. Now the collector looked good, at least to my eyes. I had done some light reading on cleaning mirrors, but mostly I was improvising. Corrections as to techniques and materials would be appreciated.
Another newbie mistake probably was that I did not index the position of the collector. I have read that some scopes are tuned by turning the collector. I'm pretty sure that this scope was so badly out of fettle that the axial position of the collector may not make any difference, but any ideas on that front would be appreciated as well.
No attempt was made to remove or clean the primary mirror.
After reassembling the scope tube, I discovered that the aluminum plate to which the scope mount is connected (the plate that carries the AC motor for star tracking) was bent. This poor scope did indeed lead a tough life. Upon dismounting this plate, it was found that in addition to being bent, it was also fractured around the central axle of the plate. Well, nothing ventured......I used a carbide bur in a dental lab handpiece to grind about 4mm on either side of the fractures, and then subjected the plate to Al soldering.
Parenthetically, I have found that Al solder works pretty well for most Al hobby repairs. Definitely not TIG welding strong, but not really too bad either. And no melting of the parent metal. It takes a bit of practice, but works somewhat like "regular" low temp soldering. If anyone is interested I could come up with a link for the technique.
After soldering, I mounted the plate in my South Bend lathe and spent a casual ten minutes bending the plate back into an approximation of flat. None of the solder joints fractured, so I felt pretty good about that.
Well, with the secondary mirror no where near a correct position, I though I would just wait for night and use a star to roughly approach collimation. Pretty humorous, as I attempted to find the little set screws with a 1.5mm hex wrench. In the dark. I searched around for another idea and found, probably here on Astromart, the substitute star, Christmas ornament in the sunshine method to get things started. I was too wimpy to go up into the attic to find an ornament (mid 90's F here right now) so I found a chrome hitch ball in the tool box and zip tied it to the stop sign pole about 200 feet down the street. The neighbors don't even shake their heads at my crazy schemes any more. Nice neighbors.
Anyway, after fiddling around for a pleasant half hour, I have nice round doughnuts on either side of focus, and now the leaves on the trees look nice and sharp. I know, this will never be a Questar or even close, but so far it has been an enlightening project. Once Autumn happens here in the US Midwest, the skies will clear enough to try the scope out on some astronomical viewing.
I got a bit long winded but hope my adventures are entertaining and/or helpful, and perhaps provide some discussion points.
Clear skies,
David B
