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Elli Buk Cave 10" Cassegrain

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#1 turk123

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Posted 04 May 2013 - 08:28 AM

I thought I would start another thread now that the Buk is in my possession. I started by cleaning the tube. What a difference. It looks pretty solid with a little bit of spider cracking around some of the bolt holes. But I really wanted to get at the mirror.

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#2 turk123

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Posted 04 May 2013 - 08:31 AM

There were no markings on how the mirror was positioned in it's holder or in the tube. I removed it carefully to find a very dusty coating on on the top of the mirror.

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#3 turk123

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Posted 04 May 2013 - 08:33 AM

I took out the mirror and put the whole thing in the sink. I used my "special" formula telescope solution and distilled water and got the dust layer off. Bugger was really dirty. The mirror looks great.

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#4 turk123

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Posted 04 May 2013 - 08:39 AM

OK, now for the back of the mirror. It is NOT a Cave , just as we all anticipated. It looks like the word "chemoptics" is written in red on the back. The picture is in B & W and enhanced to see what is scribed on the back in pencil I believe.

R=80 7/8' and the words "Oblate no bad zones"

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#5 tim53

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Posted 04 May 2013 - 11:02 AM

those tube rings are really something. I've never seen such thick rings on a Cave.

-Tim.

#6 davidmcgo

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Posted 04 May 2013 - 11:25 AM

What is the central hole diameter? Protostar had a small diameter Blacklite tube already flocked that is approx 38mm outer diameter and was a good fit with some adhesive felt for my DK primary baffle.

Dave

#7 turk123

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Posted 04 May 2013 - 02:39 PM

What is the central hole diameter? Protostar had a small diameter Blacklite tube already flocked that is approx 38mm outer diameter and was a good fit with some adhesive felt for my DK primary baffle.

Dave


The hole measures 41mm. Sounds like what you got would work. I looked on their site but did not find anything with that small a diameter. I can call them on monday.

Thanks for the tip. I may use one of their liners for the inside of the large tube also. The existing flocking has turned light grey and is not in very good shape.

#8 Compressorguy

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Posted 05 May 2013 - 01:38 PM

Very nice score Turk and great job on the mirror. It looks great. Looking forward to seeing her back together and first light report. :waytogo:

#9 starman876

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Posted 05 May 2013 - 01:58 PM

Another great scope find. Great find

#10 turk123

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Posted 05 May 2013 - 02:36 PM

Thanks guys.

I just started taking the back mirror holder apart. It is definitely "hand" crafted as the drill hole only line up one way. I marked the parts with a steel punch ( . . ) two dots so I know how it all goes back together. Everything came apart very easily (so far) and now it is off to paint and polish.

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#11 turk123

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Posted 05 May 2013 - 02:39 PM

I measured and photographed the distances that it came set at just for reference when it goes back together. I also removed the 2" focuser. It still has the original "Sky Micro" band on the focuser knob shaft.

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#12 turk123

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Posted 05 May 2013 - 02:40 PM

The focuser also only fits one way, recessed into the back aluminum plate. It was machined with very tight tolerances.

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#13 turk123

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Posted 05 May 2013 - 02:42 PM

Here is the Sky Micro 2" focuser with my Teleview "beer can" eyepiece.

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#14 turk123

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Posted 05 May 2013 - 02:44 PM

Here are the "markings" I put on the parts. This is the first (and I'm sure not the last) time I used a hammer!

It's funny, but after doing this, I am finding double marks just like mine on several surfaces of the metal. Someone had my idea back then.

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#15 turk123

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Posted 05 May 2013 - 02:49 PM

Here are the locking screws and adjusters springs. These are not used to adjust the mirror, but only to lock down after the mirror is adjusted. There is a smaller threaded rod ( 3 ) with hex ends that are used to adjust the mirror. It is not shown here but is shown in front of the larger screw in the previous picture. It allows the mirror to be locked down after all adjustments are made.

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#16 terraclarke

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Posted 05 May 2013 - 02:52 PM

Hi Tom,

It's already looking great, just with a little cleaning. You are going to have one fantastic telescope there. With regard to the mirror: After cleaning, it looks great, as you say. I would attribute this, at least in part to the coatings. As I remember when I sent my 6 inch F4.5 mirror off to Cave for the final parabolic figure and for aluminizing, that in their literature they advertised special, corrosion-resistant coatings along with the aluminizing. If I remember right, they said that a fine layer of zirconium? was deposited over the aluminized surface to protect it. They said that the finish on the mirror, thus treated, should last many years with proper care. This was in the mid 1960s. Which brings me to my last point, I wonder if "Chemoptics" hand written on your mirror could have been the people who applied the aluminizing and coatings. My point being that maybe you do have a Cave mirror? Perhaps some of our other SoCal folks here that remember Cave back in the day may be able to shed more light on Chemoptics.

#17 turk123

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Posted 05 May 2013 - 02:53 PM

Here are all the parts assembled together. The screws at the top are mated with spacers. Below and center are the adjustment screws for the mirror and below that, the three lockdown screws.

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#18 turk123

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Posted 05 May 2013 - 02:56 PM

Next step is to give the stews, washers, spacers, springs and nuts a rust remover bath. Main parts have been washed and will get a light sanding and paint.

Also, everything has it's own bag and is marked. I don't want to go looking for each part later on.

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#19 turk123

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Posted 05 May 2013 - 03:11 PM

Hi Tom,

It's already looking great, just with a little cleaning. You are going to have one fantastic telescope there. With regard to the mirror: After cleaning, it looks great, as you say. I would attribute this, at least in part to the coatings. As I remember when I sent my 6 inch F4.5 mirror off to Cave for the final parabolic figure and for aluminizing, that in their literature they advertised special, corrosion-resistant coatings along with the aluminizing. If I remember right, they said that a fine layer of zirconium? was deposited over the aluminized surface to protect it. They said that the finish on the mirror, thus treated, should last many years with proper care. This was in the mid 1960s. Which brings me to my last point, I wonder if "Chemoptics" hand written on your mirror could have been the people who applied the aluminizing and coatings. My point being that maybe you do have a Cave mirror? Perhaps some of our other SoCal folks here that remember Cave back in the day may be able to shed more light on Chemoptics.


I took the mirror back out to the bench and cleaned the back a bit more. I used a very bright light to try to see if there are any other markings at all. I found nothing on the back and sides. It would be interesting to know the history of these mirrors. I agree, throw it out there and see if anyone can supply us with more history.

By the way "chemoptics" in korea was founded in the 90's I believe and may not be associated with this company name on the back. It also may be a company that moved to Korea.

#20 PiSigma

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Posted 05 May 2013 - 03:12 PM

Looking great so far Tom.

I've seen alignment marks on a number of Cave mirror cells. Here are the ones on my Model B Deluxe. These look cast in whereas the ones on my Custom Super Deluxe are hand punched.

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#21 Compressorguy

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Posted 05 May 2013 - 03:56 PM

Really!........."Astronomical" themed ziploc bags. Very professional. You cant teach that. :bow:

#22 turk123

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Posted 05 May 2013 - 05:01 PM

Really!........."Astronomical" themed ziploc bags. Very professional. You cant teach that. :bow:


OH, I hoped nobody saw that. :o

#23 turk123

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Posted 05 May 2013 - 06:43 PM

The telescope back was pretty pitted and oxidized (see earlier photos). I did some research on polishing aluminum on the internet and discovered a company called Zephyr. They have polishing compounds, polishing wheels, and a system to get a mirror finish out of aluminum. Here is what I bought.

The bars are the polishing compound. Different degrees of cutting and polishing. Brown is the highest grit then white and finally rouge red. The polishing wheels also have degrees of roughness and ability to polish. Finally the buffing wheel is used last to get the final finish.

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#24 turk123

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Posted 05 May 2013 - 06:47 PM

I set up a rig outside. The last polishing job I did brought the wrath of the lady of the house down on me for spraying the basement with compound. She was right, and I didn't clean it up. So I was banished to the outdoors. The tarp is their to protect me from further wrath from damaging any plants or brickwork.

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#25 turk123

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Posted 05 May 2013 - 06:50 PM

The back is a smooth aluminum. It is pitted and not really that even. I figured it could get a good clean and polish to make it look a little better. I won't bore you with the entire routine, but i gradually went through all the degrees of polish and polishing wheels and did a final buffing.

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