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Equipment Discussions >> Classic Telescopes

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dgreyson
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
Re: Elli Buk Cave 10" Cassegrain [Re: Datapanic]
      #5930315 - 06/19/13 11:18 PM

Dan, the trouble I had using the guidescope on the rotating rings is that my Guidescope is just too short to bridge across both rings. I'd use my Not-a-unitron-128 scope instead but I'd rather have it on my after market Equatorial mount for observing. Plus, I really need the weight up front to get my shorter Cave scope to balance.

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Chuck HardsModerator
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Re: Elli Buk Cave 10" Cassegrain [Re: dgreyson]
      #5930345 - 06/19/13 11:34 PM

My guidescope rings are just like Tom's as well. Being a patternmaker, I could easily duplicate them for sand casting, and even build in the correct shrinkage factor for aluminum. 3/16" per foot, if I recall correctly.

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Chuck HardsModerator
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Re: Elli Buk Cave 10" Cassegrain [Re: Chuck Hards]
      #5930383 - 06/20/13 12:03 AM

Thinking about it, it would be easier to reproduce them in fiberglass. They would look identical, and weigh less. Aluminum cores could be laminated inside the rings at the adjusting screw locations, to hold the threads, but probably wouldn't be necessary.

Hmmm...


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dgreyson
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
Re: Elli Buk Cave 10" Cassegrain [Re: Chuck Hards]
      #5930392 - 06/20/13 12:12 AM

The heavy rings like tom's would be much easier to cast and should perform better as they ought to be rock solid compared to the elegant style thin rings.

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Chuck HardsModerator
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Re: Elli Buk Cave 10" Cassegrain [Re: dgreyson]
      #5930428 - 06/20/13 12:35 AM

Quote:

The heavy rings like tom's would be much easier to cast and should perform better as they ought to be rock solid compared to the elegant style thin rings.




True. Looking at my set, there is ample draft, and considering their size, there will be negligible shrinkage. Probably only 1/16" overall, at most.


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Datapanic
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Re: Elli Buk Cave 10" Cassegrain [Re: Chuck Hards]
      #5930443 - 06/20/13 12:46 AM

Quote:

Quote:

The heavy rings like tom's would be much easier to cast and should perform better as they ought to be rock solid compared to the elegant style thin rings.




True. Looking at my set, there is ample draft, and considering their size, there will be negligible shrinkage. Probably only 1/16" overall, at most.




1/16" would be close enough. Most of the stuff Cave made was at that tolerance anyways!

(not that I'm bad mouthing Cave Stuff, but a lot of it was eyeballed anyway)


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tim53
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Reged: 12/17/04

Loc: Highland Park, CA
Re: Elli Buk Cave 10" Cassegrain [Re: Datapanic]
      #5930943 - 06/20/13 09:49 AM

This would be a cool discussion for a thread of its own!

I have a propane forge I bought from a blacksmith's friend's widow several years ago (along with his decked-out Craftsman 618 lathe and 6" f/5 Jaegers). I bought it because my son was interested in blacksmithing. He used it about a year before changing interests. I've used it a couple times with him. You can just about melt iron with it, so aluminum and brass would be easy. There isn't a lot of room, though. Probably a foot square and only 4 inches high, opened at one end. Would need a short stocky crucible.

-Tim.


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turk123
Carpal Tunnel
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Reged: 07/09/10

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Re: Elli Buk Cave 10" Cassegrain [Re: tim53]
      #5933979 - 06/22/13 12:29 AM Attachment (13 downloads)

Started on some larger parts using the etching primer. Goes on nice in my paint booth.

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turk123
Carpal Tunnel
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Reged: 07/09/10

Loc: N.E. Ohio
Re: Elli Buk Cave 10" Cassegrain [Re: turk123]
      #5933980 - 06/22/13 12:29 AM Attachment (10 downloads)

One more

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turk123
Carpal Tunnel
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Reged: 07/09/10

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Re: Elli Buk Cave 10" Cassegrain [Re: turk123]
      #5933981 - 06/22/13 12:30 AM Attachment (12 downloads)

Setup area

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Chuck HardsModerator
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Re: Elli Buk Cave 10" Cassegrain [Re: turk123]
      #5933984 - 06/22/13 12:35 AM

You're taking a step Tom Cave didn't bother to, but doing it right. As I sand-down one of my Astrola mounts prior to a repaint, it's obvious that there isn't a drop of primer on any of it. The color was sprayed directly on the metal, and is probably the reason much of it has just flaked-off over the years.

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Datapanic
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Re: Elli Buk Cave 10" Cassegrain [Re: Chuck Hards]
      #5933998 - 06/22/13 12:51 AM Attachment (15 downloads)

Quote:

You're taking a step Tom Cave didn't bother to, but doing it right. As I sand-down one of my Astrola mounts prior to a repaint, it's obvious that there isn't a drop of primer on any of it. The color was sprayed directly on the metal, and is probably the reason much of it has just flaked-off over the years.




One other thing that Cave didn't do, which would have been a lot of work, was to grind down the flange of the cast aluminum parts, like shown here in the Maynard Clark legs. It really helps the appearance, but he probably felt it unnecessary for production.


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dgreyson
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Reged: 11/06/12

Loc: South Carolina
Re: Elli Buk Cave 10" Cassegrain [Re: Datapanic]
      #5934012 - 06/22/13 01:06 AM

I think on Chrome you have to have a very smooth finish or it shows every defect thru the plating dont you? Primer and paint when done right with sanding between coats fills in and smooths over imperfections that would stick out like a sore thumb in Chrome.

Mr. Cave, like any other company with a bottom line, just needed the paint to hold up till the warranty ran out. Im sure he never dreamed anyone would still be clucking over them like so many hens in a different millenium from his.


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Datapanic
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Re: Elli Buk Cave 10" Cassegrain [Re: dgreyson]
      #5934043 - 06/22/13 02:05 AM

That's not chrome - it's aluminum.

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tim53
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Re: Elli Buk Cave 10" Cassegrain [Re: Datapanic]
      #5934474 - 06/22/13 11:44 AM

You should see the castings on my observatory mount up close. Huge file and angle grinder marks!

I'm going to leave it original, though I'll probably strip the paint and prime it properly someday.

Tim


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dgreyson
scholastic sledgehammer
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Reged: 11/06/12

Loc: South Carolina
Re: Elli Buk Cave 10" Cassegrain [Re: Datapanic]
      #5934597 - 06/22/13 01:05 PM

Quote:

That's not chrome - it's aluminum.




Really? wow! Well in that case it's ready to be Chromed then.

I will keep my setting circles and trim polished and waxed but I'm not sufficiently motivated for keeping every rung in the feet much less everything else shiny. no.

They invented Chrome because there weren't enough Butlers and Chauffeurs to go around for everyone who needed something polished.


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Chuck HardsModerator
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Re: Elli Buk Cave 10" Cassegrain [Re: dgreyson]
      #5934670 - 06/22/13 02:01 PM

I believe the only chrome plated part is the steel pier, everthing else is polished, cast aluminum.

Someone has posted that early models did have aluminum piers, but apparently not the bulk of the company's production.

I've seen some Astrolas with highly polished counterweights instead of the black wrinkle finish. I assume those are also plated steel or iron. And the shafts themselves are of course unplated steel.

Having some good pneumatic grinding and polishing tools will allow me to remove the lines formed on the legs between the cope and the drag sections of the mold, without it turning into a month-long project. I really like the clean looks. Low on my list, though, since I'm starting with the OTA and working down. The legs are last on the list.


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gelkin
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Reged: 09/22/10

Loc: Western, MD.
Re: Elli Buk Cave 10" Cassegrain [Re: Chuck Hards]
      #5934877 - 06/22/13 04:01 PM Attachment (9 downloads)

Quote:

Having some good pneumatic grinding and polishing tools will allow me to remove the lines formed on the legs between the cope and the drag sections of the mold, without it turning into a month-long project. I really like the clean looks. Low on my list, though, since I'm starting with the OTA and working down. The legs are last on the list.



I would agree, and spent hours filing / sanding on my light weight castings


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turk123
Carpal Tunnel
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Re: Elli Buk Cave 10" Cassegrain [Re: gelkin]
      #5934929 - 06/22/13 04:27 PM

Very Very nice, Gerald.

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Chuck HardsModerator
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Re: Elli Buk Cave 10" Cassegrain [Re: gelkin]
      #5935510 - 06/22/13 10:49 PM

Quote:

Quote:

Having some good pneumatic grinding and polishing tools will allow me to remove the lines formed on the legs between the cope and the drag sections of the mold, without it turning into a month-long project. I really like the clean looks. Low on my list, though, since I'm starting with the OTA and working down. The legs are last on the list.



I would agree, and spent hours filing / sanding on my light weight castings




The power tools are nice, but you have to do plenty by hand anyway; small corners and hard-to-reach places that only deterimination and elbow grease can master. You did a beautiful job!

If there is a heaven for telescope makers, I'm sure Tom Cave is smiling down on you.


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