Jump to content


Photo

DIY Antique Telescope Reproduction

  • Please log in to reply
236 replies to this topic

#1 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 10:51 AM

The purpose of starting this thread is to share with you folks a project we started this summer, and will be working on for the next couple of years. The project is a 3/4 scale reproduction of the Alvin Clark 8 inch refractor at the Seagraves Observatory in Rhodes Island. The telescope was made 1878. I say “we” because this project is a team effort with myself and Allen Hall. Although a team effort, we are each making one of these telescopes. We will be combining our talents and experience in engineering, optics, and metal working. We have just started, and in these first few posts I will share progress up to now. As progress is made, I plan to update the thread. By doing this, I hope you will enjoy seeing the project unfold, and benefit from reading and seeing some of challenges we had to overcome.

I want to say, right up front, this is intended to be a “beautiful” telescope. I have plenty of telescopes to look at the sky with. I can make any telescope I want, to look at the sky with. This is an art project and a historical research project, and I hope it is appreciated as such. This telescope will be completely DIY. That is optics, machining, and finishing.

The first photo is a picture of the actual Alvin Clark telescope that we intend to reproduce in reduced scale. It has been restored by the Skyscrapers. The Skyscrapers is the astronomy club in Rhodes Island that has this beautiful, quality, relic of past glory under its care. The effort of the Skyscrapers to restore this telescope was under the leadership and technical direction of Allen Hall. You may read more about this restoration by visiting the Skyscrapers website. Click on library and scroll down. Or go directly to www.theskyscrapers.org/content5296.html

Dick Parker

Attached Files



#2 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 10:53 AM

This next photo is a closeup of the mount. This is the part where we begin our construction. It is the foundation upon which to build. The style of this mount design is referred to as a harp mount, due to the rather obvious harp like shape of the large cast iron frame.

This telescope was made by Alvin Clark & Son’s for Frank Seagrave. Mr Seagrave was wealthy and this telescope is adorned with lots of beautiful brass and bronze parts. Mr. Seagrave had this telescope made for his son who devoted many years using it to plot the accurate position of stars. As a result, the setting circles were very precise and finely graduated.

The motion of the telescope was accomplished by a falling weight and chain system, similar to clocks of the time. The motion was regulated to sidereal rate by a flyweight governor. That governor is not in this photograph, and will be discussed later.

Dick Parker

Attached Files



#3 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 10:55 AM

This next photo shows the full size flyweight governor that Allen and I made for the original telescope. The original governor was destroyed by vandals and lost in the 1960’s and not available to restore nor examine. Allen did an amazing job of reverse engineering the governor from old fuzzy photos taken of the telescope while the original drive was installed. This photo was taken while this drive was on display at Stellafane 2007.

Dick Parker

Attached Files



#4 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 10:57 AM

And the governor installed on the telescope. It now works and tracks better than the electric system that was incorporated in the 1960’s.

Dick Parker

Attached Files



#5 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 10:58 AM

OK. Now that you have seen what it is that we are reproducing, let’s get started. The attached picture is my frame. The original was cast iron and hollow. For our reproductions, we chose to make this part out of aluminum. We considered a casting, but that did not make economic sense. We made the frame from three pieces of aluminum. The harp was two halves of one and a half inch aluminum plate stock, and the base was made from two inch thick plate stock. The two halves of the harp were bolted together then cut out on a bandsaw. The bolts holding the two halves of the harp are on the other side, but the cavities will be filled and the whole thing painted semi gloss black at the appropriate time.

Dick Parker

Attached Files



#6 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:00 AM

Allen started by digitizing coordinates from a profile photograph on Solidworks. From that we developed precise drawings of the harp profile. A portion of that profile drawing is shown here.

Dick Parker

Attached Files



#7 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:01 AM

Shown in the attached photo is the step of hollowing out the harp. This step is optional, but I chose to do it. By hollowing out all the parts I reduced the total weight from 47 lbs to 25 lbs. I do not have CNC capability, so this was done manually on my Bridgeport. It reminded me of drawing with an etch-a-sketch as a kid.

Dick Parker

Attached Files



#8 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:02 AM

This picture shows the base on the Bridgeport, upside down, hollowing out from the bottom. Ribs were left in for strength.

Dick Parker

Attached Files



#9 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:03 AM

This picture shows the base, top side up, with the pocket for the harp.

Dick Parker

Attached Files



#10 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:04 AM

This picture shows a closeup of the harp inserted into the pocket in the base. The challenge was to machine the pocket sufficiently precise that the harp fit in easily, yet the joint would be invisible.

Dick Parker

Attached Files



#11 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:06 AM

This picture shows both Allen and my frame on display at this years Astroassembly, hosted by the Skyscrapers.

Dick Parker

Attached Files



#12 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:08 AM

This picture shows Allens frame with the polar shaft machined and the thrust bolt and bracket installed. The polar shaft is tapered and the front and rear bushings are also tapered on the ID to fit precisely the contour of the shaft. (shaft bushings not yet installed in this photo). The Clarks were clever. To adjust the friction of the shaft in the bushings, the thrust bolt pushes the shaft up the taper. This way, the position of the shaft can be precisely adjusted so that there is just room for the oil film that lubricates the shaft bushings. You can imagine that since the shaft and bushings are tapered, the exact ID and taper are important and must be precisely matched to the distance between the bushings. The bushings are not shown yet in this progress photo.

Dick Parker

Attached Files



#13 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:10 AM

Close up of thrust bolt and brass bracket. The addition of the brass parts really starts to add the beauty to this assembly.

Dick Parker

Attached Files



#14 Dick Parker

Dick Parker

    Viking 1

  • *****
  • Posts: 765
  • Joined: 17 Aug 2007
  • Loc: Tolland, CT and Chiefland, FL

Posted 05 December 2009 - 11:11 AM

This is a photo of the objective that will be used. This objective is shown installed in my telescope in an aluminum cell. The glass will be removed and installed in a bronze cell made for this reproduction. The objective is a 6 inch f/15 Baker airspaced objective using BK7 crown and F4 flint. I have made two of these objectives for my use. One of them will be used for this project. Allen has started grinding his objective elements. Both of these objectives use glass originating from Newport glass kits.

That’s all for now. I hope you enjoy this project. Please feel free to comment.

Dick Parker

Attached Files



#15 RossSackett

RossSackett

    Surveyor 1

  • *****
  • Posts: 1718
  • Joined: 17 Aug 2007
  • Loc: Memphis, TN

Posted 05 December 2009 - 11:37 AM

That is going to be fantastic! I look forward to watching the project progress.

Ross

#16 jayscheuerle

jayscheuerle

    Aurora

  • *****
  • Posts: 4675
  • Joined: 16 Jan 2006
  • Loc: S. Philadelphia, PA

Posted 05 December 2009 - 11:50 AM

This thread will NOT be able to have too many pictures. :) - j

#17 Gary Fuchs

Gary Fuchs

    Apollo

  • *****
  • Posts: 1365
  • Joined: 22 May 2006
  • Loc: Easton, PA, USA

Posted 05 December 2009 - 12:09 PM

Dick and Allen,

Another stunning project -- after your matching 16" Cassegrains and mounts we saw at Stellafane in 2008. Wow.

I'm especially interested to know more of the engineering and construction details.

Gary

#18 polaraligned

polaraligned

    Viking 1

  • -----
  • Posts: 691
  • Joined: 26 Dec 2008

Posted 05 December 2009 - 12:15 PM

I want to say, right up front, this is intended to be a “beautiful” telescope. I have plenty of telescopes to look at the sky with. I can make any telescope I want, to look at the sky with. This is an art project and a historical research project, and I hope it is appreciated as such. This telescope will be completely DIY. That is optics, machining, and finishing.


If it ends up anything like yours and Allens other projects, it will be a sight to behold. :jump: I anticipate seeing the pictures as you progress. :jump:

I have always admired the harp style mount and even considered it for my 6" f/15. There has been a small harp with a 5" or 6" Clark refractor on it at Stellafane in the past. Unfortunately, I don't think it is as stable as a modern GEM (pound for pound), so I ruled it out. But boy, they sure look good!!

You will have a beautiful scope to hand down for generations to come.
Best of luck.

#19 Happy-Idiot

Happy-Idiot

    Stuck with it

  • *****
  • Posts: 4154
  • Joined: 06 Apr 2006
  • Loc: 3rd Rock

Posted 05 December 2009 - 04:09 PM

Wow! I am glued to this thread. :waytogo:

#20 Wes James

Wes James

    Fly Me to the Moon

  • *****
  • Posts: 5504
  • Joined: 12 Apr 2006

Posted 05 December 2009 - 05:13 PM

Dick/Allen- I am stunned at this project. I am a huge fan of fine machine work, and antiques... Your project- a combination of the two- you can be certain I will be anxiously following your progress. Absolutely beautiful.

#21 plyscope

plyscope

    Apollo

  • -----
  • Posts: 1484
  • Joined: 23 Nov 2006
  • Loc: Perth, West Australia

Posted 05 December 2009 - 06:08 PM

Very impressive work Dick, thank you for sharing this.

#22 John Carruthers

John Carruthers

    Skiprat

  • *****
  • Posts: 3551
  • Joined: 02 Feb 2007
  • Loc: Kent, UK

Posted 06 December 2009 - 03:47 AM

:bow: :bow: :bow:

#23 Bill Cheng

Bill Cheng

    Vostok 1

  • -----
  • Posts: 185
  • Joined: 21 May 2005

Posted 07 December 2009 - 11:19 AM

Wow, Amazing work. Dick you be the man. Love to see you bring that to Stellafane and bring the house down.

#24 Jim Curry

Jim Curry

    Surveyor 1

  • *****
  • Posts: 1700
  • Joined: 29 Oct 2007
  • Loc: STL

Posted 07 December 2009 - 08:46 PM

This is going to be a wonderful project to monitor. I'm really looking forward to it!

Jim

#25 Scott Milligan

Scott Milligan

    Vostok 1

  • *****
  • Posts: 116
  • Joined: 08 Sep 2005
  • Loc: MA

Posted 10 December 2009 - 07:49 PM

Dick:

Oboy, this one is gonna be special! I have often fantasized about having all prerequisites (mostly talent & time) in place to do something like you and Allen are embarked on now. Obviously, the force is with you, and Yoda is proud. :p






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics