The Giant Binocular

[savarin]

Thanks Ray, slowly getting there.

 

[WobblyHand]

Quite remarkable, @savarin . I'm amazed at your perseverance and your ability to cobble together interesting machines to help you your way. Where did you get the inspiration/plans for the rough grinding machine?

My father had started to make a telescope, but he never finished it. I have a couple of pieces from him. He even made a Foucault tester. I have a single book on making a telescope. I've looked through it, but can't quite fathom all that is necessary. I know you have posted this before, but do you have a short list of sources that captures the overall process and most of the details?

 

[savarin]

The grinding machine was my idea but there are similar ones around that probably triggered the ideas.
The plans were back of the envelope stuff as I went along.
This is probably the best book available

How to Make a Telescope, 2nd Ed.

By Jean Texereau Product Information: 9.38" by 6.00", 440 pages, hardbound. The first edition of How to Make a Telescope was universally acclaimed as the best book ever written for making a Newtonian telescope. This 2nd Edition is almost three times larger and adds to the original text new...

shopatsky.com

and this one is also pretty good.

The Dobsonian Telescope

The Dobsonian Telescope, A Practical Manual for Building Large Aperture Telescopes tells how you can build a state-of-the-art Dobsonian telescope using readily available materials and supplies. Every step of construction is detailed in photographs and diagrams, and the underlying ideas are...

shopatsky.com

whats the book you already have
You can make excellent mirrors by hand, it just takes longer than the machine
(says someone who has been working on this for years)

 

[rwm]

This is great! What a process. You are a talented and patient man!
I look forward to the result and watching your Foucault testing!
And I seconds Rays comments bout this type of black magic.

 

[WobblyHand]

The grinding machine was my idea but there are similar ones around that probably triggered the ideas.
The plans were back of the envelope stuff as I went along.
This is probably the best book available

How to Make a Telescope, 2nd Ed.

By Jean Texereau Product Information: 9.38" by 6.00", 440 pages, hardbound. The first edition of How to Make a Telescope was universally acclaimed as the best book ever written for making a Newtonian telescope. This 2nd Edition is almost three times larger and adds to the original text new...

shopatsky.com

and this one is also pretty good.

The Dobsonian Telescope

The Dobsonian Telescope, A Practical Manual for Building Large Aperture Telescopes tells how you can build a state-of-the-art Dobsonian telescope using readily available materials and supplies. Every step of construction is detailed in photographs and diagrams, and the underlying ideas are...

shopatsky.com

whats the book you already have
You can make excellent mirrors by hand, it just takes longer than the machine
(says someone who has been working on this for years)

Thanks Savarin. I have "How to Make a Telescope" by Jean Texereau 1957. Seems to be a first edition. This edition has 197 pages. Seems like a lot got added to the second edition!

 

[savarin]

Grinding the steel tools is taking a lot longer than I expected.
The bottom tool is formed concave to grind the mirror backs, the top tool which will end up at the same curvature except convex to grind the aluminium puller disks.
Heres a video showing the grinding process with 80* grit, the top tool is free wheeling, it just overlaps the bottom disk/tool. This causes the tool to spin faster in the centre of the bottom tool and slower at the edge thus deepening the curve.
I have approximately 2/100ths mm to go in the centre.

(I hope)

Why am I building a giant binocular?
Because these are the largest I have (25x100) and I need-want-desire-hope for- greater magnification.

I built these so at public sessions I could find the object then lower or raise the height to fit anyone else looking through them.

 

[wachuko]

Any update on this build?

 

[savarin]

The steel tools took way longer to grind than I thought but they are there now so all going well tomorrow I will cut the ply disks and start grinding the backs of the mirrors.

 

[savarin]

2 hours work at 120 grit, the curve is showing

still a long way to go, I must purchase 1/2Kg more 80 and 120 grit.

 

[Firstram]

Once the backs are ground, will you grind a socket to receive the glass on the platen for alignment? How will you confirm they are concentric?