Giant binocular

[34_40]

quite the collection of linkage.  What are the functions?  I'm assuming some sort of zoom perhaps?

[savarin]

A brief description of what has to happen with astronomical telescopes.
The parabolic mirror reflects the light travelling down the scope back up to a secondary flat mirror that reflects that light out the side usually into an eyepiece where it is focussed.
All the mirrors have adjusters, the primary mirror has three adjusting screws that tilt the mirror to make the light cone hit the secondary at the right spot to be reflected out into the eyepiece.
These adjusters are usually at the bottom of the scope underneath the mirror cell.
Once adjusted correctly they usually only need a tiny tweak now and again.
This is called collimating the mirror.
In a binocular each tube then has to be adjusted to bring both the images into call it co-collimation so your eyes can successfully merge the two images into one.
 If this co-collimation is a bit out your brain takes over and merges them for you BUT in the process giving you the most thunderous headache ever.
All these rods will allow me to tweak the co-collimation whilst looking through the eyepieces to ensure the images do allign perfectly. (I hope)
The first one as pictured is actually to move the complete mirror cell sideways as another aid in merging the images.
One mirror will move at 90' to the other mirror.
I hope this makes some sort of sense.

[34_40]

makes a lot of sense now! never knew there was so many things going on in there. And I can imagine the headache.. every couple years I get new eyeglasses so I've experienced that pain.  Thanks for the info.

[savarin]

I have been doing bit, honest, but life has the habit of getting in the way.
Both mirror cells are finished, the mirrors will sit of the ring of soft rubber, a rubber disk will be glued to the back of the mirror with an aluminium disk glued to that. 
The mirror backs will be ground to a convex radius of curvature of 142.5", the aluminium disks ground to a concave roc of 142.5" as well, the middle of the ally disk has a 10mm bolt pulling the mirror down onto the rubber border distorting it from a spherical roc to a parabolic shape.
The front concave curve of the mirrors need a radius of curvature (roc) of 144", this will be ground in roughly with the abomination of a machine shown below.
 The pendulum carries a spinning diamond disk at its end.
I used a diamond cutting disk with WD40 to hollow out the aluminium disks but was very surprised at how long it took.
 (And the mess)
 To set it up I set the pendulum at 122.5" from the centre of the top pivot to the edge of the diamond blade.
 I then adjust the three tripod legs so the diamond disk "just" kisses the edge of the aluminium disk all around.
 Then raise the legs equally till the diamond disk touches about an inch from the centre and start grinding, the aluminium disk rotates anti clockwise pretty fast and the diamond dish rotates clockwise so it cuts against the direction of the main turntable. Lower the pendulum a little and off again, rinse and repeat.
 The arrow is to remind me, if I get the direction wrong the diamond disk rides up onto the aluminium disk too fast to control. No big deal but if it happens on the glass mirrors they have a habit of cracking. (dont ask me how I know)
The large disk with all the steel dumps epoxied to it is the main tool to grind the mirror backs at 142.5" roc. This has to be kiss ground at 122.5" roc to just clean it up.
Another tool has to be cast in this to use on the aluminium disks to get them tidied up to 142.5" roc. 
The two glass disks were ground out at 144" roc with the diamond disk blade and plenty of water to keep the glass dust down.
They ground down about an hour each but one of the disks chipped on the edge. I'm hoping a good chamfer will solve the problem but if not I have enough glass to cut another one.

[34_40]

UM..... WOW! 

[Jake Parker]

I like that grinder pendulum set up bud!

[savarin]

Thanks but I wish I had thought of using a cheap angle grinder on the end instead of the slow spin dryer motor, it would have been easier and lighter to swing. Also the faster speed of the angle grinder would have produced a smoother surface.. Still, it did get the job done.