The Giant Binocular

[Boswell]

Wow, that is a lot of glass removed in two hours. Do you have to worry about glass dust in the air? I assume it is a wet sanding but when the water evaporates do you have to take special precautions with the waste?

 

[savarin]

Kitchen paper soaks up the waste which I then bury so it joins the rest of the sand in our soil.
The mirrors will be sat face down on a flat surface, a rubber ring will fit around them also flat to the surface, an expanding cake ring will clamp onto the rubber, then plaster fills up the remainder.
When set its set the rubber and cake ring are removed then its set on the turntable face down, the back of the plaster is skimmed flat and parrallel to the face, flipped and the front surface is ground and polished. phew!
The rubber ring allows the mirror to sit proud of the plaster backing.

 

[savarin]

Heres the back side of the mirror ground to 400 grit with an even curve and no zones to the best of my measuring ability.
its very smooth but I stopped at 400 so there is a bit of a key left for the glue to bond.

Heres the jig with the 400 diamond lapidary disk smoothing the edge and getting the mirror rounder.
Its sprung loaded so keep grinding till the diamond disk stops pulsating in and out.

The glass is held in place under tension from that central bolt pressing downwards.
I will have to make a 45' bracket to hold the diamond disk at that angle to cut the edge chamfer.
If you look close at the join between the steel disk and the glass you will notice a large chip out. This happened when the vertical pendulum grinder ran away from me a hit the edge. I'm hoping I will be able to remove most of it when I chamfer the edge, if not and it screws up the figure I have a heap of 19mm glass to cut another from.
Still so much to do.

 

[wachuko]

...
If you look close at the join between the steel disk and the glass you will notice a large chip out. This happened when the vertical pendulum grinder ran away from me a hit the edge. I'm hoping I will be able to remove most of it when I chamfer the edge, if not and it screws up the figure I have a heap of 19mm glass to cut another from.
Still so much to do.

Oh man! That sucks . I do hope you can remove it with the chamfer...

 

[Downunder Bob]

Well done Charles your continued persistence with project far exceeds anything I could cope with. Keep up the excellent work

 

[savarin]

Thanks Bob, I dont know if its persistence or stupidity.
Another spoke in the works this arvo.
I could smell something not right and checked the motor that drives the stroke, it was way too hot to touch so when it cooled I dismantled it thinking maybe a blown bearing as I couldnt turn it.
One magnet loose and one magnet broken into 3 pieces no wonder it couldnt turn.
Now the wait for a new one.

 

[Boswell]

Now the wait for a new one.

on the positive side, this will give you more time to collect puns.

 

[savarin]

Ok.
Have you ever used a telescope
If not, you should look into it

 

[WobblyHand]

Ok.
Have you ever used a telescope
If not, you should look into it

Groan. Thumbs up on that one.

Can you epoxy the magnets back together again in the interim? Or is the motor running too hot for that adhesive?

 

[savarin]

I'm going to try that but the broken one cant be joined back as the poles appear to oppose each other so I will just use the larger piece and see what happens.
Getting all 4 brushes back in wont be easy either.