The Giant Binocular

[savarin]

Good excuse to make or buy a wobble broach setup.

Allen keys are case hardened, If they were hard all the way thru they would snap off all the time. That is why you can twist without breaking them in a very stuck fastener. Once you start grinding the case is gone.

Ah ha, I didnt know that. I have some drill rod on the way to make one, I dont like that word "buy"

 

[Flyinfool]

There are a few threads here on HM for building a wobble broach.

 

[Firstram]

, I dont like that word "buy"

That’s too bad, I was hoping to buy you a beer someday!

 

[savarin]

I'm sure I can make a special exception

 

[Downunder Bob]

Hi Bob, its not the screws I need to be hard, they will have very little pressure on them.
They are .5mm pitch for the tension adjustment on the mirror backs.
I just had the idea of broaching a hex hole in the stainless to make my own.

Sorry Charles, I had the cart before the horse. However the same statement works for keys, A quality brand like "Unbrako" do have keys that are quite hard and tough. I have in fact done the very process you are trying to do, and it worked. Ok it was not into SS but worked in MS, I'd be checking the hardness of the SS. Good luck. I know you'll find a way, you always do.

 

[savarin]

At long last both plates are finished. I dont think I will ever try to do this again.

Next drill and tap and countersink M10x0.5mm.
Before I can start polishing the mirrors I have to totally clean the machine. There is carborundum dust everywhere, it has to be spotless to ensure I dont scratch a mirror.

 

[rwm]

Beautiful.

 

[7milesup]

Well, that was quick.

 

[savarin]

At last I am ready to polish the mirrors. First job is make the lap.
I used plaster that took over a week to thoroughly dry then soaked it in tile grout sealant to prevent it from adsorbing water from the polishing.
Used some firm plastic sheet to make a dam around the tool and poured a hot mix of pine resin and caster oil in.

Just before it was poured I tested the consistency with a 30 second thumbnail press to see it it raised a small lip, it did so it should be soft enough to conform to the mirror (He hopes)


remove the dam wall

bevel the edge

cut the facets

randomly score the lap and brush with a stainless wire brush to remove all particles.


coat the mirror in a very thick cerium oxide and water polishing compound layer

Lay the lap on top with a little weight and leave to cold press and hopefully conform to the mirror

Panic stations arise when you cant separate the mirror and lap.
I will find out tomorrow.

 

[wachuko]

Best of luck!!!