[chbot] Repairing a 2.25mm shaft

[Helmut Walle]

In a time now long past I worked at an optometrist's briefly, and we had 
some really nice small-size brazing kit there to repair broken 
spectacles frames. That kind of tooling makes jobs of this size a 
breeze. Not sure, though, whether optometrists these days (throw-away 
culture...) are still doing this kind of work. But this could easily be 
found out by ringing one or two. My next best guess, if you can't do the 
work yourself, would be watchmakers or dental labs.

Just some ideas if for some reason you can't do it yourself.

Oh, and step changes in the diameter of shafts are not a good idea 
regarding long life - a smooth transition without sharp edges is far 
less prone to suffer from fatigue failure. But you already knew that, 
and then you didn't design the thing in the first place...

Kind regards,

Helmut.

On 25/02/2014 3:46 p.m., Robin Gilks wrote:
> Greetings all
>
> Its time I repaired my 'scope that had a knob snapped off during the Sept
> quake. Its a 2.25mm diameter brass shaft, about 120mm long with the
> knurled end for the knob to push onto integrated on the end of it which is
> 6mm diameter. The break is flush with the change in diameter.
>
> Silver solder may hold it, brazing certainly would but both have the risk
> of melting the parts I have, hence the solution outlined below which
> avoids trying to make a whole new piece which may not be viable.
>
> Drill into the shaft, maybe 10mm deep, with a .7 or .8mm drill, same with
> the remains of the knurled end, and put a short piece of piano wire in (as
> a dowel or splint) and then soft solder it up.
>
> Question is, does anyone in the group have the gear and/or skills to do this?
>
> Cheers
>