[ARC5] Arc-5 screw removal

[Brian Clarke]

In my experience, the most frequently broken-off screws are into the blind 
bushes supporting potted capacitors and wound components. Here, the pots and 
bushes are often plated brass - so, heating and cooling will have no 
differential effect whatever.

In such cases, advancing the sheared off screw further into the blind bush 
does you not a blind bit of good.

73 de Brian, VK2GCE.

Neil wondered on Monday, March 12, 2012 2:31 PM:

> The consensus seems to be that, other than using a dentist's pick
> to try to rotate the broken-off section out of the threads, the
> operation requires precision drilling and is beyond the ability of
> the average guy who has only a cordless drill.
>
> I had been thinking along the following lines:
>
> 1. drill a small pilot hole in the centre of the shaft
> 2. heat or cool (I'm not sure which) the entire item to take advantage
>    of the different coefficients of expansion of aluminium and brass
> 3. drill at very low speed into the pilot hole with a blunted bit whose
>    diameter is somewhat larger than the pilot hole and somewhat less
>    than the minimum thread diameter.
>
> The idea being that the blunted bit would bind when entering the
> pilot hole and slowly rotate the brass screw out.
> I don't have the workshop to carry out the procedure. Does it have
> any merit?
>
> 73 de Neil ZL1ANM