[ARC5] Removing knobs - verse two.

[Michael Hanz]

These are rarely easy to remove after so many years of being untouched.  
The other problem is the short distance from the screw to the control 
panel, which limits what you can get in there to help.

The single most effective way I have found to break it loose is to 
emulate an impact wrench.  Sometimes you can use the L shaped Bristol 
wrench for this, hitting it with a small hammer while holding it with 
needle nose pliers.  If that doesn't work, by removing the plastic 
handle of the DS series Bristol screwdriver below, you can adapt it to 
an extension bar and use it with one of the _small_ impact driver 
tools.  (Yeah, I know, it pains me to modify a good tool like that, but 
if you get desperate enough...)   You also have to cut the spline down 
to a very short section to minimize the torsional twist of the spline 
during the jolt (a long spline absorbs the torque like a torsion bar), 
but 9 times out of ten it will get the screw out with one blow.  Use a 
_small_ hammer, not a 5 pound sledge.  I think sometimes they used a 
drop of lacquer on the screw as a locking mechanism back in the day.




If all else fails, the screws _can_ be drilled with an appropriately 
sized _carbide_ drill.  They are sometimes hardened but a cabide bit 
will do it easily.  You still have to make some sort of adapter to 
connect the drill to the rotating mechanism...conventional chucks are 
usually too big and require tilting of the drill to the point where it's 
not very helpful in getting to the contact point on the shaft.

           73,
  - Mike  KC4TOS

On 11/17/2019 2:08 PM, Waldo Magnuson via ARC5 wrote:
> The set screw in the audio volume switch on a C-1254A control unit IS a Bristol set screw. The wrench fits tightly, I’ve used Blaster penetrating Oil but even with excessive torque the screw has not come loose. Any suggestions- heat/cold/drill?
> Skip W7WGM

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