[ARC5] Removing knobs

[Glenn Little WB4UIV]

Most likely a Bristol.
If it has been damaged bad enough by attempting removal with the wrong 
tools, drilling is probably the only option.
I had to remove a knob from an ARC-5 control head by drilling because 
previous owner did not use proper tools and attempted drilling.
If you have to resort to drilling, use a new bit with oil.
Try a left twist drill bit first, you may get lucky and get a good bite 
on the set screw and back it out.
Start with a bit size that will just fit in the Bristol recess.
When you have drilled to the shaft, go to the next size drill.
Remember the oil.
The next size drill should complete the job.
If you have taken your time, what you will have left of the setscrew 
will look like a spring when you remove it from the knob.

73
Good Luck

Glenn
WB4UIV



On 11/16/2019 11:08 PM, Waldo Magnuson via ARC5 wrote:
> As a good friend frequency says, ???Before you do something, you always have to do something else first.???
>    Well, the audio volume switch on a C-1254A control unit I???m matching to a R-13B (108-135 mc) receiver no longer switches.  I have a new pot with switch to replace the bad switch but first have to remove the front panel knob. Allen wrenches don???t fit, it doesn???t seem to be a Phillips, a small screwdriver turns with resistance but nothing happens. I could resort to a demill (sp) and major surgery or try drilling out the knob holding screw but is probably hardened .
>    And suggestions would be appreciated.
> Skip Magnuson W7WGM
>
> PS:  Glad you came out ok Dave. Low voltages can get you too. I was changing the battery in my tractor and my crescent wrench hit my ring. I got the ring off right away but even after two years can see/feel the scar.
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-- 
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"