[ARC5] [Milsurplus] Penetrating oil test - Youtube

[Michael Hanz]

That's an excellent question, Wayne.  For years, I've followed these 
kinds of tests closely for obvious reasons, and a lot of them are 
subjective, with little in the way of scientifically designed boundary 
conditions.  I have them back to over ten years ago, and probably 
further, mostly in the vehicle maintenance and home shop machining 
communities for obvious reasons.  Everyone swears by this solution or 
that, but the sample set that any one of us radio guys personally has is 
painfully low - how many of us do it on a regular basis with dozens of 
samples?  And the real problem is that the size of the test threads in 
these tests is almost always significantly larger than the relatively 
small screws (like knob setscrews) that we have to address most 
frequently.  Life ain't always linear.

There is a later method that I've found useful, but it too involves some 
limitations based on surrounding knobs/handles/etc., and that's an 
induction heater.  The most difficult setscrews I have ever encountered 
are on the glued-in screws in BC-191/375 transmitter dials, and 10-15 
seconds of heating works wonders without harming the black bakelite 
knobs or paint at all.  If you can fit the coil around the knob, it has 
always provided the cure - at least for me. This has been verified by 
the home shop machinist and vehicle communities as well, but the 
difficulty is always the geometry of the frozen screw/bolt with respect 
to surrounding structures.  The professional models are a bit pricey and 
require a bevy of different coil shapes and sizes in an attempt to cover 
the most situations.  I picked up one for a few bucks on Amazon (search 
"low voltage induction heaters", if interested)  but the quality of 
these Chinese products runs all over the place, and you do need to wind 
more than one coil set for different size radio knobs.  The good news is 
that these cheap drivers generally work on 12-14vdc or 24-28vdc, 
voltages which may sound familiar to most of you.


As a result of its limitations, I would never call this solution the 
answer to the "Ultimate Question of Life, the Universe, and 
Everything".  That allegedly remains "42" according to _The 
__Hitchhikers Guide to the Galaxy_.  YMMV.  😁

Just another data point for consideration...as if we needed more.

      73,
  - Mike  KC4TOS

On 4/24/2023 12:26 AM, hwhall at compuserve.com wrote:
> What should we make of a chart that shows some products sometimes make 
> the required torque higher than if we used nothing at all??
>
> Wayne
> WB4OGM
>
> -----Original Message-----
> From: Hubert Miller <Kargo_cult at msn.com>
> To: milsurplus at mailman.qth.net <milsurplus at mailman.qth.net>; 
> nwvrs at googlegroups. com <nwvrs at googlegroups.com>
> Sent: Sun, Apr 23, 2023 9:19 pm
>
> I have been puzzling, and kind of dreading, how best to approach 
> frozen setscrews in an old
> radio. As if that isn't enough of a challenge, the frozen setscrews ( 
> grub screws ) are in positions
> difficult to reach with any tool. What fun that will be. So this 
> little video was of some interest.
> -Hue Miller
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