Re: Extracting a buggered knob grubscrew


I have not seen Torx screws on the older Tek equipment, so I looked it up.
Torx screws were apparently invented in 1967 but not patented until 1971. I
found this for history buffs:

By the way, one way I have removed stuck grub screws (aka set screws) is to
use an appropriate diameter left-handed twist drill bit (of course operated
in the drill or by hand in a counter-clockwise direction). I had a Tek
plug-in I was salvaging parts from. One of those shaft couplers with two
small Allen grub screws was absolutely stuck. The other came out easily. A
left-handed drill bit that grabbed the Allen recess (rather than just spin
in it) got it right out. Since the bit was smaller in diameter than the
threaded hole, there was no damage to the existing threads. The only thing
I noticed was that the head of the stuck grub screw was rusted - the other
was not. The threads in the coupler were also fine - no oxidation there.

Steve Horii

On Mon, Feb 1, 2021 at 3:28 PM Joseph Orgnero <> wrote:

In my experience Tek uses only Torx screws on their equipment, trying to
Allen or Bristol wrenches is asking for trouble.
Jose Orgnero VE7LBI

-----Original Message-----
From: Jeff Kruth via
Sent: Monday, February 01, 2021 11:56 AM
Subject: Re: [TekScopes] Extracting a buggered knob grubscrew

While I am sure there are many tips that others have, I found a thin hot
soldering iron pressed into the iron screw socket head will sometimes add
enough heat(expansion) to get things going. I have also filed cheap
screwdrivers into an appropriate sized chisel point and, using friction
tapped them into the end of the reamed out set screw with a small hammer.
This can then be grasped with a small pair of vice grips and the screw may
give.YMMVJeff Kruth In a message dated 2/1/2021 2:46:57 PM Eastern
Time, writes:
They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive but
someone forced a hex key in there it's probably not a Bristol drive

Unfortunately I have found no way to extract a stuck set screw of that
You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27 so
get a bit more grip. I don't know, seems random.

Jose Orgnero

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