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# McElroy Bug Key Project
Like I don't have enough projects of my own, sometimes I inherit
the projects of others.
This was the case with my ![1936 McElroy telegraphy key][1]. It
was gifted to me by its former keeper who, I think, wanted to see
it revived and thought I had the interest and skills to do it.
Not wanting to look a gift horse in the mouth, I didn't really look
at what I'd been given until I got home later that day.
It's old, well used and it's been mostly stripped down to its
![component parts][2].
After a general inspection most of it seems to be there but, some
of it is in desperate need of replacement parts or repair.
[1]: https://morsemad.com/mc_files/mc063.jpg
[2]: gopher://gopher.icu/I/images/McElroy/P1010341-sml.JPG
## Things needing attention
The spring steel which joins the control linkage to the pendulum
has ![broken][3] and the broken part has been lost so, I don't know
it's original length. There is however still part of the steel
riveted inside one of the parts that I can check with a micrometer
for thickness, once I've removed the rivets...
The rivets appear to be aluminium and so should only require some
careful drilling of the rolled edge before I can drift them out.
The rubber feet have turned to a stone like consistency. Unfortunately
whoever removed them sheared one of the screws almost flush in the
![cast iron base][4]. This will probably be the most difficult thing
to rectify without doing any damage.
Suitably sized replacement feet are already on order. They are not
an exact match for the originals but will be close enough for me.
The various pivot points appear to be very worn and in some cases
the wall of hollowed screws have broken away. I'm not quite sure
yet how I will fix these, possibly by simply grinding down the
height; if there is sufficient material to allow it.
[3]: gopher://gopher.icu/I/images/McElroy/P1010340-sml.JPG
[4]: gopher://gopher.icu/I/images/McElroy/P1010342-sml.JPG
### Update 28/07/2026
Today I set to removing the rivets from the pendulum assembly.
I held the components with some fibre jaw covers in the vice, to
save the vice teeth marking them. Then I selected a drill which was
just a little bigger than the hollow inside the back of the rivet
and carefully ![drilled][5] a couple of mm in with a Dremel.
Once I was happy that I was close to the outer edge of the rivet, I
selected a punch that would go just inside the drilled hole and
proceeded to give it a few light blows with a small hammer to see
if they would budge.
Looking at the underside I could see they were moving so, I proceeded
to drift them out. I did the same for ![both parts][6].
*Note:* Initially I had thought the rivets were aluminium, due to
their dull silver colour. However, upon starting to drill them, it
became obvious that they were in fact coated brass.
[5]: gopher://gopher.icu/I/images/McElroy/P1010350-sml.JPG
[6]: gopher://gopher.icu/I/images/McElroy/P1010351-sml.JPG
### Update 05/08/2026
The ![new feet][7] arrived and steadily I have day by day been
cleaning up components until all are clean and, where possible,
reassembled into their ![sub assemblies][8].
Plan A for removing the stuck piece of thread from the base failed.
There is not enough protruding to grab hold of it with some mole
grips. Plan B entails welding a new head (nut) onto the remains of
the protruding thread. For this I need my welder to be functioning
100% as I figure, I have just one shot at it.
My MIG welder has had a wire feed / jamming issue since I had it
and I never bothered to get to the bottom of it because it was good
enough. Unfortunately now, good enough is no-longer good enough as
I need to get a good weld straight off the bat.
Heat is usually a good way to remove stuck studs and nuts, but you
still need something to grip onto. My hope is that the heat from the
weld will do enough to loosen the stud and the welded on nut will
give me the purchase I need to unscrew it.
If I fail then, I will have to resort to drilling out the thread and
attempting to re-tap the hole. From bitter experience, this is not
a road I wish to travel...
[7]: gopher://gopher.icu/I/images/McElroy/P1010357-sml.JPG
[8]: gopher://gopher.icu/I/images/McElroy/P1010362-sml.JPG
### Update 08/08/2026
Plan B was a success at the second attempt.
I gave it my best shot:
* Soaked the thread for several days with good quality penetrating
oil.
* Struck the head of the thread a few times with a light hammer to
try to jar it.
* Shielded the base around the screw with a piece of copper by
drilling a 5/32 hole in it, which was precisely the size of the
thread.
* Tried to get a good deep weld through the nut and down onto the
head of the thread below.
The first time I tried welding through the nut directly but, the
weld wasn't deep enough and it fairly easily broke off. I needed
to get the stud hot so at the second attempt, I put a hot tack of
weld directly onto the head of the thread. Then I placed a fresh
nut over it and proceeded to weld through the nut with plenty of
power.
I put a small adjustable spanner on the nut and slowly started to
turn. This is the worst part as you don't know if your weld is
shearing or if the thread is actually starting to turn... After a
couple of rotations it was clear that I had it moving and I could
relax.
The ![extraction device][9] looks ugly, but it worked like a charm.
[9]: gopher://gopher.icu/I/images/McElroy/P1010364-sml.JPG
## Reassembly
Now that the stuck thread issue is out of the way and the base has
been cleaned. I have started the process of ![reassembly][10] and
ordered some of the replacement fixings.
This should leave me with just the pendulum assembly issues:
* Dah pivot bar being excessively worn.
* Replacement 0.017" spring steel strip.
* Replacement truss head, nickel plated 1/16 brass rivets x4.
* Rivet clincher, to close the above.
* Drilling the centres of the replacement grub screws.
[10]: gopher://gopher.icu/I/images/McElroy/P1010366-sml.JPG
### Update 11/08/2026
With my attention now fully on the pendulum mechanism, I started
to make enquiries to identify the length of the broken spring
steel.
I contacted a fellow amateur radio operator who was listed in the
above pdf document as having a McElroy key of the same model. He
very kindly took the pendulum from his own key and took several
measurements for me along with some high resolution photographs.
The dimensions he provided confirmed my height (3/8") and thickness
(0.016" - 0.017") measurements and also gave me the missing
![length][11] measurement (12mm between parts / 29mm total) which
I did not have.
After reading a few articles on how best to cut spring steel, which
has a high carbon content and is quite hard, there was a listing
of items commonly made from spring steel. This listing included
bulldog clips...
My brain started it's analytical process "I have bulldog clips, I
wonder what their thickness is?". So, I went hunting the house for
bulldog clips with micrometer in hand. The first one I found was
0.015" just a hair too thin, but promising. The second one was just
a hair thicker at 0.016", that was good enough for me.
Armed with the information that cutting was probably best done with
a cutting wheel on a dremel or hand grinder. I got the dremel, a
small vice and a face shield from the garage.
Fifteen minutes later I had a piece of ![spring steel][12] which
was over size but, right for the job once filed to the correct
dimensions. An hour later, after gently whittling away at the
dimensions with a file, I was ![within 0.5mm][13].
[11]: gopher://gopher.icu/I/images/McElroy/P1010376-sml.JPG
[12]: gopher://gopher.icu/I/images/McElroy/pendulum-assy-sml.jpg
[13]: gopher://gopher.icu/I/images/McElroy/P1010381-sml.JPG
### Update 14/08/2026
Often, taking the time to think something through before getting
the tools out is wise.
After trying in vain to dress what was left of the pivot that
actuates the 'dah', it basically crumbled away when I touched it
with a file, I knew I would need to replace the pivot bar.
I took a day or so to think about it and determined it was probably
pressed in, so it would be best to press it out. Rather than take to
it with a hammer and punch, possibly causing damage to the brass
by attempting to hold it.
The plan came to me. I had a piece of square aluminum in the garage
that has been used as a drift, it's about 30mm square by 120mm long.
I would drill a hole fractionally wider, and deeper, than the bar
I was trying to remove into the aluminum and use this as the base
of the press. The aluminum, being less hard than the brass, should
avoid any marking but offer enough support to push against to remove
the steel pivot bar.
There was about 3mm of bar protruding on the top side so I used a
4" bench vice and opened it up to take the aluminum and the component
and began to tighten the jaws of the vice to act as a press against
the protruding pointy head of the pivot bar.
As I started to bare down on it, I felt it ease. It had begun to
move, so I continued on until the vice jaw was within about 1mm of
the brass surface.
I didn't want to get any closer than that so I backed off the vice,
took the aluminum block placed it on the floor with the hole
facing up with the component sat on the top. At that, I went looking
for a suitably sized punch and a small hammer.
A couple of light blows with a small hammer was all it took to drive
it the rest of the way ![out][14].
Having put a micrometer on there it appears to be 1/8" steel bar
which should be reasonably easy to source. Not sure how I might
put the knurled ridges in it though...
[14]: gopher://gopher.icu/I/images/McElroy/P1010394-sml.JPG
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