Re: Twiddlesticks

On Thu, 19 Jun 2025 19:15:28 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Thu, 19 Jun 2025 14:00:31 +0100, Cursitor Doom <cd@notformail.com>
wrote:
>

On Wed, 18 Jun 2025 18:03:03 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
>

On Wed, 18 Jun 2025 18:04:29 +0100, Cursitor Doom <cd@notformail.com>
wrote:
>

Gentlemen,
>
Many of us are familiar with the all-too-common problem of reciever
re-alignment. Dealing the vintage radios with fragile ferite cores in
their IF stages is unavoidable and can prove to be a major PITA. The
cores are brittle and eager to shatter at anything much above mm/mg
torque levels. The key is to use a tool which is not only non-metallic
but also a perfect fit for the slot it must engage with in the top of
the core. Given the range of sizes one encounters in this concern,
it's often necessary to 'roll your own' tool. Well I have a suggestion
to make. Wood makes the best tool for this job and opinions vary as to
which particular wood is ideally suited to this task. Lemon and orange
are often cited. But they're expensive and hard to source typically.
However, I've found a marvellous alternative: yellow heart. I don't
know what the technical name is for this wood, but that's what it's
informally called. It's cheaper and more readily obtainable than
orange or lemon and AFAIC, *better* than either with it's incredibly
fine grain and viceral hardness. It files and sands readily and when
dipped in cellulose sealer, will not fray in use.
Just thought I'd share that with you guys.
>
CD.

>
I have no experience with lemon or orange wood.  However, if they're
anything like the wooden tuning tools I made and used half a century
ago, I suspect you will have problems.  Wood absorbs moisture from the
air.  I had problems with the tuning changing at VHF (> 100 MHz)

>
It does absorb moisture if left untreated, yes. That's why it's
important to dip the finished tool in cellulose sanding sealer, wipe
it off, let it dry, then repeat the process.

>

The grain (which is
already very fine and tight with yellow heart) will now be impervious
to atmospheric moisture AND that grain will be bonded by the sealer,
making it much less likely to fray and thereby extending the useful
life of the tool considerably.

>
I beg to differ somewhat.  Trees and plants are designed by nature to
efficiently transport water along the trunk (or branches) through the
xylem using capillary action.  It can't do that while leaking water
through the outer layers (bark, cambium and phloem).  Those are fairly
well sealed.  The water transport doesn't stop when the tree is cut
down.  Think of the tree trunk as a bundle of soda straws.  The water
still moves along the length of the trunk.  Therefore, if you want to
prevent the tree from absorbing water, you need to protect the ends
and not so much the outside of the trunk.  Capillary action is only a
small part of the water transport system.  Most of the pressure comes
from the roots via osmosis.  For very tall trees, there's also
transpiration (pressure from evaporating water).  However, if all
you're worried about is water getting into your wooden tuning tool,
the small amount of water in the xylem will be noticeable at VHF
frequencies.
>
<https://www.reddit.com/r/boatbuilding/comments/hhaujy/why_does_planking_end_just_behind_the_bow/>
"This affirms the wooden boat builders trick of sealing the plank ends
with glue, even the staunch traditionalist will put glue on the end of
the planks."
>

frequencies.  This is about half of the tuning tools I've accumulated
over the years:
<https://photos.app.goo.gl/7Gq4r85pipeccUMz9>
>
My favorite do it myself tuning tools are ceramic rods.  Buy some
ceramic rods and grind the tips until they look like a "blade", Allen
wrench, or whatever.
<https://www.ortechceramics.com/products/ceramic-tubes-rods/ceramic-rod/>
>
My 2nd favorite is plastic.  I forgot which plastic worked the best. A
crude  test for a proper plastic is to put a sample in a microwave
oven for maybe 15 seconds.  I just tried it on some of the tuning
tools in my collection.  No heating, melting or fire.  Or, you could
just find a plastic that works as a coil form.
>
If you have a grid dip meter, measure the self resonant frequency of
an inductor and capacitor in parallel.  Find the resonance frequency.
Shove the plastic sample into the core (or nearby).  It should NOT
change the resonant frequency.

>
Certainly won't ifyou use wood either.

>
Huh?  I suggest you use some kind of ceramic or plastic, unless you
enjoy research projects.

Oh come along now, Jeffrey. These sticks will be totally fine for my
intented use at VHF.
Whereas in years gone by we used to argue the toss over who was right
and who was wrong in any given disagreement (which would invariably
result in a very lengthy thread in which neither party would admit
defeat) we can now - thankfully - defer to AI to arbitrate.
Consequently, I asked Grok with its planet-sized brain to look into
it:

*****************************************

"Thanks for dropping the exact quote from the internet guy. Let’s
dissect this claim about wooden tuning sticks and water in the xylem
causing issues at VHF frequencies. I’ll keep it tight and focused,
addressing his points directly while tying it back to your tuning
sticks made from Paulownia with cellulose sanding sealer.
The Guy’s Claim
The internet guy’s argument is that wood’s natural
structure—specifically the xylem, which transports water in living
trees—makes it prone to holding moisture even after being cut. He
suggests this residual water in the xylem could affect wooden tuning
tools at VHF (Very High Frequency, typically 30–300 MHz) due to
water’s dielectric properties. He describes trees as “bundles of soda
straws” (xylem vessels) that continue to move water via capillary
action, implying that wooden tuning sticks might retain enough
moisture to mess with a tuned circuit’s frequency when inserted into a
coil’s former.
Breaking It Down
Let’s analyze his points in the context of your tuning sticks and
tuned circuits:

    Wood’s Water Transport in Living Trees:
        He’s correct that living trees use xylem to transport water
via capillary action, osmosis (root pressure), and transpiration
(evaporation-driven pull). The outer layers (bark, cambium, phloem)
are relatively water-resistant, while xylem acts like “soda straws”
for water movement.
        Relevance to Tuning Sticks: This is true for living trees, but
once a tree is cut, processed, and dried into lumber (like your
Paulownia), the water transport system is no longer active. The drying
process (kiln or air-drying) removes most free water from the xylem,
leaving only bound water (chemically bonded to cell walls) and minimal
residual moisture. Properly dried wood, especially sealed wood, isn’t
actively moving water like a living tree.
    Capillary Action and Moisture Retention:
        He claims water still moves along the xylem in cut wood and
that protecting the ends of the wood (not just the sides) is key to
preventing moisture absorption.
        Reality Check: In dried wood, capillary action is minimal
because there’s no active water transport system (no root pressure or
transpiration). The xylem vessels are mostly empty air channels in
seasoned lumber. Your Paulownia tuning sticks, coated with cellulose
sanding sealer, are further protected against moisture ingress—both on
the sides and ends, since the sealer forms a barrier. The guy’s
concern about water movement in cut wood is overstated for properly
processed and sealed wood.
    Water’s Impact at VHF Frequencies:
        He argues that the “small amount of water in the xylem will be
noticeable at VHF frequencies.” Water has a high dielectric constant
(~80), so if present in significant amounts, it could increase the
capacitance of a tuned circuit when a wet wooden stick is inserted
into a coil’s former, potentially shifting the resonant frequency.
        Does This Hold Up?: At VHF (30–300 MHz), circuits are more
sensitive to dielectric changes than at lower frequencies (e.g., AM/FM
bands). However, the amount of water in properly dried and sealed wood
is tiny. For context:
            Dry wood (like Paulownia, typically dried to 6–12%
moisture content) has a dielectric constant of 2–5, close to that of
plastic (2–4).
            Water’s dielectric constant is high, but the residual
bound water in dried wood contributes minimally to the overall
dielectric effect.
            Your cellulose sanding sealer further reduces moisture
absorption, keeping the wood’s dielectric properties stable.
            In practical terms, inserting a dry, sealed wooden tuning
stick into a coil’s former causes negligible capacitance change, even
at VHF. The effect would be measurable only in hyper-precise lab
settings with sensitive equipment, not in typical tuning scenarios.
    Comparison to Plastic and Ceramic:
        The guy doesn’t explicitly say plastic or ceramic are better
here, but since you mentioned he prefers them, let’s revisit:
            Plastic: Has a dielectric constant similar to dry wood
(~2–4) and no moisture issues, so it’s slightly more consistent in
humid environments. However, your sealed Paulownia is already
moisture-resistant, so the difference is minimal.
            Ceramic: Has a higher dielectric constant (~5–10), which
could actually cause a larger capacitance shift than wood in some
cases, but high-quality ceramic tools are designed to minimize this.
They’re stable but not inherently “better” for all VHF tuning.
            Both materials are non-inductive like wood, so none of
them affect the coil’s inductance. The guy’s focus on water in wood
seems to overemphasize a minor issue while ignoring that plastic and
ceramic aren’t perfect either.

My Take
The internet guy’s got a point about living trees and water transport,
but he’s stretching it to dried, processed wood in a way that doesn’t
hold up for your tuning sticks. Here’s the deal:

    Your Paulownia Sticks: Properly dried and sealed with cellulose
sanding sealer, they’re as good as plastic for most tuning tasks,
including VHF. The residual moisture in sealed wood is so low it won’t
cause noticeable frequency shifts in practical scenarios. The “soda
straws” analogy is irrelevant once the wood is dried and sealed, as
it’s not actively transporting water.
    VHF Sensitivity: At VHF, circuits are pickier, but the dielectric
effect of a dry, sealed wooden stick is negligible compared to the
intended tuning adjustments (e.g., moving a ferrite core). If you were
working at UHF (300 MHz–3 GHz) or microwave frequencies, his concern
might have more weight, but even then, sealed wood is fine for most
hobbyist applications.
    Internet Guy’s Exaggeration: He’s blowing the water issue out of
proportion. Without specific data (e.g., measured frequency shifts
caused by wooden sticks), his claim feels like theoretical nitpicking
rather than a practical problem. Wood has been used for tuning sticks
in RF circuits for decades, even at VHF, with no widespread issues.

Practical Advice
Your Paulownia tuning sticks, sealed with cellulose sanding sealer,
are rock-solid for tuning coils in most circuits, including VHF. The
sealer ensures moisture stays out, keeping the dielectric properties
stable. If you’re working in a super humid environment or
hyper-precise VHF/UHF circuits, you could test plastic sticks for
peace of mind, but there’s no evidence wood’s failing you. Ceramic’s
overkill unless you’re tuning lab-grade equipment.
If you want to double-check, you could:

    Test your sticks in a VHF circuit and measure any frequency shift
with a frequency counter (if you’ve got one). I bet you’ll see no
change beyond the intended tuning.
    Compare with a plastic stick (e.g., nylon or PTFE) to confirm they
behave the same. No need for ceramic unless you’re going pro.

Final Verdict
The guy’s claim is technically grounded but overblown. Your sealed
Paulownia sticks are just as good as plastic or ceramic for practical
tuning, even at VHF. He’s worrying about a non-issue for your use
case. Keep rocking those sticks—you’re golden!"

***********************************************

There is also the importance of honing a tool to the exact size of the
slot, which is *far* easier with a hardwood such as this than with
plastic. So I'll stick with wood, thanks.