# To draw a tempo, draw the pendulum three times, not once

> A metronome's pendulum is one solid rod. Drawn once it's a photograph of a stopped machine — drawn three times, faint at the sides, it's motion held still.

August 19, 2026 · https://justog.club/stories/metronome-pendulum-arc

One metronome, drawn front-on. Its pendulum appears three times in the same print — swung hard
left, centred, swung hard right — with the outer two faint and only the centre one drawn solid.

At the top and bottom of the scale behind it, two numbers: 208, 40.

A pendulum only ever occupies one position at a time. This print shows all three anyway, because
that's the only way to draw what it does rather than what it is.

## What is a metronome's pendulum actually doing?

Swinging at a fixed rate that can be changed by sliding a weight up or down its length.

Move the weight toward the pivot and it swings faster; move it toward the tip and it slows down —
the same relationship a longer pendulum on a clock has to a shorter one, applied on purpose and
made adjustable. The scale behind it is a ruler for that weight's position, marked in beats per
minute rather than centimetres.

## Why draw the pendulum three times instead of once?

Because one position looks like a stopped machine, and three positions look like a running one.

A single static drawing of a metronome tells you it exists, not that it works. Placing the same rod
at three points along its swing, with the outer two faded back, borrows the trick a comic strip uses
to show a thrown punch or a closing door — the eye reads the fade as time passing rather than as
three separate objects. It's the only way to put motion into something that has to sit still once
it's printed.

## What do 40 and 208 mark?

The slowest and fastest settings on the scale, in beats per minute.

Forty is a heavy, spaced-out beat; two hundred and eight is close to a flutter. The range sits
where it does because it's built around a human pulse at rest and a human pulse working hard, which
is what a metronome is ultimately measuring a performer against — not an abstract range chosen for
round numbers, but one bounded by what a body can actually keep time to.

## Can a real metronome's scale or brand go on the shirt?

The beats-per-minute numbers are physics, and nobody owns a rate. A maker's own case design and
badge are a different matter.

Forty and two hundred and eight describe a swing rate, the same way a speed limit describes a
speed — nobody can claim it. What a specific manufacturer owns is their case shape, their printed
scale's typeface and their name on the front, which is licensable the ordinary way a
[real amp's own front panel](/stories/amp-stack-front-on) would be. Left generic, this print
stays a tempo instrument rather than one company's product.

## Does this work for something other than a musician's practice room?

Anything measured against a steady beat rather than a clock reads the same way.

A runner training to a cadence, a conductor, a drummer without a kit to hand — all of them are
using the same idea a metronome formalises: a fixed, repeating rate held against a moving body.
The print doesn't need to specify which of those it's for, because the object does the same job
either way and [a hi-hat drawn in its two states](/stories/hi-hat-closed-and-open) is making
much the same argument about a gap standing in for motion.

## Isn't a mechanical metronome an odd thing to print when most people use an app now?

The mechanism doesn't depend on which one is more common.

A phone app keeps the same time a wind-up metronome does; it just doesn't have a rod to draw. The
wind-up version is the one with a visible moving part, which is the entire reason it's the one worth
putting on a shirt — there's nothing to draw about a beep.

## Does it print well?

Yes — three thin outlines of the same shape at different fade levels is a controlled effect, not a
complicated one.

Bone or a pale neutral keeps the solid centre pendulum sharp in black while the two faded copies sit
back in a lighter tint of the same colour rather than a second ink. Red for the scale numbers keeps
40 and 208 legible without competing with the pendulum for attention.

## How do I get one made?

Describe the metronome at [JustOG](/) — the scale range, which beat to hold solid, and how faint
the other two should be. Pick a direction, drag the crop frame, see it composited on the real
garment, and it's made to order and shipped.

Designs other people have published are in the [shop](/shop).

Three positions of one rod, and only the middle one is where it actually is right now.