My diaphragm piston air engine with rotary valve
Fri 8 November 2024
I made an air engine with a diaphragm piston and a rotary valve. It was inspired by
a video from Robert Murray-Smith,
but improves on the design. Read more
A self-aligning Boggle board
Wed 25 October 2023
Earlier this year Charlie challenged me to make a Boggle board that always leaves
the letters upright, and this week I have succeeded. Read more
A quick 3d-printed light gate
Thu 4 May 2023
I need to affix a rotary encoder to my oscillating steam engine to
measure the crank rotation, so that I can plot pressure-volume diagrams from the real engine to compare to
the simulation. Rather than buy a rotary encoder,
I decided to make a light gate and slotted disc myself. I haven't done the slotted disc yet, but it will be
a pretty trivial 3d print. Read more
Cheating at chess with a computer for my shoes
Sat 30 July 2022
I have come up with a new way to win at chess:
I have connected up a Raspberry Pi Zero in my pocket to some buttons and vibration motors in my shoes,
so that I can surreptitiously communicate with a chess engine running on the Pi. The project is called "Sockfish" because
it's a way to operate Stockfish with your socks. Read more
Packing puzzle: Six Fit
Thu 17 March 2022
I've designed a new 2d packing puzzle. It's called "Six Fit" and you have to fit 6 pentominoes into a rectangular tray. Read more
Party Puzzling: themed puzzle sets for special occasions
Thu 24 February 2022
Emma and I are now selling themed puzzle sets for use as entertaining party favours
for events like weddings, and stag and hen parties. The idea is that you'd
buy enough to give one to every attendee, and people who want to can try
to solve it, and regardless they can take it home afterwards. There's also a competitive
element: each puzzle has a QR code inside which the successful player can scan to add their
name, and solve time, to the event's private online leaderboard. Read more
An Arduino-based USB interface to the Psion Organiser II
Sat 5 February 2022
I built a hacky USB interface to the Psion Organiser II that
lets you send messages to it over USB serial via an Arduino Nano. It involves the organiser executing machine code stored in a string
in its BASIC-like language, and it totally abuses the CPU's bus design. But it's simple and it works. Read more
Bubble packing puzzle
Tue 23 November 2021
I designed a new puzzle this morning, it's a relatively simple packing puzzle where you have to fit
21 circle-ish pieces into a case. Read more
Lightweight and robust quadcopter guards
Tue 16 November 2021
I recently built a small quadcopter and have been flying it around the house.
Predictably, I have been crashing into the walls a lot. I wanted to put some rotor guards on
to stop the propellers from scratching things, and I have come up with a 3d-printable rotor guard design that I think is quite elegant. Read more
I made an adjustable loaded die
Tue 2 November 2021
I made a loaded die with a tiny servo hidden inside that can move the weight around to change the
distribution of roll probabilities. Read more
Fixing my tablesaw tilt mechanism
Fri 1 October 2021
I have a Lumberjack
TS254SE tablesaw. It's not a high-end tablesaw, but it was relatively cheap and it works well enough. Except for the blade tilt mechanism. Read more
Towards a high-resolution grid of tiny electromagnets
Tue 21 September 2021
I'd like to build a high-resolution grid of tiny electromagnets. It would work a lot like an LED matrix display, except instead
of the pixels emitting light, they emit magnetic fields. I have made a small proof-of-concept, but I need help
to learn more physics to improve the strength of the field and the density of the pixels. Read more
A method and apparatus for polishing shafts
Sat 1 May 2021
I have invented a new tool. From time to time, I expect you, like me, need to sand down the outside of a piece of round
bar. I expect you, like me, chuck the round bar in a drill or a lathe, spin it up, and then hold sandpaper
against it to sand it. This works fine when you are able to spin the round bar, but sometimes the bar is
already connected to something big or inconvenient and you are not able to spin it, and you are left wondering
what to do. Read more
I want to cast some rings
Thu 21 January 2021
Emma and I are getting married later this year, which means we need to acquire some wedding rings.
I initially wanted to get rings made of some exotic alloy like Inconel,
but now I think I'd like to cast them myself out of gold, which means I need to learn how to cast rings. If you
know how to cast rings, perhaps you can help me learn. Read more
All the gears, no ideas: an escape room puzzle
Fri 18 December 2020
I designed a puzzle for an escape room. The company ended up not wanting to pay for it, but I thought the puzzle was interesting
enough to be worth making for myself anyway. Read more
I made an optical inline fuel sensor
Mon 28 September 2020
We could automatically detect whether the racing mower is about to run out of fuel
by shining a light through a section of clear fuel hose with a sensor on the other side. The idea is
that when the fuel has disappeared the received light intensity will change, and we can detect this with a microcontroller. We can then turn on an LED on the dashboard to alert the driver
so that he makes a pit stop instead of spluttering to a halt at the opposite end of the track. Read more
I made a mechanical keyboard with 3d-printed switches
Fri 7 August 2020
The keyboard is done! This is basically the result of what I've been working on for the past 2 months, which has
involved 3 iterations of testing machines, over 100 printed switches, and now finally a keyboard that I can type on.
Unfortunately it is not a very good keyboard, but you can't win them all. Read more
Another new switch tester, test results, and thoughts on the keyboard design
Wed 15 July 2020
Just an update on the keyboard switch project. I've built the new 10-way testing machine, ran a (somewhat inconclusive) test to work out the best
thickness for the leaf springs, and thought a bit on how I'm going to design the actual keyboard. Read more
Secrets of the Hanayama Cast Marble
Wed 8 July 2020
Cast Marble is a mechanical puzzle sold by Hanayama.
It was invented by Bram Cohen (who you may recognise as the
inventor of BitTorrent) and Oskar
van Deventer, who has an interesting YouTube channel where he regularly posts
new puzzle designs. Read more
I made a macro keypad with 3d-printed switches
Mon 6 July 2020
Latest on the 3d-printed keyboard switch project: I've reached a switch design that I think is probably reliable enough,
and I've put 3 of them together to form a macro keypad just to see how it all goes together before I commit to a
full keyboard. I don't have a number for how many presses the switch lasts, other than to say that
the motor on the testing machine stopped working before the switch did (after about 250,000 presses). Read more
Keyboard switch progress & test results
Thu 25 June 2020
Status on the 3d-printable keyboard switch is that the latest test managed 110,000 presses
before failure, on the spinning cam tester. Read more
A better automatic keyboard switch tester
Sat 20 June 2020
Since breaking the last switch, I re-printed the same design in PETG
to see if it would last any longer, and it did! It reached over 100,000 presses under the gentle testing regime without
showing any failures, a big improvement over failing at 13,907. Read more
I broke my first 3D-printed keyboard switch
Tue 16 June 2020
Overnight I did my first test of a homemade keyboard switch on the automatic tester.
The spring in the switch broke after 13907 presses. That makes Martin our
competition winner, with a guess of 10000. Read more
Automatic keyboard switch tester
Sun 14 June 2020
I'm working on designing an open source 3D-printable keyboard switch at the moment,
with a view to eventually making my own mechanical keyboard using minimal off-the-shelf
components (just an Arduino, wire, and diodes, with homemade parts for switches, keycaps, and case). I have not
made a keyboard yet, but yesterday I made a device to test how many presses a switch can withstand
before it stops working. Read more
Autopatzer: my automatic chess board
Wed 6 May 2020
My automatic chess board (the "Autopatzer") has reached the point where last night I was able to
play its first online game against a real person using lichess's Boards API. Read more
I built an antweight combat robot
Mon 27 January 2020
If you've ever seen Robot Wars or BattleBots,
you'll know what a combat robot is. An antweight combat robot is the same concept, except it has to weigh no more than 150g and fit inside a 4-inch cube. I've
built one, called "Wedge of Glory", and have my first competition this weekend! Read more
My Arduino-based industrial process controller
Sun 1 September 2019
For my 3d metal printing project, I need the sintering furnace to stick to a pre-defined temperature
profile. Unfortunately, the controller that my furnace came with only allows you to set a constant temperature. It maintains
a constant temperature very well, but the operator frequently has to manually update the temperature in order to stick to the defined profile. Read more
Home 3d metal printing: first results
Mon 12 August 2019
A couple of weeks ago I learnt about an interesting 3d metal printing process,
from a company selling it for $100k USD, and speculated that it might be DIY-able for much less. Well I now have some
promising first results. Read more
An interesting 3d metal printing process (help wanted)
Sun 28 July 2019
I recently learnt about the Markforged Metal-X 3d printer from a post on 3DP Reviews. It costs
$100k USD, and can print metal objects. As far as I can tell, it is essentially an ordinary FDM printer, with a special filament that contains
a high percentage of metal powder held together with a "binder". After printing, the part is washed in a solvent to remove most of the binder, and finally it is
heated in a furnace to sinter the metal powder together. Read more
How to make a rev limiter with an Arduino
Mon 22 July 2019
My racing mower has a tendency to
over-rev on long straights. To avoid damaging the engine, we have been lifting off the throttle, but a more reliable
solution would be an electronic rev limiter.
I did buy a commercial rev limiter made by AccuSpark, but was unable to fit
it to my mower because the AccuSpark unit needs access to both sides of the ignition coil, and my ignition coil
is inaccessible, inside a black box with all the other ignition electronics. So my solution was to make a rev limiter with an Arduino. Read more
Puzzle Drawers
Sun 17 March 2019
For the last ~3 weeks I've been working on a chest of drawers. This is no ordinary chest of drawers, they are puzzle drawers.
The idea is that the puzzler is presented with one of the drawers already open, and the goal is to manipulate the chest into
a configuration where all of the drawers are closed. With a typical chest of drawers, this would be easy: just close the
drawer that is open. In the puzzle drawers, there are 3d-printed internal mechanisms linking the drawers together. Read more
The Wheatstone Cryptograph
Fri 15 February 2019
A few weeks ago I came up with an idea for a simple encryption device, then found that it had already been invented
by Sir Charles Wheatstone around the
1860s. I ended up designing and 3d printing a replica of Wheatstone's cryptograph. Read more
Towards a Better Pythagorean Cup
Fri 4 January 2019
There was an article on Hacker News the other day by David Richeson entitled
Make Your Own Pythagorean Cup.
A Pythagorean cup is a cup with a built-in siphon. Supposedly invented by Pythagoras, the cup functions just
like an ordinary cup as long as it is only filled to a certain level. If anyone gets greedy and tries to take
too much wine, the level rises above the top of the siphon, which causes the siphon to self-start, and the
greedy person is punished by having the entire contents of the cup dumped into their lap. Read more
First Light in the PiKon telescope
Sun 16 December 2018
On Thursday night I had an opportunity to try out my motorised PiKon
telescope for the first time. Emma and I drove to a cemetery that is about 5 minutes away. It is not an ideal
astronomy spot, but it is better than our back garden as it is a bit further from trees, tall buildings, and street lights. Read more
My PiKon telescope hardware
Mon 3 December 2018
Since the last post I've been working on the hardware of my telescope.
I think the hardware is basically done, I just have a bit more software to write, and then need to wait for a convenient and
cloud-free night in which to try it out. Read more
Ramblings About a Computerised Telescope
Mon 19 November 2018
The PiKon telescope is a brilliant design for a cheap but powerful telescope
using 3d printed parts and a Raspberry Pi. It is a Newtonian
reflector telescope, designed to be mounted and aimed with an ordinary camera tripod,
and then the Raspberry Pi camera is used to capture images. It uses a relatively inexpensive concave "spherical" mirror
for the primary mirror, and has no secondary mirror: the Pi camera is small enough that it is simply mounted in
the centre of the tube and captures light where the secondary mirror would normally be placed. Read more
Introduction to Isopath
Sat 30 June 2018
Isopath is a game invented by YouTube user pocket83.
The game was initially presented in this video
where pocket83 shows how he made the board and tiles, and then explains the game rules from 15:45 onwards.
Isopath is a zero-sum, turn-based, deterministc, perfect-information game, which puts it in the same class
as games like chess, draughts, go, noughts-and-crosses, etc. Read more
My homemade ebike control panel
Fri 1 June 2018
I wrote before about dismantling the control panel from my ebike to find out how it works, and had some ideas for an improved design. Read more
I designed a trick chess piece with hidden compartments
Sun 4 February 2018
It's quite easy to model a traditional chess piece (apart from a knight) using CAD software. You basically just have to draw a sketch of the outline and revolve
it around its centre. I modelled, and 3d printed, a Queen that includes some hidden compartments for storing small bits of paper, e.g. containing passwords or Bitcoin
keys. Read more
Magnetic cubes puzzle: In practice
Mon 22 January 2018
I've put together a physical version of the magnetic cubes puzzle and
have spent a good few hours playing with it. (You don't need to have read that post in order for this one to
make sense, but it might help, and it's certainly worth having a look at the table that labels the different cube configurations).
I haven't yet managed to solve it without consulting a computer. Read more
How to control a digital speedometer
Tue 12 December 2017
As part of my YX140 scooter project
(now finished)
I discovered that the scooter's speedometer is controlled digitally. There was a sensor in the original engine
which generated pulses to signal the speed of rotation of the gearbox output shaft.
The new engine has no such sensor, so I had to do a little electronics to make the speedo work. Read more
How to create 3d-printed stencils for spray-painting
Mon 3 July 2017
I wanted to make some custom spray-painting stencils. I've done it before by printing on paper
and cutting out the shapes, but found it to be laborious and time-consuming. Also the stencils don't last for more than
a couple of uses before the paper gets too soggy. Read more
I bought an extremely cheap 3d printer and it's great
Wed 25 January 2017
I had a look on eBay last week to see what sort of price 3d printers are going for
these days, and was surprised to find some on offer for £150. At that price it's
obviously not going to be very good, but should be fun anyway. Read more