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.   hunkin





A series of youtube guides for designers and makers


If you enjoy my 'Secret Life of Components' videos, please support the project

I'm not starving, but it encourages me to keep at it.. 





CHAIN                  Thursday 4th March
LEDs                    Thursday 11th March
HINGES               Thursday 18th March
SWITCHES          Thursday 25th March
SPRINGS            Thursday 1st April
CONNECTORS   Thursday 8th April
GLUE                  Thursday 15th April
BEARINGS         Thursday 22nd April

(I'll also be releasing the new re-mastered versions of the original Secret Life of Machines series. Working from a set of PAL tapes made directly from the original 16mm prints and upscaled with machine learning by Norman Margolus using software from Topaz labs. They look fabulous.)


I enjoy reading all the comments but apologize that there are so many I canít answer individually. Iím delighted that my new videos have been so enthusiastically received, which is reflected in the majority of the comments. The videos arenít perfect though so below each video Iíve compiled the comments about things I omitted or people thought were misleading. A few comments added wonderful additional information so Iíve included them as well. 



Several people defended the use of Ďspring clipsí to join chain. I should have said my problems with the clips are just with small 6mm and 8mm sizes I mostly use - for bike chain and larger sizes the spring clips work fine. Two people described their technique for fitting the clips, using long nose pliers between the clip and a pin, which helps prevent the clip springing off.

It was also a bit misleading to say that chain Ďstretchesí with wear. It does get longer but this is due to the wear in the bushes and pins making them a looser fit rather than the steel actually stretching.

Several enthusiasts wrote about ínon-greasyí bike lubricants. I hadnít come across them, but obviously a step forward.

Di Zolytan wrote that bike chain efficiency reduces noticeably with small sprockets, under 16 teeth. 8 teeth is the generally accepted minimum number of teeth for a roller chain sprocket, though I did once get a 6 tooth sprocket working on my gravity escapement clock where I needed large reduction ratios.

Juncus Bufonius reminded me about the ancient Romans use of chains of bronze water buckets.

Two people wrote to say that the tiny fusee chain was traditionally made by children working in appalling conditions!

Flurng desribes an ingenious use of chain I didnít know about to regulate the depth of deep sea bathyscapes. Heavy chain dangles below the craft to weigh it down. Once the chain touches the sea bed any further increase in depth reduce the weight of chain pulling down the craft. This also reminded me of watching a large ship being launched. I was down near the rudder and as the hull started to slide into the water there was an extraordinary noise. I hadnít noticed the hundreds of tons of huge chain which were being dragged into water along with the hull to act as a brake.

Flurng added this wonderful addition as well: One of the most novel and unique implementation of chains that I've seen was on the Wright Brothers' Wright Flyer craft - on that aircraft, the twin propellers were driven from the same pulley, yet the two blades were counter-rotatating (one clockwise, one counter-clockwise). They achieved this by criss-crossing the left propeller drive chain, so that it moved in a "figure 8" manner. The design included "guide tubes" for the chain, to prevent it from snagging on itself as it crossed over in the mid-point! Truly ingenious!

I should of course have included chainsaw chain, particularly the difficulty of keeping the teeth sharp. I donít often use my chainsaw and have never found a good solution so I just keep a few new spare chains. My friend Andy who uses them more often swears by an angle grinder with a 3mm cutting disc, just touching each tooth gently.

Its hard to know where to draw the line, the video could easily have been twice as long. Iím particularly obsessed by jewellry chain making machines. A bit like hand sewing machines, a roll of thin wire goes in one end and perfectly formed chain comes out the other. A friend has one which I find endlessly fascinating and beautiful to watch.



Quite a few people criticised my sum for working out the value of the resistor to put in series with an LED. To get the maximum brightness, the forward voltage of the LED (part of the spec) can be deducted from the supply voltage. Personally I prefer not to run LEDs to close to their max as I have had many fail over the years, mainly because of overheating. Also their brightness does not visibly diminish dropping the power by 20%. However the criticism is very valid when the power voltage not much higher than the LED voltage. If I had used a 6v supply for my 3.3v power LED, my rough sum would have resulted in a resistance twice as high.

Apparently its not strictly true that LEDs canít be harmed by connecting them the wrong way round. High reverse voltages and even low voltages on some newer surface mount LEDs can fry them.

Donald Sayers reminded me that a single flashing LED can be used to flash a whole chain of LEDs wired in series. I wish I had included this. Even better, the wonderful Evil Mad Scientists have a simple circuit using a flickering tealight LED as the base of a transistor circuit to make a high power flickering circuit. I used this on the sign at the top of my i-Zombie machine. (

Mark Harriss had managed to see light with a wire touching 36grit silicon carbide abrasive. It required about 1amp and 20 volts, and produced a variety of different colours.

Several people wrote to explain the warm LED filament household lights. They are strips of tiny surface mount LEDs covered by silicone and phosphors. They require about 70vdc which why I hadnít managed to get them to light up! One person added that they were invented in China, before being copied by Philips and GE. Also that the strips have four blue LEDs and one red one in series, with the phosphors blending them to the warm yellow.

Vincent Sullivan wrote that the numbering system used for surface mount LEDs referring to their size in mm is also used for other components, particularly coin cells. So for example a 2030 cell is 20mm diameter and 3 mm thick.

Gordon Slater uses a 4 inch bit of wood with a blunted sewing machine needle on the end to rest (or lightly clamp) on surface mount LEDs while soldering. Extra flux was another suggestion.

Electra Flarefire wrote that the clear coating of waterproof LEDs strips is clear PVC, not silicone. Of course, this is why they are completely clear, not translucent. It also explains my experience of the coating becoming stiffer and brittle with age as the plasticisers in the PVC evaporate over time.

Tom Z added a great fact about the bonkers over-engineering of some BMW headlights which use blue lasers aimed at phosphors to create the sharp focused beam.




Iím embarrassed that I said video projector colours are Yellow, Cyan and Magenta after misunderstanding the Wikipedia entry. Video images are all based on Red Green Blue. It is a bit confusing because projectors with the Texas Instruments tilting mirror chips use several different systems and some have a spinning colour wheel of dichroic CMYK glass mirrors. I now guess this acts as a filter for the white source, allowing through the complementary RGB colours.

Peter Van Ginneken wrote that the Rotterdam flood barrier does not have any wheels of rollers along its length. Instead it has buoyancy tanks so it literally floats out into position. The tanks are then flooded, lowering the gates to the bottom and forming a watertight seal. So ingenious as he says.

Gimp pins are still used for upholstery and remain easily available.

Several people were appalled that I used a claw hammer on the chisel to rebate the door hinge. A mallet is better because the wider head makes it harder to miss so its easier to your eye on the work. But my hammer just feels like an extension of my arm, its something I just use without thinking.

Other people worried about having my fingers so close when I was welding. The video makes it look more alarming than it is is reality. Iíve done tack welds like this for 40 years without getting a bad burn. Picking up hot parts up forgetting Iíve just welded them is more of a problem, I am now literally very thick skinned.



Iím delighted that many people commented on the giant microswitch because Rex made it 30 years ago for our Secret Life of the Lift film. Far too good to throw out its been waiting in my stores for this moment of glory. Its made of layers of MDF, cut to shape on a bandsaw.

Although no one directly explained why electricity sub-station switches move so slowly two people wrote saying Ďthese are isolators, not breakersí. This is the key. The power is normally switched by the breakers, which are totally enclosed and do move fast using compressed sulphur Hexafluoride gas to quench the arc. Isolators are normally used when the supply is turned off, though obviously as in the video clip there are exceptions. Nick Abbot wrote: The high voltage switches move slowly to prevent thunder. If they moved at high speed, there would still be arcing but it would be a loud cracking sound, like thunder. Plus, the slow moving switches increase the power to the line slower, using the air gap as a resistor.

Scamin Sam rightly told I got the suppressor circuit wrong. I havenít used one for a while and forgot that the resistor goes in parallel with the capacitor, not in series. The idea is that resistor drains the charge out of the capacitor so its fully discharged when the contact is made or broken. I did use to use them correctly, but the contacts in switches and relays still arced when switching DC motors, though possibly not quite so much.

A lot of people wrote to explain my mystery mercury wall switches. They are explosion proof because the arc is totally enclosed in the glass enclosure. One person had a mercury delay switch, just a tiny tube to restrict the flow form one contact to the other. A retired surgeon told me that operating theatres always have explosion proof switches because for long operations an inflammable anaesthetic is used and that there have been rare cases of patients exploding.

Linux Lovah asked why are DC ratings for switches so much lower than their AC rating (on the toggle switch I showed in the video the AC rating was 15 amps and the DC only 1 amp). Such a good question. I have a possible explanation but do write if Iím wrong. As AC has zero voltage 100 times a second, or 120 for countries with 60hz supplies like the US, this probably encourages the arc to extinguish. I canít resist adding this related tale. At the end of the 19th century Edison was championing his DC supply system against Westinghouseís AC system. Both did experiments electrocuting animals to try to prove their system was the safest. In states that used Westinghouseís system for the electric chair, Edison claimed the prisoners had been ĎWestinghousedí. But with the benefit of hindsight AC was safer because the reversal of the current has the involuntary effect on muscles of repelling and releasing grip, whereas DC just tightens the grip.









Its now 30 years since I finished making ĎThe Secret Life of Machinesí TV series with Rex Garrod. Since then Iíve spent most of my time happily in my workshop, mainly making arcade machines for my two arcades, one in central London and the other on Southwold pier. Iíve been very fortunate to have had such freedom to make exactly what I like for so long.

For some Iíd been wanting to find a way of passing on something of what Iíve learnt about making things. Covid 19 brought the idea into focus and it has been the perfect time to do it without distractions. The videos bring together two aspects of my career Ė explaining things and making things.

Its impossible to teach Ďexperienceí. I obviously have the experience to make complicated machines but I donít know exactly what it is that I know. So much of it is non verbal or Ďtacití. I work with my hands and at times they just seem to take over.

In the past, when people asked me how to learn practical skills, Iíve told them they just have to make things badly to start with but to keep going and they will improve. I made things badly for the first half of my life. However, I now learn a lot from watching practical youtube videos and realise that they can teach the sort of informal tips that used to be part of traditional apprenticeships. So Iím delighted to be contributing to this wonderful new learning resource! I hope my videos, each about 45 minutes long, are entertaining enough to be fun for beginners, but also detailed enough to be useful for pros.

Working out how to film them was interesting. My wife has a Canon Legria Hg30 which is a great camera. It orginally cost about £1200 but the model is now 8 years old and on Ebay are now about £400 so I bought a couple. At first I thought my assistant, Bill Parks, could be the cameraman. But he only comes on Wednesdays and I gradually found the flexibility of filming whenever I wanted was essential. So I experimented with various camera setups to do the filming myself, making a rig to suspend the 'closeup' camera from the roof of my workshop. Then I have a monitor so I can see  the closeup camera image to check things are in frame. At first I mounted it behind my shoulder but then my head kept getting in shot (you can see this in the Bearings episode). I changed to having the closeup camera near to the other camera. This makes the picture in the monitor very confusing because my hands moved in the opposite direction to their actual movement. The breakthrough was turning the monitor upsidedown - surprisingly this makes the movements completely intuitive. 

Lighting was relatively simple. I really like the natural light in my workshop with the big skylights. To make 'natural 'light simple to work with, I added translucent blinds to the skylights to cut out direct sunlight. On dark days I found that a couple of 600mm square LED office lights (intended for suspended ceilings) mounted on tripods shining up at the white painted roof cast an even light which didn't look too unnatural. 

The animations at the start of each episode were amazingly quick. The slowest part was arranging all my components to make the title. A still camera mounted above the table then started taking photos every few seconds.( I connected the remote control to a microcontroller) while I went round the table gradually breaking up the word and creating chaos. The actual filming never took more than 15 minutes. Obviously I then reversed the film in the edit. The films were edited in Premiere 6, the last version that could be bought outright before Adobe switched to monthly rentals.   





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