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I've taken some measurements: power piston diameter is 8.0 mm, and is made of graphite. Displacer cylinder inner diameter is 25.9 mm, inner height is ~20 mm. The displacer piston (foam) diameter is 24.5 mm and 11 mm in height. I wish you the best of luck making your own. I believe the critical part is the spring mechanism on top which balances out the forces against gravity.

@@RetroTechyNerdyStuff Thank you very much, i really appreciate you taking the time to do that for me,👍👍👍👍 It should be a tremendous help. Just one more thing if i may, when the brass rod on the power piston comes to contact with the lower plastic spring, where abouts in the bore does the actual graphite piston come to in the bore, is it protruding or is it level with the edge of the bore or is it still inside the cylinder by a certain amount. kind regards Kev

No problem; I would estimate the bottom of the power piston is above 3 or 4 mm above the lower edge when it hits the plastic spring at the bottom.

@@RetroTechyNerdyStuff great thats very helpful, thankyou very much. as soon as i get back off holiday i will be in the workshop using your dimensions. again thankyou for your time and help.👍👍👍👍

It smells less than gasoline and you won’t need a complicated carburetter.

@@RetroTechyNerdyStuff do you have a valve to handle air inlet or just handle the butane? (Like diesel engine)

They are the notches in the disc you can see lining up just before opening the lock.

In theory yes, but since the fuel cell produces hydrogen very slowly it would have to run for many hours to fill a balloon. Also, making several litres of hydrogen to fill a ballon would pose a safety risk, so I guess not.

@@RetroTechyNerdyStuff can you make video test show me?

​@@RetroTechyNerdyStuffi savings money to buy it too😢 please test and show me 🙏🥺

The site where I originally bought it does not carry this version anymore. Your best chance is probably searching for it, it seems Amazon do carry some variations of the Galton Board.

I'm glad you found the video useful; I'm aiming to make the channel educational as well as interesting to watch.

Mine didn't initially spin the generator when I got it factory new either. First, I checked for steam leaks. Safety valve first; then the throttle valve. To make it tighter, I lifted the throttle valve's stem and dropped a few drops of steam oil into the valve and then turned it several times to get a tighter seal. Then there's the turbine gears. Make sure everything is running smoothly with almost no friction. It's tempting to oil the gears but I wouldn't as the oil might gum up. Then the generator: try removing the bulb before starting the generator and see if it runs. The turbine needs a lot of pressure to run well, so don't start it until about the time when the safety valve begins to release steam.

Thanks for your kind words. It was fun to make the video and see how the sling unhooks.

I’m afraid I haven’t seen these models offered for sale for some years. I got mine from gyroscope.com many years ago, but they don’t carry them anymore.

The engine was designed by JAXA, the Japanese space agency. I bought it as a kit several years ago. You can find more information in the video's description. Thanks for watching.

The SP8 looks very nice too, and a few years ago Mamod also made a beam engine, the SP8. I too have been somewhat put off by Mamod's quality control. This is the only Mamod engine I've owned and it had several problems out-of-the-box. If I may ask, which specific aspects of the quality put you off buying more?

@@RetroTechyNerdyStuff it would take all day to air my concerns. Check out my shown and special traction engine call something like "has manor changed in the last 8 months". It will give you a good idea. They ate under new ownership now, so maybe things will change. I have a SP8 beam engine. One of the best I had from them, but the general enthusiasts didn't go for it.

@@PLAYINGAROUND You tickled my curiosity so I watched your video. Very interesting, and an excellent walkthrough of the embarrassing mistakes in the workmanship. Mine also had defects, although less severe, probably since it's a less complex engine with fewer things to go wrong. It's sad that quality is sliding with these engine, but to be fair to Mamod in my experience they are not the only steam engine manufacturer which has let the quality slide over the years.

I haven’t measured it yet, but probably around 8-900 rpm under load, and faster without load.

I didn't build it myself. It's made by Kontax in the UK and was bought as a finished engine.

@@RetroTechyNerdyStuff Thanks !

Indeed that is probably very true - just like it happened with the very last typewriters which used plastic (!) letter types. Yet this development was driven by cost-reductions due to competition from cheaper alternatives (electronic versions / computers). But I do wonder what a 21st century mechanical calculator would have looked like if its development would not have been driven by the desire to cut cost but a desire to strive for excellence using 21st century mechanical technology. Frankly, I'm inclined to believe the mechanical calculators were fast approaching the end of the road by the 1970s, and that further developments actually _really_ required an amount of flexibility that only electronics could offer. Implementing features we take for granted, such as negative numbers, decimal-point tracking, square roots and (gosh!) logarithms & exponential functions and trigonometric functions doesn't seem like an easy feat to accomplish using just mechanical parts.

Totally. Pretty soon we will be measuring vehicles by number of candles that run it.

Thanks for watching! Indeed there are several tricks used in computers for computing square roots. Some of them exploit the fact that computers operate on binary numbers. An often overlooked fact is that there is an intimate relationship between square roots and logarithms, in that sqrt(x) = e^(ln(x)/2). Translated into simple terms, it means that if you have access to a logaritm function and exponentiation functions, you can compute the square root of a number by taking the natural or base-10 logaritm of the number, dividing the result by 2 and then raise e or 10 (depending on which logaritm base you used) to the power of the result. This also works with arbitrary roots, say, the 3.7th root of a number. We could calculate that as n'tn root of x = e^(ln(x)/n). And it gets even better: Conversely, since logarithms and square roots are related, the relationship also goes the other way: you can compute logaritms by applying square roots using Euler's method which uses successive approximations and binary search (look it up online) which is a bit slow but is very effective and can be done by pen and pencil. Playing with old calculators like this one can be an intriquing way to rediscover maths that has been largely forgotten since the advent of electronic calculators.

I believe it's the 174 series, at least that's what the accompanying manual says. I have updated the video description with the model information.

I am glad you enjoy the material. Yes, mechanical calculators do have a unique appeal apart from being great conversation pieces. There are many places that you may get second-hand mechanical calculator, although getting a good one and having it arriving in good order can be tricky. Your best bet would be looking in local classified ads or flea markets where you can try before you buy. Online auctions on ebay.de frequently feature some nice specimens, but you will probably pay more. Be sure to get the seller to specify that the calculator is in fully working order. Could be tricky, though, as most people today have absolutely no clue about how these things work. Be prepared to do some cleaning and slight adjustments (like loosening and re-tightening screws) after arrival because shipping can be tough on these heavy devices and cause them to lock up. Keep in mind that many calculators that seem out of order just need relatively simple adjustment and to be cleaned from gummed up oil - this gumming happens with old lubricants and is usually fixable with a little effort. The later Facit calculators like the one featured in the clip is one of the best made mechanical calculators out there, and worked perfectly when I got it after probably 30+ years sitting with no use - but this is the only one that worked perfectly when I received it. Good luck calculator-hunting, and please let me know which model you get :-)

@@RetroTechyNerdyStuff ​ Sorry ichecked on this so late. Looking up on ebay germany the keywords "facit mechanical calculator" i found many and even one almost like yours. 🙂 Edit: however most of them are c1-13 and even some that dont say model, they just say "vintage facit mechanical calculator sweden - FREE UK SHIPPING" and theres even one that says it's for decor! and one of them looks exactly like yours with a little difference in shape. I just noticed there's even a curta handheld mechanical calculator but the price was high almost 1.500 eur. anyway the one i told you about above doesnt have any bids, so i should be able to get it now or later (probably later but i don't talk about that) anyway wish me luck.

I have this one...and will please to gift you as you want to keep it safe but I have no idea, how to ship it to Greece

You are absolutely, right and you are making an excellent point in that regard. I have been noticing this phenomenon myself when playing with the Galton board. Yes, a slower flow would probably help remedying this problem to some extent, but another problem persists: the effect on the balls on each other which occurs because the playing field gets flooded with balls. For the Galton board to work exactly as intended, the balls should not be able to interfere with each other, i.e. each and every "event" should be completely independent. But in reality, if one ball takes one path, it will for a split second prevent another ball from choosing the same place on the path, and the balls will bounce off each other as they collide, affecting the path of both balls. I realize that this is probably an inevitable tradeoff between scientific/mathematical accuracy and practicality when marketing a small and relatively inexpensive Galton board. The phenomenon might also explain why more balls end up in the outer bins than the theory predicts (Pascal's triangle). I'm not convinced that the Galton board fails to adequately demonstrate the theory; indeed the balls don't exclusively interact with the obstruction pegs as intended, but also interact with each other and with the outer casing. Yet these factors seem to simply act as additional sources of randomness which contribute to the bell distribution. After all, a bell is produced, just not exclusively by the balls' interaction with the pegs as the Galton board's design prescribes. You may want to stay tuned for an upcoming clip of another, much larger Galton board on which the manufacturer has designed it differently to help prevent these issues.