Dan Maloney
OK folks, here we go! I'm Dan, I'll be moderating today along with Dusan as we welcome Quinn Dunki back to the Hack Chat. We had Quinn on a couple of years ago to talk about machining in general, but now we want to get into specifics of her steam engine and boiler builds, which are all pretty cool.
Hi Quinn, are you on board yet?
Oh hai
Hi Dan
Hello and welcome everyone
hey quinn
Hey there! Thanks for taking time out from what's probably a hectic time, what with the move and all. Getting settled?
Getting there! It's an all consuming project unto itself. Very close to making chips in my shop again though.
Hey Charlie! :D
Cool! So where did the interest in model steam engineering come from?
:)
I've always loved steam engines, and I learned about ten years ago that building them yourself is a thing people do (waits for British people to all finish sighing). I started watching machining videos on YouTube and it's sort of a slippery slope from there.
I got into machining with the goal of building a working engine (among other things), but then once you're in the engines start getting bigger and more complex until you wake up one day surrounded by cast iron and wondering how you got here.
Seems like an area that might be hard to just jump into, what with the danger of boilers and all. What's the "on-ramp" to steam look like for the newbie?
The truth is that steam is a great fit for hobby machining for the exact same reason it started the industrial revolution- these engines are very forgiving and pretty easy to make with mediocre equipment. The boilers, yes, are fraught, but you can run on them on compressed air as well, which many people stick to.
Internal combustion engines are much more difficult- if you don't nail every tolerance, they immediately self-destruct (possibly passing a rod through your eye in the process). Steam engines fail gracefully- the better made they are, the more efficient they are. But to quote the great Emma Ritson, "they always run". It's honestly pretty difficult to build a steam engine that won't at least run, even if it wastes a lot of air and makes no real power.
My brother, now passed on, was great working on and building his own steam engines both water tube and fire tube types. He would have loved to sit in on todays chat.
Plus they are simple enough beasts that you can make them with simple manual machine tools and few setups. That all makes them ideal as hobby machining projects. A little wobbler engine from bar stock is something anyone can built on a mini-lathe with basically no experience.
Sounds like steam power could be a civilization rebooting technology, should we ever have need of that *looks nervously at the news*
Like the old saying goes.... if the zombie apocalypse ever happens, find the person with the lathe.
always have a friend with a lathe in your local group in case of collapse, if you decide you want to live in that outcome.
What kind of pressures are you using out of interest? And does that vary much? Also is there any risk of something blowing up and shooting bits of metal?
*hands Charlie a Coke*
The Gingery books are probably cheap insurance, too. Just saying.
For pressures, it's actually a point of pride how low your engine will run on. An engine that can idle on single-digit PSI is the goal. To make real power and do real work (say to light a lightbulb) you're look at more like 30-60 psi. Scale locomotives that pull people around typically run on about 100 PSI. Beyond that you're into diminishing returns, honestly.
Many full-size steam locomotives didn't run on much more than 150psi. It's more about volume of steam than pressure at that point. The boiler has to produce sufficient volume to keep up with the cylinders, which is in tension with pressure. More pressure means less volume, so there's a balance around 150 psi. Superheated steam is a different ballgame, and there were some later engines that ran north of 800 psi
The hard part of rebooting civilisation would be that we have already mined the accessible coal and iron ore.
The real limit on pressures as a hobbyist is local regulations. Every jurisdiction is different, but typically you can't go bigger than about 100 PSI or 6" in diameter on a boiler before you need to be licensed and have it annually inspected.
1- Friend with a lathe
2- friend with a generator to run lathe
oh that's interesting re. single digit PSI for idling :) didn't realise that re. diminishing returns either. Is super heated steam something that's used on trains, or some kind of fixed engines?
re: License and inspection -- what authority would that fall under? Is that like a Fire Marshall thing?
Locomotives universally run superheated steam. Stationary boilers less commonly do, but some do. To quote Keith Appleton, locomotives are the Ferraris of steam. They leverage every technology and trick for maximum performance. Superheated steam is a huge power win, but it's a level of technical challenge that is notable higher.
Hi Quinn, love your Videos by the way, they actually got me to get a lathe and can't wait for it to arrive and get set up. Will you attempt an internal combustion engine with your tools or are there other interesting (steam) engines designs you'd like to build?
@Nicolas Tremblay Treadle lathes are a thing. Look at eBay 204014445765 for example
Boiler inspection is handled by different agencies depending on where you live. It may be at the city level, or state, or province, or national. Boilers are still in wide use in all sorts of industry of course, so it's still an active thing. We don't run reciprocating steam engines any more, but much of our world still runs on boilers.
Thanks @Rudgas :D
Is steam turbine construction possible without high precision machining?
However don't expect government boiler inspectors to give you the time of day as a model engineer. Most of them, in my experience, are totally unaware this is a thing. The best resource is a local model engineering club or society. They often have a boiler inspection and certification procedure of their own and can walk you through it if you want to build big.
Hi Quinn! It looks like you mostly build kit engines. Do you have any plans to design and build your own at some point?
I'm sure you could build a working steam turbine. At the end of the day it is just a fan blade that you're pointing steam at. How efficient it is and how much power it makes is another story. Like jet engines, it's more of a materials problem than a machining problem.
@Mark J Hughes The first two engines I built were from bar stock. I built the first casting kit engine because I wanted to try working with castings. Then PM Research sent me the big one so I'm working on that now. After that I plan to go back to bar stock.
Sweet!
What are some other "bucket-list" projects (assuming you've completed the move and have a working shop again)
A friend of mine is working on a scale model internal combustion engine. But he's been at it for 15 years and still hasn't got it running. But then he did have to work out how to make 1/4 scale fuel injectors and spark plugs. He has made a trial cylinder head (the engine he is modelling is a Ferrari V10 F1 engine)
That would have made a very boring YouTube series, I think.
The top of the bucket list is certainly a locomotive. I have all of Kozo Hiraoka's books and I'll likely attempt one of those at some point. There are some really interesting complex valve engines that I want to look at as well. Corliss engines are amazing. I'd like to build a Sterling engine as well. They are an amazing solution still looking for a problem after a hundred years. :D
@Andy Pugh There is a scale V10 Viper engine that made the rounds on YT a while back, complete with working fuel injection, electric start, and Roots supercharger. It's a stunning achievement that I can only aspire to.
Turbines usually run with some superheat, as well, because you don't want much of your steam to actually condense in the turbine - in that domain a droplet of water is a bit like a bullet and will shred the turbine, the number I recall being told when studying was something like going 5% into the liquid phase, tops.
Yah, for sure they need very dry steam
There is another YouTube channel (2-stroke stuffing) that is trying a pair of Corliss-style valve. Unlike Corliss they are continually rotating, so not variable cutoff etc. But it does mean that he has rotating exhaust pipes and actual "muffler bearings" :-)
I recently saw someone in the YouTube machining community do a project using castings made by a foundry from 3D-printed models -- can't recall who it was or what the build was about. But, that raises the possibility of farming out cast iron parts. Any interest in doing that?
Any recommendations for steam engine that can be built with a lathe only, no milling machine?
@Dan Maloney I know you are not asking me, but I have been doing exaclty that for a few years now. 3D-printing has revolutiuonised home pattern-making as things like off-sides are really easy.
Yes, for sure! Foundry work is the next step for a lot of model engineers and I'm very interested in it. Aluminum and bronze are quite accessible to the home gamer. Iron is next level though, in terms of equipment and danger. Not for the feint of heart. In particular I am interested in Lost PLA casting, which is a great use of 3D printing, IMHO.
@mwfeurtado I have a wobbler on my blog that can be built with only a lathe. I plan to do another one on my channel soon, since it's something a lot of people have asked for.
(I send mine out to a foundry. AJD charges £10/kg for castings with about a one-week turnaround, and seems to enjoy one-offs)
For folks in the US, shout out to Windy Hill Foundry if you want small stuff done. My friend Clarke over there is swell. :D
Lost Resin from SLA prints seems to give some great detail, although I've only seen it for Jewelry yet.
The Rough & Tumble Historical Association has a 2/3 scale Shay locomotive which was built from scratch. https://roughandtumble.org/viewreference/74/volunteerprojects
A quick note on superheated steam, since there was interest in it. For anyone not aware, normally boilers make wet steam, which is steam (invisible hot gas) mixed with a lot of water vapor. This is "steam" you can see. Real steam is invisible and a lot hotter, which is known as superheated. To make it, you take wet steam (aka saturated steam) from the boiler, and pass it through the firebox (heat source) a second time in stainless steel pipes (which can take more heat than copper). This heats the steam a lot more and dries it out. You get pure steam with little or no water vapor in it, and this is much much more powerful in an engine.
(An offside is a backer for the pattern that avoids asking the foundry to cope down, in cases where it is not practical to make a split pattern. Trivial to model and print, a right nuisance to make from wood). The blue part here: https://photos.app.goo.gl/22AJzREMxDgUW6Dw6 for these lathe steadies: https://photos.app.goo.gl/nv2mer7BrNqfDBp6A
<was expecting an anecdote about superheated steam, battleships and sweeping brushes>
Is there a Steam-boat Hobby Scene? :-D
Most definitely! Steam launches are a big part of the hobby.
Once you have built a sufficiently large steam engine will you convert your machine shop to run off steam powered line shaft?
Welp, time to rewatch "The African Queen"
Steam launches are a popular thing to build because they use simple vertical boilers and simple marine engines which are easy to build, but can still move around.
@mwfeurtado I think Dave Richards over at Steam Powered Machine Shop has that all wrapped up. :D Again, the engine size is less of a factor than the boiler. He has a boiler from an old steam crane that he gets annually inspected and at some point will be at the end of its service life.
There is an example of a marine-style steam engine in Sheffield Industrial museum. It's a three-cylinder one, but not a triple-expansion, it's single expansion and 120 degrees phased. So it can instantly reverse. It was used on a steel rolling mill, but the instant-reverse was also (apparently) useful on ships. My great grandfather actually left the navy to run it.
It's incredible to watch something so huge reverse from full speed in less than one rev.
Just had a quick search, and my goodness, so many steam boats! But yeah I can see the appeal!
Any plans to run something off your engines maybe a small electric generator? Some form of dyno results would be cool to see on your channel for some performance comparison between the various models.
Definitely! I have a number of plans for things to run off these engines. It's a common request. :D An electric generator is on the list for sure. Something like charging an iPhone is easily achievable with these engines. I also drove the raffle drum at a conference with one (video on my channel of that)
@Quinn Dunki You are already 1/3 of the way there to make one of these: (That's the River Don Engine that I mentioned earlier).
(I do rather feel like I am hijacking your chat with all these links, sorry about that, but that link is straight to the best bit) I willl stop now.
A Prony Brake would be a great project as well (a dyno for steam engines, basically. You see these at farm shows where people show off their big traction engines)
What do you burn to power the boiler out of interest?
I have two boilers- one is electric and the other burns camping gas (a mix of propane and butane). "Real" model engineers will scoff because you should be burning coal in a proper model. :D Coal makes a lot more power in the same boiler, but gas is a lot more pleasant and easy to use.
Boilers have to be built in a special way for coal as well. The firebox has to be immersed for safety, you need a way to drop the fire box in an emergency, a fuse plug in the crown sheet, etc. Coal fires can't be shut off, so it pressure gets too high or water gets too low, you have to have other safety mechanisms. Locomotives, for example, can "quick release" the entire fire grate out the bottom of the engine. Rather like ejecting the core on the Enterprise.
interesting, does that mean there's more energy locked away in the coal than gas, or..?
Gas is nice because if something goes wrong, you just shut off the valve. :)
Some of the (full sized) preserved railways are having trouble sourcing the right type of coal. The Welsh pits have shut down, and the other source was the Ukraine.
Yah, the energy density of coal is very impressive. You can burn white hot with it quite easily. The main challenge is getting enough air to feed it!
@Andy Pugh For sure- proper Welsh steam coal is basically gone. Modellers (especially in North America) burn crappy steel-mill coal or other types. Whatever we can get.
i think there is talk of building a new coal mine somewhere in the UK @Andy Pugh iirc
One of the things you learn in this hobby is how many kinds of coal there are. I had no idea ten years ago. I thought coal was coal.
intriguing, so some coal might burn hotter than others?
Very much so.
Yes, traditional Welsh steam coal burns very hot and very cleanly. Makes minimal ash and other crud you don't want in your firebox.
What about oil though?
There are some coals from West Virginia that are pretty good, but not as good. Most North American modelers use WV coal.
I don't think oil burning is very common in hobby steam, probably because of the mess and fumes.
silly question, you couldn't use charcoal?
Theoretically I suppose? Charcoal takes a lot of space and doesn't burn as hot though, so it may not scale down very well. Whatever you burn has to fit in a firebox the size of your hand.
aha, gotcha
You can burn straight wood as well, in larger boilers. Dave Richards (Old Steam Powered Machine Shop on YT) burns regular firewood in his boiler. Not very efficient, but easy. Logging locomotives ran wood for the same reason- it was handy.
Pellet stove fuel maybe?
Interesting... maybe? I've not heard of anyone trying that.
Model engineers tend to very traditional, so they focus on coal (and sneer at the North Americans who run gas)
It is a commonly believed fact[1] that Egyptian mummies (mainly animal mummies) were used to fuel steam trains.
[1] As in I have heard it at least twice, but still doubt the veracity.
In principle anything that will burn can be made to work (mummies not withstanding). It's just a question of how much power it will make, and how much mess it makes in the firebox.
The actively burning parts of a pellet stove _are_ pretty small, as well, might be a reason
Discussions
Become a Hackaday.io Member
Create an account to leave a comment. Already have an account? Log In.