# Aluminum for steam engine?



## WiKKiDWidgets (Sep 25, 2012)

Curiosity question here regarding crafting a Steam engine entirely from Aluminum. My question is mostly based on two factors. I have prolific amounts of Aluminum in my shop ...but... I have not seen very many (if any) little steam engines made from Aluminum. Is there some prevailing issue with aluminum that makes it an unwise choice? I do have other metals sitting about to craft _other _Steam engines from, but I would sure love to use up some of my aluminum firstly.


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## albertorc19 (Sep 25, 2012)

I use aluminum for structural purposes on small projects, it is great for bases, structural support, etc. I've seen quite a bit of cast aluminum steam  and gas engines on Youtube, try "mrpete222" youtube channel, he has a complete series on how to make a cast aluminum steam engine. There's another channel by "myfordboy" who makes a lot of work with aluminum. I'm not sure if aluminum is the only metal used on those projects but it is certainly used in most of the construction.


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## Neil K (Sep 25, 2012)

There are a lot of "steam" engines made from aluminum that run almost exclusively on air. You'll see them at any model engine show. Some of them are operated occasionally on steam, but need a lubricator as part of the setup. The addition of steam heat to the alumnum will make some of the cold-running fits become too tight to run. You'll have to make some adjustments with the clearances and each engine will be different.

One thing you might consider would be to sleeve the cylinder(s) with cast iron or bronze bushings to help out with the expansion issue and also to give better wear in those areas. The rest of the engine could be fabricated from materials at hand...in your case, aluminum.

There have been many beautifully finished engines made from aluminum - they do shine up really nice!

Neil


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## WiKKiDWidgets (Sep 25, 2012)

@albertorc19 - Thanks for the links. I still have Metal casting on my list of skills to add metal working resume. That is some pretty cool stuff. 

@Neil K - That's more along the lines of the information I was after! I have made widgets of various kinds over the years that had similar functionality to a Piston and Cylinder (Pneumatic type stuff) and had never had an issue with them. The addition of heat from the steam being an issue was the sort of information I was looking for. I knew there had to be a fundamental reason why you don't see more Aluminum Steam engines out there. The bushings make sense to me because I have see that in so many RC nitro motors. Any other considerations to take into account?

Anyone?


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## Ken I (Sep 25, 2012)

Wikki,
Be carefull of using Aluminium and Brass together in "wet" applications - the potential difference between the metals leads to severe corrosion.

If you've ever bought those bling anodised aluminium valve caps and fitted them to your brass tyre valve stem and leave for any length of time, the only way to get them off is to change the valve stem - same problem.

The elbow engine in my avatar uses aluminium cylinders with cast iron pistons - no problems - but I would not dream of using a brass piston there.

FYI the Porche 928 uses an aluminium block and the chromed rings and graphite coated pistons run on the High Silicon aluminium bore - and that motor is considered pretty bullet proof (it does have some patented surface treatment like anodising),

So like a horse - don't put your motor away wet.

Regards,
Ken


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## Jasonb (Sep 25, 2012)

You may also find that an aluminium flywheel is too light unless it is disproportionally large.

Also do you really mean completely out of aluminium as things like shafts, piston rods etc will be better in steel and bearings, glands and so on for those shafts are best made from bronze, fixings again best in steel.

J


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## WiKKiDWidgets (Sep 25, 2012)

@Ken I

Awesome. You have no idea how valuable your input is here. I was very close to making a fatal mistake.  I didn't know about the corrosion issue either. Would it make any difference to the whole concept if I anodized the aluminum?

@Jasonb

Yes, the intent was to make every bit of it out of Aluminum. The reason being is when I say I have prolific amounts of Aluminum, I'm talking several hundred pounds of it lying about. I had the good fortune many years ago to find a young woman who was selling the cutoffs from her husbands Machine shop as her own little side business. I was buying lots at about 1/10th the recycle value. So, needless to say I took advantage of the situation. 

Very good info gents. I so appreciate your input. I would have been devastated if I had gone ahead with making a nice steamer only to end up with a hunk of useless Aluminum.


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## Ken I (Sep 25, 2012)

WiKKiDWidgets said:


> @Ken I
> Would it make any difference to the whole concept if I anodized the aluminum?


 That's always a help but in the case of brass and aluminium it is of little use unless you keep it cleaned and oiled.

Depending on the grade of aluminium it is generally not used for things like shafts & cranks.

Also you cannot run aluminium on aluminium - no matter how well oiled there will be a tendance to gall - running a hard anodised shaft in a "soft" aluminium beariig would probably work but what's the point other than saving on material perhaps.

Great if you have a lot of aluminium and this certainly would prompt me to use it in many places - but I still wouldn't use it as the shaft in running fits.

I think what I'm getting at here is I wouldn't want to put a lot of effort machining some complex part out of an inappropriate material simply to save the material cost.

Ken


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## WiKKiDWidgets (Sep 25, 2012)

More good info. I was familiar with the 'effect' of Galling, but honestly never knew there was a term for it. (Have since read all about it, thank you.) So anodizing isn't going to help much. I guess if I am to use any Aluminum, I will have to but brass bearings and sleeves on any moving parts or only use it for stationary tidbits. Lots of food for thought. Thanks Ken I and company.


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## Tin Falcon (Sep 25, 2012)

As others have said you can make engines of mostly aluminium .
If you have not already done so and I expect you have not read my posts on getting started in model engineering and selecting a first engine to build. 
the second thread talks about material selection some. 
here is a good starter engine. 
http://littlemachineshop.com/Products/Drawings/2593OscillatingEngineAssembly.pdf
as far as aluminum being to light for a fly wheel I have not seen a problem. PMR makes a couple of aluminum kits with aluminum fly wheels. and I have used aluminum for fly wheels on several engines. It is more of an issue if runnning the engine under load. 
tin


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## chipenter (Sep 26, 2012)

I am using aluminum pistons in my steam engine with gun metal cylinders , brass reacts with aluminum becaus of the zink bronze is ok as it has tin ,just need a litle extra clearance for the diferent heat expanshion rates and oil .


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## Ken I (Sep 26, 2012)

Wikki,
        Like Tin said - no reason you "can't" use aluminium for a flywheels - but obviously you are going to need more of it to get the same mass moment of inertia.

Ken


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## lensman57 (Sep 26, 2012)

WiKKiDWidgets said:


> Curiosity question here regarding crafting a Steam engine entirely from Aluminum. My question is mostly based on two factors. I have prolific amounts of Aluminum in my shop ...but... I have not seen very many (if any) little steam engines made from Aluminum. Is there some prevailing issue with aluminum that makes it an unwise choice? I do have other metals sitting about to craft _other _Steam engines from, but I would sure love to use up some of my aluminum firstly.


 
Hi,

As has been said you can make an engine entirely out of aluminium so long as it runs on air , one of the problems with aluminium piston is also the expansion of the stuff with heat, that is something that has to be considered if you are going to use steam ender pressure. I have a small Taig lathe , the aluminium head stock pulley can not be mounted on the spindle unless it is heated, I usually leave it in boiling water for a couple of minutes and then it is a loose fit on the shaft, within seconds it contracts and then is as solid as a rock. that is how much the stuff expands and vice versa.

Regards,

A.G


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## joegib (Sep 26, 2012)

Myfordboy's video series includes one where he:

1. Machines a circular trough in the rim of the aluminium flywheel he's cast, and 
2. Encloses the rim using a large jubilee clip through which an entry hole has been drilled, and then
3. Pours molten lead into the all-round cavity to provide weight.

He then goes on to roll a heavy steel ring to form the outer rim and add further weight. Latter might not be practicable if you haven't got bending rolls but you could always finish-turn the flywheel's ally/lead surface and paint the wheel.

The video is here:

[ame]http://www.youtube.com/watch?v=m_-iPpEuWRA[/ame]

Joe


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## Charles Lamont (Sep 26, 2012)

Aluminium alloys are pretty good conductors of heat - good for cooling an internal combustion engine, but with a steam engine cylinder you want to keep the heat in. On the other hand, if it is actually to run on air, and you want it to run expansively, then a finned alloy barrel would help to get ambient heat in!

As a rough summary of the preceding comments, by all means use alloy for the bits that don't move, but mostly there is a good reason to use something else for moving parts. Alloy con-rods might be good, though. 

If I were going to use alloy for a sliding surface (like the cylinder bore) I would want to try to get it hard-anodised.


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## WiKKiDWidgets (Sep 27, 2012)

Many thanks gentlemen. That is some great information. Gives me a lot to ponder. It was curious that Tin Falcon mentioned the PM Research engine. I said to myself, '_Hey, I have one of those!_' (I adore garage sale finds.) I nabbed that off the shelf and took it apart. Cast Aluminum Cylinder with a Brass piston. I have enough info here to feel comfortable experimenting. 

Thank you for sharing your knowledge.


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## larrymaden (Jun 4, 2013)

Tin Falcon is absolutely right, aluminum can serve perfectly effectively as flywheel material, in many cases, especially in low-torque model, aeronautical, or any application where the drive is thru some fluid or magnetic coupling or any other 'soft' power transfer method.
There is a lot of uninformed opinion, here, or just plain ignorance of metallurgical properties, and the actual torque requirements involved. You are all model engine makers, for Pete's sake! You never actually put your engines under any real significant loads! Of course, one could make an almost entirely aluminum model engine, just use teflon bushings on the shafts. Corrosion can and will happen to some extent between any two dissimilar metals, even worse if there is any source of electron flow, nearby. Even highly polished ferrous metals cannot run on aluminum bearing surfaces without constant forced lubrication, hence the very cheap and successful camshaft running directly on an aluminum head of most modern OHV IC engines. The worst problem with the use of dissimilar metallic bushings is the lower coefficient of linear expansion of nearly all other metals compared to any aluminum block. Thus, the hotter the engine gets the more the bushings loosen up in the their bores, until they can spin, negate any value to having the bushing there. So, if you use ferrous shafts, either, provide constant pressure oiling on aluminum bores, or, again, teflon bushings (other high-lubricity polymers can be used, but teflon is the best choice for steam, up to 500 degrees Fahrenheit). If you insist on using dissimilar metal bushings in aluminum, you must double the interference of the fit, over that which you would use for a ferrous metal bore. Then, you will ruin the aluminum bore, when pressing it in, unless you heat the aluminum block and cool the bushing, before you put them together with silicone or teflon lubricant on the bushing to keep the heat transfer slow enough to permit you time to press it to the bottom of the hole. We have only had success installing such bushings, dry, in unheated aluminum, by using liquid nitrogen to cool the bushing. Then, you can just drop it in the hole, stand back, and listen to it scream as it grows to tighten, permanently, into the bore! Teflon bushings really are the best solution, as any engine, for practical use in any modern auto or loco-motive application, usually needs a sealed crankcase, anyway. Teflon serves both purposes. Yes, we can make practical use of steam engines, today, with the modern metallurgical technologies that they lacked in the "Golden Age of Steam". They are not just toys, or obsolete technology of yesteryear, but the ultimate flex-fuel automotive engine of the future, and they will be made almost entirely out of aluminum, except for shafts, pins and fasteners.


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## Septic (Jun 4, 2013)

Even Regular, home anodising of aluminium surfaces where friction occurs will alleviate many potential problems, although "hard" anodising of alloys such as T6 (properly heat treated of course) will give you a vast improvement in dimensional rigidity, strength and abrasion resistance.


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