# Material for steam cylinders?



## Amber (Jul 29, 2011)

Just a question, would brass be a good material for the cylinders for a steam engine? I'm wondering, because the brass pipe pieces that can be bought at the hardware store are pretty smooth on the inside. I was looking at stuff at the hardware store today and found that the 1/2 inch brass pipe is actually pretty close to 5/8ths inch inside, you can put a 5/8ths bolt in the pipe with a nice snug fit. So, if the piston were made from a piece of 5/8ths rod or a section of a bolt, that would be easier to build than having to machine all the parts from stock.
So, opinions on that idea?


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## Amber (Jul 29, 2011)

One other thing that I forgot, would the bronze bushings from the hardware store be usable for cylinders? They're not real smooth inside, but probably could be polished up a bit.


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## HMeinhold (Jan 2, 2008)

Both brass tubing and bronze bushings (McMaster carries bronze bushings with a smooth bore) can be used for steam cylinders. However this only works if you assemble the cylinders with screws/gaskets and/or soft solder. Silver brazing distorts them and they need to be reamed. Contrary to boilers cylinders can be soft soldered, unless you use superheated steam.

Regards


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## Amber (Jul 29, 2011)

I was thinking about using the threaded brass pipe pieces for the cylinders. My idea was to cut the piece to length and then solder a flange on each end that the end caps could be screwed down to. I found a metric flat washer that fits over the outside of the pipe snugly, the washers are fairly thick, but the outer diameter is not way bigger than the inner diameter, so I shouldn't have to file down the outer diameter to have them look ok. I figured that I could solder a washer on each end of the pipeand that would work for the flanges. The slide valve assembly probably won't be so easy, but I have plans for a couple of different small steam engines, so I should be able to figure out something to use.


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## Eric M. (Jan 3, 2008)

Amber, just make sure that they are hard bronze and NOT sintered bronze.

Regards,

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## Amber (Jul 29, 2011)

Eric, I was wondering about that. I think the bushings that the hardware store sells are sintered bronze, probably better for holding oil in the bearing that way. I'll try the brass pipe pieces and see how that works out. Can neoprene "O" rings be used for a piston ring, or would something else be better? I can't do any precision machining, I don't have the equipment, so I'm trying to come up with solutions that don't require machining. I have a drill press and a band saw.


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## Phippsburg Eric (Jan 10, 2008)

Certainly "O"-rings can be used as piston rings, however there are several types of "rubber" used to make them. I do not think Neoprene is the right kind, here is a listing of different materials that O-rings are made from the best being PTFE or FEP. you will need to do more research to find out what these materials are. 
http://www.mcmaster.com/?orderview=new#o-rings/=gjoyq3 (click the "general Properties of O-rings materials" at the top of the page)
you can order O-rings from this company too, though only in bag lots which is probably a lifetime supply.


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## Amber (Jul 29, 2011)

I'll have to check those out on my next visit to the hardware store, maybe I can find something in the plumbing section.


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## Ray Cadd (Dec 30, 2008)

Amber, not sure of the particulars of your project, but you might be able to use graphite string packing for rings. I've used it in my Ruby #5, to replace the neoprene factory rings that didn't work. The Brits have used it in small scale models going way back to the LBSC days and more. You have to unwind it into fine threads, then roll it into the groove using a surface plate, glass sheet or any decent flat surface. Cheap and easy to find, and fits many sizes!


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## Phippsburg Eric (Jan 10, 2008)

Graphite string can be made using cotton string which has been unwound and fluffed up the saturated in steam oil mixed with graphite power ( sold as a lubricant for locks ) I havnt used it as a piston rod but have used it as a packing for the gland nut where the piston rod exits the cylinder. works great and is cheap and easy. 

Amber-- I am not sure you will find these unusual material O-rings at your local hardware store, They will certainly have the kind that work with home water systems and maybe hydraulic equipment. I looked it up...one of the best materials is PTFE which is Teflon which is not a common household O-ring material.


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## xo18thfa (Jan 2, 2008)

Brass pipe will work fine. I've used bronze bearing for cylinders too. They work. The first engine I ever built had a cylinder from K&S brass tube. It works too. If you use pipe or bearing, spin some steel wool inside just to knock down the shine a bit. Oil does a better job of lubricating with the shine rubbed off.

As Henner said, soft solder the cylinder assembly of you use tube, pipe or bearing. Soft solder works perfectly fine for cylinder assembly. They don't get hot enough to bother the solder.


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## HMeinhold (Jan 2, 2008)

All my locos have now Viton O-rings. It is softer than PTFE and seals/glides well. McMaster carries them.

Regards


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## xo18thfa (Jan 2, 2008)

Posted By HMeinhold on 06 Mar 2012 07:29 PM 
All my locos have now Viton O-rings. It is softer than PTFE and seals/glides well. McMaster carries them.

Regards


Second that.


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## Amber (Jul 29, 2011)

I wonder if viton O rings could be found at the car parts store?


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## steveciambrone (Jan 2, 2008)

Ordering online from McMaster Carr is easy and the shipping is reasonable, considering the gas and time spent driving to find the odd things needed for the hobby. 

Steve


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## Phippsburg Eric (Jan 10, 2008)

Henner-- 

I see Viton as listed as not reccomended for steam though it takes the temperature OK Obviouly you have had good success with it. Do you know if that is the same material used by Roundhouse Engineering? 

Amber-- I have made several small oscillating engines using K&S brass tubing. I have used the telescoping properties of the tubes to advantage...one tube for the cylinder one for the piston. the simplest is a single acting engine where the bottom of the cylinder is open, and the piston is solid at the top and connects to the crank at the bottom.Here is an early engine I built for a little tug boat. I built this as a teenager with out the use of a lathe or drill press.






























This engine runs pretty well and is powerful enough to move a 20" tugboat. It is not as good as a precision machined engine but it works! 










This engine is quite a bit more sophisticated. I did need the use of a lathe for a little while for the pistons, lower cylinder heads and fly wheel. the rest was built from K&S brass stock by hand. this engine pushes along a 30 " tugboat smartly. With this type of engine the piston can get hot enough to melt the solder where it connects to the piston rod. It should be threaded, though locktite might work. this little engine saw quite a bit of use over the years until I found a small Saito engine to replace it with.


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## Dwight Ennis (Jan 2, 2008)

Photo tip - always insert a space or two after each inline photo.


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## Amber (Jul 29, 2011)

Really neat little engines!


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## rkapuaala (Jan 3, 2008)

Eric, those are very cool.


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## HMeinhold (Jan 2, 2008)

Eric,
I think Roundhouse uses silicone rubber rings. We found, that Viton is a good compromise between temperature resistance, softness, chemical resistance (steam oil) and friction. So far the O-rings in my Betsy have been in use for several years now. I had buna rings (the only choice they had at the hardware store) in my Guinness, but they were chewed up after a few steam ups. The Viton rings are still OK after about one year. But to be honest, I am not sure if other materials may be better. The Teflon rings I found at work were way too stiff.

Regards


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## Michael Glavin (Jan 2, 2009)

Viton has proven to be very durable in my experience with steam powered and heated equipment and it’s impervious to most solvents too. Over the years I have been specifying Viton in lieu of Buna, Neoprene and Nitrile simply because its holds up much longer than the aforementioned products. I commonly use Viton with pneumatic/steam powered cylinders (piston & shaft seals), push-lok air fittings, shaft and lip seals, gaskets, O-rings, flexible couplings and hoses of various forms. In my work we use boilers operating between 85 &t 150 psi together with aggressive solvents, the temperatures generated herein and solvents rage war on rubber comprised products and or components. Teflon or PTFE is commonly used in my industry; primarily for gaskets, flat bearing/slide applications and piston/seals of various sorts.

On a regular basis we cut our own Viton gaskets and or request same of our local rubber suppliers. In sheet form Viton is easy to work with. 

FWIW:
Viton is moderately expensive in most forms compared to other rubber type products; less O-rings. 
Viton products are readily available here locally in Sacramento, CA from rubber & hose product dealers/resellers.

Michael


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## abby (Jan 9, 2008)

Try the "quadra lip" type of Viton ring , I use them in my cylinders and find them better than conventional round section as they seem a little more size tolerant. The difference of a couple of thou in the ring groove depth can make quite a difference to the amount of friction on the ring. 
Getting a non stick-start fit can be tricky for a beginner , and the fitting spec sheets are usually for high pressure systems. 
My spec sheets recommends Viton for steam applications , and silicone rubbers are specifically not-recommended , and have a higher co-efficient of friction than Viton too , so I would be suprised if Roundhouse use them.


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## Amber (Jul 29, 2011)

I was hoping to get something locally, but it looks like I'll just have to order the O rings. 
Now I have to figure out how to attach the steam chest to the cylinder. I'm using a piece of brass pipe for the cylinder, so I should be able to file a small flat area on the pipe for the base of the steam chest without affecting the strength of the pipe. Then I'll just have to build it up from there. I wonder if brass on brass will be a wear problem for the slide valve, or if I should use something else for the slide valve.


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## Phippsburg Eric (Jan 10, 2008)

If you get brass pipe, the walls are thick enough that you can file a flat spot ...as long as you dont get carried away. you may not have much stock left in the cylinder walls for threaded fastenings but solder will work if carefully done. 

If kept well oiled a brass on brass slide valve will work fine. certainly it will wear more than mixing brass and say cast iron. but most of our commercial models are brass or bronze.


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## Amber (Jul 29, 2011)

My plan is to solder a washer on each end of the brass pipe for a flange to fasten the end caps to. They'll stick out a bit, but I'll have plenty of space to drill the holes for the end cap screws. That should also give me plenty of space to attach the cylinder to what ever frame I decide to make. I found a metric washer that will fit on the ends of the pipe with just a little file work on the end of the pipe, it fits most of the way over the pipe threads as it is. for the one end, I just have to file down the threads a bit until it fits, and then cut the rest of the threads off. The other end will take just a bit more work, the pipe I bought is long enough to make 2 cylinders with. Then I have to make the steam chest and slide valve, that should be "interesting" with just a drill press, but I have a set of plans from an old book reprint that shows how to do that.


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## Eric M. (Jan 3, 2008)

I believe Eric is talking about filing the flat on one side of the cylinder wall for attaching the valve chest. This is why it is easiest to have some material with sufficient wall thickness to machine a flat AND drill and tap to fasten the chest or solder it. to the cylinder body.

Any reason for the aversion to ordering materials? I like the adventurous DIY spirit but life would be easier for you if you took a peek at McMaster.com. They have all sorts of pipe, tube, bronze sleeves, etc. for your fabrication pleasure. In the long run it might save you some grief to start with the right materials. On the other hand there is part of me that wants you to proceed with the route you are on because if you manage to build a working steam engine using only Home Depot materials that would be an impressive achievement indeed...

Regards,


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## steamboatmodel (Jan 2, 2008)

I will quote from another forum about Viton O rings; 
"All that derek says is true, and that might incline people to use Viton O rings. 
They have 2 issues that might make them less than ideal: 
1) If overheated (405 degC) they release Fluorine gas, which immediately dissolves in atmospheric water to form HF hydrofluoric acid - this destroys metals, glasses and people and is hazardous even in o ring quantities 
2) Viton is physically weak by elastomer standards 
3) its VERY expensive (but that may not be a problem) 

Nitrile will probably be fine - the 100 degrees is the PERMANENT temperature it will stand to work 24/7 with no loss of elasticity or other properties. We don't mind replacing a o ring each year. Nitrile is hopeless in air (ozone) and especially ozone but both of these are limited in a steam engine 

My strong preference would be silicone, where the temperature is immaterial (I use it in CO2 motors at minus 20 or so). It can be made hard enough to reduce friction (about 75 to 80 shore A if interested) and the oils used will just make it swell temporarily 

hope this is helpful, 
I have probably given the impression that viton has its problems - I don't use it . Leave it for aerospace where it is essential, and the maintenance chaps know its habits" 
I did Hydraulic and Pneumatic work at one time and there was one fellow in the shop who had lost some fingers from Viton. 
Regards, 
Gerald.


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## HMeinhold (Jan 2, 2008)

Posted By steamboatmodel on 09 Mar 2012 10:48 AM 
I will quote from another forum about Viton O rings; 
"All that derek says is true, and that might incline people to use Viton O rings. 
They have 2 issues that might make them less than ideal: 
1) If overheated (405 degC) they release Fluorine gas, which immediately dissolves in atmospheric water to form HF hydrofluoric acid - this destroys metals, glasses and people and is hazardous even in o ring quantities 
2) Viton is physically weak by elastomer standards 
3) its VERY expensive (but that may not be a problem) 

Nitrile will probably be fine - the 100 degrees is the PERMANENT temperature it will stand to work 24/7 with no loss of elasticity or other properties. We don't mind replacing a o ring each year. Nitrile is hopeless in air (ozone) and especially ozone but both of these are limited in a steam engine 

My strong preference would be silicone, where the temperature is immaterial (I use it in CO2 motors at minus 20 or so). It can be made hard enough to reduce friction (about 75 to 80 shore A if interested) and the oils used will just make it swell temporarily 

hope this is helpful, 
I have probably given the impression that viton has its problems - I don't use it . Leave it for aerospace where it is essential, and the maintenance chaps know its habits" 
I did Hydraulic and Pneumatic work at one time and there was one fellow in the shop who had lost some fingers from Viton. 
Regards, 
Gerald. 
Gerald,
I agree with 1), but with saturated steam in a cylinder you never get such a high temperature. If a Viton O-ring looks kind of charred, do not touch it with your bare hands (We use Viton extensively at work).2) I have never had a Viton O-ring rupture, even when peeling it over the end of a piston, so it may be strong enough for our purposes. 3) Now you may have mixed it up with something like Kalrez. Viton O-rings are dirt cheap. Even McMaster sells them for about $4.50 per 100 for e.g. size 008. I don't think a nickel/O-ring will break the bank







. I tried silicone and was not happy with it. I think the slight swelling due to the oil caused friction. 
Regards


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## Phippsburg Eric (Jan 10, 2008)

Amber-- 

If you have limited funds or limited skills, start with simple projects that use basic off-the-shelf stock (K&S or brass pipe) Play with the stuff and have some fun. Don't try to build a Challenger right out of the gate though! Start with something like the BARGS project engine in what ever scale. you may need to try a couple of times to get any given part right the first time, this is natural and part of the fun. 

I have certainly learned a lot using K&S brass tubing to build engines and I have worked on a small walking beam paddle boat engine using Red Brass pipe but since I have purchased a lathe, and small mill, I have tended more toward solid brass stock as a more satisfying starting point for my projects. 

I will have to agree with Eric M that you will probably have more fun using proper materials if you can afford them and have the tools to work with them.


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## Amber (Jul 29, 2011)

Eric S, where's your sense of adventure?  
Seriously though, one of the reasons that I'm using local materials is that I don't really know what I'm looking for, so by using locally found materials, I can handle the parts and try different combinations to see how things might fit together. I can visualize an assembly much better if I have parts in my hand rather than looking at pictures on the computer. Once I know what I actually need, such as the size of an O ring, then I can order the right size parts. Even the small hobby size lathe is well beyond my financial means right now, so I have to be more creative in my materials. Also, there is the challenge of building something like this using the most basic materials, just to see if it will work. I will admit, it would be nice to be able to turn down a piston that actually fits properly in the bore of the cylinder, but I'll do what I can with what I have available. Who knows, it might even work!


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## xo18thfa (Jan 2, 2008)

Posted By Phippsburg Eric on 09 Mar 2012 02:06 PM 
Amber-- 

If you have limited funds or limited skills, start with simple projects that use basic off-the-shelf stock (K&S or brass pipe) Play with the stuff and have some fun. Don't try to build a Challenger right out of the gate though! Start with something like the BARGS project engine in what ever scale. you may need to try a couple of times to get any given part right the first time, this is natural and part of the fun. 

I have certainly learned a lot using K&S brass tubing to build engines and I have worked on a small walking beam paddle boat engine using Red Brass pipe but since I have purchased a lathe, and small mill, I have tended more toward solid brass stock as a more satisfying starting point for my projects. 

I will have to agree with Eric M that you will probably have more fun using proper materials if you can afford them and have the tools to work with them. 


I agree. Start simple. K&S telescoping tubing is just right for cylinders and pistons. They provide a good close fit. K&S has all the brass shapes you need. My first engine (all K&S) had a real jazzy flywheel -- a faucet handle.


O-rings are the way to go of course, but they require a fair amount of machining practice to fit right.


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## Amber (Jul 29, 2011)

A faucet handle! Hey, I hadn't thought of that!  
I have a fair amount of the different size K&S tubing, a lot of it telescoping, from other older projects. I could use some of that for an engine I suppose. I can see that it would work. That tubing would probably also be good for various bushings for pivot pins and things like that.


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## xo18thfa (Jan 2, 2008)

That engine ran a little boat I built. The boiler was a modified soft soldered aerosol can. Alcohol fire. I would turn it loose on the lake then swim out to get it. Ran great until some prick ******* ran over it with his hydro plane. Now it rests at the bottom of Lake Minnetonka, all hands lost.


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## Amber (Jul 29, 2011)

I managed to get some work done on the cylinders today. I'm using 1/4 inch brass plumbing pipe pieces for the cylinders, interestingly enough, they measure out to 3/8ths of an inch inside diameter. I have a piece of K&S brass tubing that is a nice snug fit in the pipe, and the unthreaded part of a 3/8ths bolt fits pretty snugly inside the pipe also. I'm going to try making a piston from a short section of the bolt, if that doesn't work, I'll try the K&S tubing. I cut the cylinders 1-1/4 inches long, to make sure I have enough length. I'll try to build a crank with about 3/4s of an inch of throw for the piston, 3/8ths each way from center. I still have to piece together the steam chests for the cylinders, that will be interesting. 
The next set of cylinders I make will be bigger than these, these just seem small to me. They'll probably be fine for a G gauge chain or gear drive engine.


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