I'd like to build a simple boiler

[dnp101677]

I've scanned this section pretty well (including Rich's detailed post), but I still don't have a good idea of whether or not I'm getting in over my head. I have a lathe, mill and intermediate skill level, but I've never built a boiler. I just want something simple that I can mount on a plate and power a small steam engine with. I want to be able to take the whole assembly (engine and boiler on a plate) somewhere and not be dependant on compressed air, propane, etc and still be able to power my engine for a short time.

There is so much information out there that I still can't figure out the basics. I mean, what components of the boiler are absolutely necessary and which ones are "Bells and whistles" (no pun intended).

Why is everyone forming copper? Is that just the cheapest way to go because copper is expensive? Or is this a safety thing? Could one use machined pieces and press fits? Does anyone have a set of plans for something simple?

Thank you in advance for your thoughts.

 

[Metal Butcher]

You may want to consider building Elmer's #26 Boiler and engine. It looks like a simple project that would be fun to build!

Elmer's Yahoo group #2 link.

http://groups.yahoo.com/group/Elmers_Engines_2/files/

John-Tom link.

http://www.john-tom.com/ElmersEngines/25_26_WobblerBoiler.pdf

-MB

 

[Metal Butcher]

Here's a link to some more plans that may suit you. I bought a set of these plans a long time ago and forgot all about them! They are very basic plans that will provide a good place to start with building your first boiler powered steam engine.

Have fun, and please post your progress!

http://members.iquest.net/~rwmachine/

-MB

 

[doubletop]

My first boiler was SandyC's 3" vertical the drawings are in the downloads page. My efforts are posted here

http://www.homemodelenginemachinist.com/index.php?topic=8687.0

I see I started the thread on the 13th March after reading Rich's post. That was just one month into this hobby after 44years since metalwork at school. So I'd recommend it as a beginners project, it is simple enough, its safe and there's even the burner in the drawings, so its all there.

Good luck

Pete

 

[Blogwitch]

DNP,

Why is everyone forming copper? Is that just the cheapest way to go because copper is expensive? Or is this a safety thing? Could one use machined pieces and press fits?

Just to answer that for you.

A boiler can be a very dangerous item if not built correctly and of the right materials.

The lads on here respect that fact and actually build their boilers, usually from plans, but if not, using recognised procedures and materials to ensure that their boiler is safe to operate at the pressures they desire.

Everyone on here, I am sure, will give you all the info you require about building a safe boiler, just to make sure that everything turns out with a happy ending for you.

If I can just make one suggestion. What you are contemplating is building what is called a shop test boiler. Most of these are of the vertical variety, mainly because they are easier to make and can easily have different types of burners made and fitted, plus they don't take up as much room as a horizontal boiler on your benchtop.
Something that can generate a continuous maximum of 35 to 40psi would be ideal for those larger engines, and of course, it could run on lower pressures for the small stuff. A boiler of 3.5" to 4" diameter by say 5" to 7" high (excluding burner area) should be about perfect for the job.

I hope this has answered your question.


Bogs

 

[GWRdriver]

Why is everyone forming copper? Is that just the cheapest way to go because copper is expensive? Or is this a safety thing?

To add a bit to what Bogs has just said in answer to your question, . . . it has been determined over time (100+ years) that copper has more desireable qualities and less undesireable qualities for making small boilers than any other metal. Generally speaking the dividing line is 6" in diameter. For various reasons copper lends itself better to model boilers of 6" and below than does steel. Above 6" in diameter, due primarily to cost and availability of copper, the general preference shifts toward welded steel although the dividing point between the two may vary a bit depending upon one's skill, equipment, the boiler design, and material resources.

The reason it's being formed (if that was a seperate question) is because it can be. One of its desireable attributes is malleability which allows it to be formed into shapes that other metals can't as easily be formed into.

 

[dnp101677]

Man, you guys are great! Thanks for the info - I have plenty to read through now and decide if this is what I want to build next or not. I'm kind of leaning towards a hit and miss now as well, but at this point it could just as easily be the boiler and small engine. I guess no matter what a smaller boiler build is in my future; the question is how far in the future is it.

Thanks again for all your comments, knowledge and experience. I really learn a lot from you guys!

Dan

 

[MikeR C]

Actually, I too have wondered why ends are hand made. Pretty much every size copper pipe has a corresponding "pipe cap" to fit. I realize that it fits on the outside of the pipe (boiler shell) instead of inside but it has plenty of overlap and is as thick as the pipe it fits. It would lend itself to riveting and caulking with softsolder as well as silver brazing.
Is it just a matter of cost of the caps?
Pride in "pounding" out your own cap?
I would be interested in knowing...

Thx
MikeR C

 

[shred]

Probably a few things, but #1, end caps like that (long ones) aren't traditional. Another might be it's rather difficult to carefully inspect the solder joint on a capped end. If you shorten the cap down to just a little overlap, they would be more traditional, but pipe caps tend to be larger on the closed end and might not fit as well.

 

[GWRdriver]

Mike,
Ends caps can be useful if what you want to do is build an elementary stationary boiler by enclosing the tube by the most expedient means, consistent with performance and safety. There's nothing wrong with wanting to build an elementary boiler by the most expedient means, but the majority of model boiler builders need to build something more complex which will allow them (and their model) to achieve some level of faithfulness to a prototype or to general industrial practice and end caps almost never get those folks where they want to go. Forming the plates and ends is the only way to do that. The only exception is that if you don't want to do the job, and many don't, formed plates sets are available for almost all the locomotive designs in the UK which call for copper. We have no such service here in the US. End caps are so rarely used they are never mentioned in any of the recognized books and articles on model boiler building.

 

[MikeR C]

Gentlemen,
Thank you very much for the replies. I guess I had in my head one of the boilers with furnaces that mostly cover the boiler shells. I completely understand making the caps so they have a scale appearance as opposed to using the pipe caps. I make all my own nuts and bolts, using standard threadsizes with heads and nuts sized for scale, boring but the finished product is worth it.

Thx again,
MikeR C

 

[Kaleb]

By the way, another good alternative for small, low-pressure boilers is brass welch plugs. I used these on my first engine build, and built a boiler since I am quite a purist when it comes to steam power.

Be sure to put a safety valve on it. I recommend using an off the shelf one. (You can get these from one of the three main toy steam manufacturers: Mamod(UK), Wilesco(Germany) or Jensen(USA).) You can make them, but be sure to test it on your compressor. You should only want about 20-30psi (around 200 kPa) of pressure to accumulate in a boiler like this.

See the thread on my first engine for some hints.

http://www.homemodelenginemachinist.com/index.php?topic=8524.msg90811#msg90811