Boiler, build or buy.

I am constructing a stationary factory engine with a cylinder of 1" Dia. x 2" long. I'm undecided whether or not to build or buy a boiler.

Buying is easier and it should come tested, (I'm not a club member so testing is an issue), but will be more expensive...I think.

Pricing up components and materials seems to be cheaper but maybe in the end it could cost more, then there's getting it tested.

What's your experience?

In most places, you only need to get it formally tested and certified if you are planning on running it at a public display such as club days etc where public liability and insurance become an issue. For private use at home you don't need formal test and certificate. You can do your own test using mains water pressure if it's high enough (often up to 80psi or so) or pump it up with a hand pump, and look for leaks. Or use compressed air and soapy water and look for bubbles.

Making your own boiler will definitely be cheaper than buying a professionally made job. A foot-long piece of 3" diameter copper pipe from your local plumbing supplier should provide the shell and the two end caps, made from flattened sections of pipe. If you make your own fittings, also quite cheap. Once you start buying ready made stop valves, gauge glass fittings and safety valve etc, price goes up a bit.

It's not that hard. I made my first one while still in highschool and 45 years later it still works. Didn't even bother with gauge glass or stop valve etc. Just fill it up and run it until it runs out of steam. Its methylated spirits burner is not going to melt silver solder or copper. These days though, it's nice to run a gauge glass etc and use a ceramic gas burner for quicker and easier steaming.

There are several good books around on model boilermaking, and a recent series in ME magazine on making a vertical boiler that might suit your needs that has been discussed on this forum in recent times, all worth a read.

Edited By Hopper on 29/04/2018 05:18:13

I am not sure that pressure testing with air is so good. If you had a catastrophic failure, I would not like to be there. If the boiler under test was sunk in a deep tank of water, then air test, but most of us do not have such tanks - think of a water tank several feet deep. Stick to pressure testing with water only is a safe method.
BobH

I test my air receiver at 20 Bar, or so. Filled with water and then pressurised with a grease gun. Simple and safe.

Hi

The complexity of boiler and thus ease with which it is made varies greatly upon the application of the steam engine being used. If you want your 1" x 2" engine to simply tick over slowly on the bench for a few minutes then a basic pot boiler will work - easy to make yourself and low pressure. If on the other hand you want it to run for twenty minutes whilst powering a boat/dynamo then things become a lot more difficult. Will it stand up to a pressure test of 120 ish psi, is it coal, meths, gas heated, do you need feed water heating, super heating and so on. If it is for your personal use then no official testing is required by law but if you intend to use it in a public place testing and verification will be required. The materials are quite expensive and the fittings even more so. You can buy our boilers with or without fittings and I am always happy to offer advice for free on your boiler build. The hydraulic test is just that (as opposed to a pnuematic test) and this should be used. All commercially built boilers should come with a test certificate stating that the boiler has been tested to 2 x maximum working pressure. Hope this helps.

Nigel

Pendle Steam Boilers

Are you determined to run it on steam? Compressed air is always an option.

I intend to run on steam. Not intending to do public displays but may be asked to show it at local church fund raising events so public liability would be useful. Hope to run it for about 30 minutes max. so need a boiler of suitable size and pressure , this is where I need help. I would probably have a sight glass and filler pump, I've been told that I need two pumps if shown in public.

Coal fired would be nice but not sure how to build one for that. Most times I would use gas. I can hydraulically test myself but that would be no good for insurance.

Joining a club would be ideal but the only one convenient for Doncaster meets on Tuesday nights which clashes with brass band rehearsals, I can't miss those because we play at events where people pay to listen to us!

Just make your own boiler and if you do get asked to display it publicly, plumb a line from a discreetly placed air compressor to the boiler at 10psi or whatever is required to run the engine at a nice tickover. Otherwise, it sounds like you would have to pay for a professionally made boiler . You could probably talk to Fizzy about that, I believe.

Even if you buy a tested one it would need yearly inspection and testing for insurance.

For initial testing to find leaks you could do as I do with the displacers for hot air engines. Stick it in a pot of hot water, if there is a hole bubbles will form, and if you can't completely submerge it, bit of soapy water on the exposed bits will show the leak.

Ian S C

STEPHEN ... one of the replies above from HOPPER, suggests a size of 3 x 12 inches ...a very useful idea, but if you have not built a boiler before, it is quite a hefty size to heat up ... have you any blowlamps to provide that much heat ? and a hearth ? ... what sort of firing do you want ... gas or coal ... what sort of fire tubes or water tubes will you need ... I am assuming there is no local club or model engineering society nearby so there is no-one you can ask ...there have been many books published on building model boilers ... at least in England there have been many ... some by a man called K.N. HARRIS I believe.

the boiler itself plus all its bits and pieces is quite a project ... maybe it would be easier to just run on compressed air ... I will try to find some of the titles if you are interested

martin

Stephen ... have been asking around ... there are 2 books which may be of use ... both by K.N.HARRIS ...one is called Model Boilers and Boilermaking ... the other is Model Stationary and Marine Steam Engines ... I have seen both of these books in the past ... very useful ... I am told that a reprint of each is available from TEE PUBLISHING ... it is in England ... website is www.teepublishing.co .uk

If I was building a boiler for a display I would be hunting round for any other people in New Zealand who are not too far away ... I have noticed various people, all from new Zealand, who all use the M.E. website ... is it a silly idea to see how far apart you all are ?? If you could get together, could you form a club and do your own boiler testing ?? ... or am I living in a dream world ?? my wife says I am.

If the boiler was part of my project I would be looking at a vertical type with lots of vertical fire tubes ... they are very easy to assemble if you use silver-flo 24 first and fasten some of the tubes into one tube-plate ... then pick the OTHER tubes and fasten them into the OTHER tube-plate ... If you have not silver-soldered everything into one solid lump, then these 2 assemblies can be slid into the top and bottom of the shell ... makes final assembly much easier ... just remember to note which tube lined up with which hole !

For all the small boilers I have built over the years, I have always thought the vertical types were just that bit better at raising steam.

martin

martin

Not sure why I give the impression of being in New Zealand, as much as I would like to live there I am in Doncaster. Only one club locally but it meets when I am at band practice. Handy for the Model show though, 15 minute walk from my house!

I have looked on the net for boiler designs without much luck. Maybe looking in the wrong place!

Not sure what size and pressure I will need. I have looked at the books by K.N. Harris, They get a poor review on accuracy but I could cope with that if they are really useful for my needs.

If your local club meets on the wrong day have a work with their secretary about seeing if some members want to meet on other days, perhaps in the pub.

Reeves do the RV series of boilers which are verticals, Sarik Hobbies now sell the old Model Engineer plans and there are a couple of suitable boilers there.

Very good build log of the Reeves RV6 here

Stephen ... my apologies about New Zealand ... I was curious about where you lived and clicked on your profile ... at least that is what I thought I did ... I wonder what key I actually pressed ?? the country of origin was clearly shown as New Zealand ... very sorry.

I am very jealous about your proximity to Doncaster Racecourse ... that is very useful ... as regards size of a vertical boiler I would start with something about 4 inches diameter, possibly 9 or 10 inches high and with lots of 3/8 o.d. fire tubes ... plus a bit for a smokebox on top and a firebox at the base ... unless someone reading this has actually got a design they would share ?

I know that POLLY model engineering do ( or did ) a kit for a vertical boiler, also GLR KENNIONS, also possibly BLACKGATES, possibly REEVES.

martin.

Few suggested sources for plans in this thread here **LINK**

Personally, for running  a little engine under no load demonstration conditions and fired with a gas burner, i would not bother with too much fancy work on firetubes etc. Just make it simple and pour the heat into it with a ceramic gas burner. You don't need a high output boiler for demonstration runs, only for if you are hauling a loco and wagons along a track etc. Unless you just want the challenge of all that silver soldering, which is a world of its own...

Edited By Hopper on 03/05/2018 09:14:23