Author Topic: Small boiler build  (Read 10060 times)

Offline lakc

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Small boiler build
« on: May 29, 2014, 04:14:39 AM »
 As it so happens, at NAMES in 2013 I bought a PMR #5 engine for the oldest grandson, and as therapy for me as a break from designing my own works. I made rather quick work of that project. and learned quite a bit along the way, but as it was poorly documented on my part, I never offered up a build log.

 Around the July 4th holiday I was starting to actively search my own meager stockpiles of red metals and reading up on various boiler builds and trying to commit Harris's book to memory. While drooling over so many beautiful works of art as various locomotive boilers and several lovely vertical boilers, I looked into my rather empty wallet and sadly realized a piece of 4" or 6" diameter copper pipe of the appropriate thickness and appropriate tube and plate would equal more then a mortgage payment. If I wanted a boiler I would have to do with what was available to me, or affordable with the spare change I find in the couch every week or so.  :wallbang:

 I have always enjoyed metalworking, and coppersmithing is an excuse to work with the most compliant metal there is. About the only useful things I had on hand were a package of copper rivets and some small size copper water pipe. A few questions in a couple of forums, and a bit of cross referencing specs across both oceans confirmed this pipe was at least the correct alloy to use for a boiler.

 Armed with the proper math, I wrote up an excel spreadsheet and started playing with the numbers. The smaller the diameter the boiler, the thinner the copper could be. I couldnt make a 4" boiler like I had originally wanted, I couldnt even make a 2" one, but just a little over 1.5" would be possible. The numbers worked out, it was safe, and I had nothing to loose. Well, almost nothing to loose, as I watched my last $70 fly out of my pocket for a single ounce of 45% silver solder. :facepalm2:

 Having read probably every boiler build thread on several forums by no means makes me an expert, but watching some posters get excoriated for some homebrew designs (most of them rightfully so) has made me quite leery of posting this. I have done quite a lot of research into this, boilers of any size can be disasters in the making. I built this knowing me and my loved ones would be in close proximity to it at working pressures. I am aware as I believe anyone can be on things like hoop stress, creep, hot strength, and hydrogen embrittlement. I am not going to offer this up as a design, I don't want anyone else to try to build it.  I wont mention any specifications, sizes, pressures, etc. This is my first boiler. I have already learned enough along the way to say I wouldn't duplicate this effort again, but the experience has been invaluable. I present this so you can follow along in this journey, and at the very least have something quite different to view for a change.

 Tomorrow, I will start posting some pictures, and building the story up to where I am today. I was a bit too long winded and ran out of evening over here. :(
Jeff

Offline DavidF

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Re: Small boiler build
« Reply #1 on: May 29, 2014, 04:37:28 AM »
LOL  well my first boiler was made from a couple old propane tanks with a bit of exhaust pipe passing thru it. Fueled by 3 sterno cans and operated at 150 psi!!  :ShakeHead:  I know better now... Im thinking a forced circulation boiler like a lamont would be intersting to build...

Offline lakc

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Re: Small boiler build
« Reply #2 on: May 29, 2014, 11:05:42 AM »
Ok, sorry for the delay, on with the show.
As this started out as a bit of an experiment, the very beginnings are not well documented. We started with a few tubes cut lengthwise with a pair of hand shears and hammered-annealed repeatedly until we came up with two half rounds for the main shell. These were single butt joined with a couple of rivets to hold everything in place for soldering. A radius was turned on a piece of round steel for a former and the two end plates were formed with a hammer over the former. Copper is a magnificent metal to work with as long as you pay attention to its work hardening and anneal it often. Shrinking metal, making the lips thicker by hammering the metal back into itself, is probably the most fun you can have with a hammer. :)
Sorry for the lack of pictures up until this point but here is where we begin.

Jeff

Offline lakc

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Re: Small boiler build
« Reply #3 on: May 29, 2014, 11:12:10 AM »
Next we needed two parallel tubes exiting the shell. Two holes were bored in a piece of scrap steel to hold the parts and two holes carefully made in the shell to receive the tubes.



Soldering at these sizes was easily accomplished with a MAP torch.
Jeff

Offline lakc

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Re: Small boiler build
« Reply #4 on: May 29, 2014, 11:19:56 AM »
Now that we had the tubes, we needed something to stick on the end of them. Holes were carefully made in two tee's for the water tubes.


And then some endcaps for the tee's were made and soldered into place, loosely fit together in this next picture we see it taking shape.

Ill leave this right here for now, have to go to work to make the change that some bits fall into the couch that I can find to buy more tools and make more fiddly bits. 8)
Jeff

Offline Dan Rowe

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Re: Small boiler build
« Reply #5 on: May 29, 2014, 01:04:25 PM »
Nice Jeff,
A sectional header water tube boiler shades of Babcock & Wilcox.

Dan
ShaylocoDan

Offline Alan Haisley

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Re: Small boiler build
« Reply #6 on: May 29, 2014, 06:26:21 PM »
 :lolb: Never would have thought of using coffee as flux like that   :ROFL: :ROFL: :ROFL:
Alan

Offline Maryak

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Re: Small boiler build
« Reply #7 on: May 29, 2014, 10:00:27 PM »
Nice Jeff,
A sectional header water tube boiler shades of Babcock & Wilcox.

Dan

B&W Sinuous Header, horrible bloody things, all those square handhold doors in the headers each with 4 tubes behind it. I once blacked out the whole of Potts Point and Kings Cross in Sydney when I lost my forced draught. I also lost several yards of skin after the chief had finished with me.

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline lakc

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Re: Small boiler build
« Reply #8 on: May 29, 2014, 11:03:30 PM »
Thanks for the comments guys, lets get back to the fun.
After a very long winter I picked up a few goodies from PMR at the 2014 NAMES show. I settled on one small boiler bushing for the feed water at the bottom, and one large one at the top  for a manifold for steam and gauges. Having weighed a few different ideas for stays, I ended up just soldering a thick block of copper to the inside of the cap, allowing me to tap each end for the sight glass. A vertical sight glass that short would be useless, so I will make a diagonal one parallel to the main drum.


Jeff

Offline lakc

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Re: Small boiler build
« Reply #9 on: May 29, 2014, 11:09:14 PM »
Now comes the next part, soldering the end caps.






That sure looks pretty coming out of the pickle bath.
Jeff

Offline Robert Hornby

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Re: Small boiler build
« Reply #10 on: May 30, 2014, 01:41:12 AM »
Coming along nicely Jeff, great photos too. :cheers:
Robert
Age and treachery will always overcome youth and skill

Offline lakc

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Re: Small boiler build
« Reply #11 on: May 31, 2014, 04:35:15 AM »
 Thanks Robert.
 Busy busy day today, not much of it spent on the boiler but I am surprised I managed to get done what I did. Still trying to catch up with the present day so here are some more pics.
With the endcaps all soldered in place it was time to get down to business with the water tubes.



 Not a very pretty job I admit, there were some obvious gaps and it took three attempts to get them all filled. I made up some plugs which leaked slightly but was able to pressurize it  with breath and hold it under water to check for bubbles. I put the camera down for the rest of the day because it took 8 more attempts at fixing leaks before I declared it ready for hydro testing. Constantly checking for bubbles, resolder, pickle, check for bubbles ad nauseum. I wasnt too disappointed as it was my first boiler and first success at silver soldering. As the last light of day faded away it finally passed the final bubble test.  :cheers: So then began with great haste the build of the PMR boiler feed pump that was under my bench for the past year. Pretty straight forward build that involved plenty of cranking the table up and down to get proper drill depths, as I dont have a readout for my quill feed and it gets very tiresome counting threads on the quill stop. I do have a DRO on the knee axis and that worked splendidly.Not much to show for a simple job like that so I will just leave a pic of the temp setup for hydro testing.

Jeff

Offline lakc

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Re: Small boiler build
« Reply #12 on: June 02, 2014, 02:32:57 AM »
 Pressure testing was uneventful for the boilers point of view, still rather scary for me. Having never done one before, I realized I didnt have a good gauge to use. Finally settled on my old A/C gauges, as the high side gauge reading would be right in the center of travel. Initially, it bled down a lot, which was scary until I realized the pump would bleed back over 80 psi. A gentle tap to seat the checkball fixed that problem. Once the air is bled out I didnt think of how fast the pressure would rise for such a small boiler, and accidentally over pressurized it to 300 psi. It made me proud, however, as not a tink or pop came out of it the whole time.


 Now that it tested good, it feels like the job is not even half done.  >:(

 Looking at all the B&W sectional views I have, mounting this thing would require quite a bit of fancy brickwork, and is still kind of a "try as you go type of operation". The heated gas path needs to make a Horizontal S back across the tubes and out the back. Here are a few shots of the idea progression.



 The brickwork surrounding it is roughed out here. Then I changed my mind to a brass box surrounding it, then decided to have bricks on both sides of the brass box. The steel plate will hold the assembly, the cast iron pipe fitting is drilled and tapped 4-40 and will only serve as a base for the 3/4 pipe chimney. I dont expect any useable draft out of this scale so its pure guesswork here.











 The steam dome was a hammer job I decided not to use as a soldered part, but it might be useful for hiding some of the fittings eventually.
« Last Edit: June 02, 2014, 02:36:59 AM by lakc »
Jeff

Offline lakc

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Re: Small boiler build
« Reply #13 on: June 05, 2014, 02:42:51 AM »
 Catching us up to modern times. :) I hoped this boiler would be a steam plant to use on several small steam engines. I have 4 grandchildren and eventually will build one for each of them. Keeping that in mind I wanted the steam plant to be modular, so that it could sit in the middle of 4 separate engines. Part of my idea was to hide the pump as much as possible, so here is what I came up with.

 Thats "kantkink" steel brake line for the boiler feedwater. I keep it in stock so had plenty, it conducts less heat which is both good and bad, but its very easy to work with. It doubles back around underneath the boiler before exiting to the pump.

 Once I mounted the pump I took everything over to the surface plate to measure the hole to cut for the reservoir, and a slot for the pump handle. Keeping in mind the brickwork will have to fit around everything on the surface.

 Here it all is, roughly in place. Finally getting an idea of how to finish it off. You can barely see it in the picture, but I slotted the chimney pipe side for the exhaust to exit. Getting any draft out of this setup is likely the biggest challenge coming up. It might be time for a tiny steam turbine as a draft fan.

 Here is a shot from the bottom of the interior brickwork looking up. The brass deflector is almost edge on and sort of hard to see. I may have to clearance the brickwork a bit more, but forcing the air to travel this path would probably take a scale 100 foot chimney.

 Now your all up to date, next will be some type of burner and more brick and sheet metal work to close it all off.
Jeff

Offline lakc

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Re: Small boiler build
« Reply #14 on: June 08, 2014, 05:16:24 PM »
 Moving along. :) Having tried to drill and tap the pipe fittings without the proper fixture, I relented and made one up.

 If you look closely, you can see where I really screwed up.  :censored:

 It seems, I was using the wrong tap the whole time, 1/4-32 instead of 1/4-40. Lesson learned, dont trust your eyes, and try not to buy any more taps with blurry inked identification stamps instead of engraved ones. I drove this lesson home by having to single point thread a bunch of pipes! On my lathe, this is best done by rotating the headstock pulley by hand. So I got a real workout, and a ton of threading practice, all to teach me to pay more attention from now on.

 Of a boiler this small in diameter, I needed a long sloping sight glass because there was no way to make a vertical one of any use. I ordered some 510 bronze to make the right angle adaptors. Having never worked with this material before I was in for a surprise. This is some really tough stuff.

 It bent my thin homemade A2 parting blade! Here it is snugged up to index the cross drill operation.

 Everything went more or less to plan, so here I am happy to have plugged a couple of more holes.


 One final note on the burner, I have no idea how well it will work but drilled some #70 holes in some pipe and will try propane. I figured I had to start somewhere.  :thinking: You can even see one of my bastard sized pipe adapters in this pic.

 
Jeff

 

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