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Post by modeng2000 on Jan 26, 2008 12:14:15 GMT
I am looking for a vertical boiler for my gauge 1 De Winton style loco and have found on the web these three designs:- Dave Watkins's Idris; Otto Hadorn's Climax www.gartenbahn.de/climax/bauprojekt.htm and this one from Pierre Duval jpduval.free.fr/ARV_DL_45/Plans_ens_A3_ARV_DL_45.pdf I expect they all have their merits but I'm a bit concerned by Otto's as it uses brass in its construction and so perhaps the design ideas might be OK if I use copper. Are there any vertical boiler designs that might be better for me to use? John
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Post by havoc on Jan 26, 2008 16:44:18 GMT
Don't see any problem in using copper instead of brass. The Duval boiler is rather large. I have taken a good look at it because I liked his autorail, but that boiler is almost the size for a 3.5" engine.
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Post by modeng2000 on Jan 26, 2008 17:18:46 GMT
Havoc, yes the Duval boiler is rather large but I wondered if the design was right I might scale it down to suit my loco. It looks like some thought has gone into it's design so it is a bit more complicated than the one by Otto Hadorn.
John
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Post by havoc on Jan 26, 2008 19:21:49 GMT
I fear that if you scale it down then the curved boiling pipes will become a bit too small in diameter to be efficient, or they are so large they obstruct gas flow.
I cannot remember the Idris boiler right now, it is on the other pc that is under maintenance.
How do your cilinders compare to those used with the other boilers? It all boils down to heating surface. (bad pun, I know) There is no need to make the boiler larger than needed, you wil only blow the safety and a too small boiler will struggle when the weather isn't right.
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Post by modeng2000 on Jan 26, 2008 20:06:27 GMT
The Idris boiler has porcupine quills instead of the boiling pipes and is used with an engine about the same size as mine so I guess that the simplest answer would be to follow Dave Watkins and make an Idris one. This would keep the boiler/engine size about the same although if it was over boilered I'd not run out of steam and I could always turn the gas down a bit!
Thanks for your input Havoc, I can see the problem more clearly now.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 27, 2008 3:47:41 GMT
G'day all, I'm no expert and for that reason I have been study the AMBSC Codes for miniature and subminiature boilers before lauching into a boiler for a gauge 1 loco. It appears to me that both designs may be light on for staying of the top plate and that the Climax design lacks staying of the furnace crown plate. Equally both designs would not meet code because of the butt joints between wrappers and end plate/crown sheet unless the joints are brazed not silver soldered. For anybody contemplating building a boiler I would recommend getting a copy of these codes, they are quite readable and very instructive, eminently practical. See www.ameng.com.au/retail-books2.htmInstead of the cross tubes or bent tubes you could use thimbles or Field tubes. Regards, Ian
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Post by modeng2000 on Jan 27, 2008 7:46:29 GMT
Thanks Ian, although the loco would only be used on a private track I shall get in touch with a club boiler inspector to make sure that I am not making trouble for the future. Things have moved on since some of these designs were published. These boiler tests sgcox.site.net.au/ritg/boiler-tests.pdf show that butt joints can be adequately strong if made properly but it is not always possible to know the joint is sound without taking it appart!!! John
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Post by mackintosh on Jan 27, 2008 8:23:34 GMT
Hello John I am at present building 3 16mm De Wintons to a slightly modified Dave Watkins design. But I intend to use his boiler as is. I am just in the process of getting the third running on air before starting the boilers. So if your boiler is started before mine please post any problems encountered and I will do the same. I would post a photo but I don,t want to hijack the Gauge 1 forum. Bob
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Post by modeng2000 on Jan 27, 2008 10:44:39 GMT
Hi Bob, the loco I'm trying to build is to the 1:22.5 scale so it is a bit larger than yours. While looking around for boiler designs it now seems to me that Dave Watkins's boiler is probably the one to go for but I am fairly new to boiler making and hence my postings to the forum. Making the boiler involves quite a lot of effort and so I wouldn't want to start something that would end up in the scrap box.
I'll try to keep you informed of any progress I make but it will not be started for a short while.
You could send me a private e-mail to save 'hijacking' the Gauge 1 forum.
John
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Post by havoc on Jan 27, 2008 11:04:10 GMT
The large pipe in the middle isn't only for the gases to escape, but it also a stay between the top of the firebox and the top boiler plate. The unsupported area is not very large, certainly not larger than in a boiler stayed with rods. Brazing and silver solder are used interchangably these days. Meaning using a silver bearing solder with 30-40% silver content, not the 2% soft solder. Also possible but more work! I have my doubt about field tubes in boilers as small as these. Don't forget that you cannot scale water. Bubbles might block the flow in field tubes. Also see the last link I added, there they compared a kind of thimbels with porcupine quills and the quills where better and easier to make. Well, neither can you tell with a flanged boiler! Unless you x-ray all joints there is no telling if full penetration has occured. That is one of the reasons all boilers should be water pressure tested regulary. I prefer flanged boilers for other reasons, like you can drill through the flange and insert a small rivet to hold everything together while you braze. But it also introduces possible defects during the flanging. Like overstressed bends. Links you might find useful: users.bart.nl/users/summer/16mmngm/Articles_htms/ColinBinnie/DeWintonBoiler.htmusers.bart.nl/users/summer/16mmngm/Articles_htms/porky.htm
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abby
Statesman
Posts: 925
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Post by abby on Jan 27, 2008 11:25:48 GMT
Mack and Modeng please post your pictures , there is little enough in the G1 section. Now that the weather is improving I am itching to get on with my own project and it looks like boiler time too.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 27, 2008 11:59:22 GMT
G'day John Thank you for the reference to testing of sub-miniature boilers. It is most encouraging but I note it is dated 2004 whereas the Code for sub miniature boilers is dated 2006. The Code writers knew about the work bit did not give undue credence. Granny engineering? This code AMBCS SMB code does allow unflanged end plates, but make no reference to butt connected end plates, for barrel diameters to 77mm, however the unflanged endplates need to be up to 2mm thick see clause 2.4.5. this is only for boilers up to medium pressure vis 520kpa 75psi. The implication is that for larger diameters the end plates will be flanged. Note also the need to stay the end plates. Talking to a tame boiler inspector would be a good idea. Good luck Regards, Ian
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Post by havoc on Jan 27, 2008 12:11:28 GMT
Can you clarify this a bit please? What would be the difference between "unflanged end plate" and "butt connected end plate"? I don't have that code as I have to work to another one so I might miss any drawings.
Keeping this for smaller boilers makes sense as for larger boilers the thickness would become larger as well to keep an unflanged plate safe. That would mean it would be much harder to heat than a thinner flanged plate. Also heavier and more difficult to work.
Yes please, post them. All extra information is welcome.
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Post by baggo on Jan 27, 2008 13:04:40 GMT
It seems to be common practice to use butt joints in gauge one boilers. Roger Thornbers's design for his Evening Star boiler (and his other designs I think) uses a plain butt joint where the boiler barrel meets the backhead and the front tube plate is just a plain disc soldered into the barrel. The working pressure is 60psi (4 Bar). I think the Gauge 1 Society designs also use butt joints. Maccsteam Ltd sell ready made boilers to all these designs so the method of construction must still be acceptable.
The use of the word 'brazing' nowadays is a bit misleading and perhaps shouldn't be used in connection with boiler making. Brazing refers to the use of brass spelter which, although commonly used for boiler making in the old days, is a definite no no today! I believe Keith Wilson adopted the term 'silver brazing' in his descriptions to mean silver soldering.
John
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Post by modeng2000 on Jan 27, 2008 14:40:57 GMT
It is good to see some activity on this board isn't it. I really appreciate all the help and suggestions. Like I said, I would rather not make a lemon. Now I can look at the various designs with a more informed eye. Otto Hadorn's Climax boiler if altered to use more up to date construction would be my choice as it is part of the overall loco design. I could use the De Winton though I think it is all round about 20% smaller. John
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Post by mackintosh on Jan 27, 2008 16:25:39 GMT
John Further to my post earlier I forgot to mention the Dave Watkins boiler uses standard plumbers copper tube sizes which I found very easy and cheap to come by if you know a friendly plumber. I also considered putting in some cross tubes to improve steam production but then wondered if this would restrict the air flow up the center tube. Bob
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Post by baggo on Jan 27, 2008 17:49:46 GMT
Hi Bob,
That reminds me of a question I've thought about before - is ordinary plumbing copper pipe seamless? I've always wondered about it's suitability for boiler work.
John
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Post by havoc on Jan 27, 2008 18:24:43 GMT
AFAIK it is seamless. What would it be otherwise? Even if it was welded I would find it very suitable. But that would show. I doubt they would polish inside and outside so you would not see it was welded.
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Post by mackintosh on Jan 27, 2008 20:41:37 GMT
John & Havoc Yes it is seamless drawn just as the larger stuff. I went on a Beano as an apprentice to Thomas Boultons copper works at Froghall very interesting. But the same as all these works only a shadow of it's former self. Bob
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jan 27, 2008 20:57:36 GMT
G'day Havoc
What would be the difference between "unflanged end plate" and "butt connected end plate"? From my reading of the test report the unflanged end plate sits inside the barrel and is silver soldered in. Whereas for the butt connected plate, the plate is larger than the barrel and the end of the barrel butts up to it. For the former no mention is made of crimping in the end of the barrel to mechanically retain the endplate. You will note that for the Climax boiler the end plates appear to be butt connected.
I will open Havoc's other links in a minute. I have seen an article extolling the benefit of quills for effective heat transfer in small boilers; this was more in relation to pots and smithies.
I agree regarding the flue being a stay but even then the top sheet may be too large unless of greater thickness, stayed or made tori-spherical.
I know it is common the term "silver brazing" is used for silver soldering; but not in the Codes. Silver soldering uses silver alloys (>15% silver) also known as hard soldering. Brazing uses a bronze alloy. Both materials are covered in Australian Standard AS1167.1
Good to see some discussion, thanks brothers.
Regards, Ian
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