My first boiler

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John Antliff

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My boiler was made using a single temperature silver solder which contained 45% silver with cadmium. It has been my experience that cadmium greatly increases the "wettting" ability of the silver solder giving better penetration in joints and more robust/even menisci. There are some basic rules to observe to achieve optimum joints those being 1) Extreme cleanliness i.e. absolutely no oil or grease on the surfaces. 2) Good tight self-holding joints with gaps no greater than 5 thousandths of an inch. 3) Use a high melting point flux. 4) DO NOT OVERHEAT the assembly - better to use an LPG burner or paraffin blow lamp rather than oxycetylene which will require much skill if overheating is to be avoided.

The use of Kawool as an insulator ensures that heat is retained and cold drafts eliminated. The solder will flow towards the heat source so use the torch to draw and melt the solder accordingly. Never stick the solder rod into the flame directly but apply it to the surface of the joint away from the flame. This will ensure that the metal is up to temperature at that point and the solder will melt and flow towards the flamed area.

As mentioned by another member, the re-melt temperature of of an existing silver soldered joint is about 65 degrees Centigrade higher than the original melt temperature (typically 635 C) and with an LPG burner like a Sievert, it is quite easy to revisit/re-do a joint with the same solder without re-melting the original solder. The LPG gas available in New Zealand is a mixture of Propane and Butane, less of the former usually and as the gas is consumed the Propane burns hotter than the Butane and also vaporises in preference and so if the container is not shook up regularly one can be left with only Butane and a cooler flame. Use a pickling bath to clean the job after soldering - I use citric acid which works well and fairly quickly without fear of corrosive damage to myself or my clothing.
 

John Antliff

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If you always solder with the workshop door open and refrain from sniffing the fumes then you will not receive a dangerous exposure to cadmium even over a lifetime of use. The health & safety issue really only applies to workers being exposed to cadmium fumes on a daily basis. As a hobbyist one would have to deliberately sniff the fumes regularly before the level of ingested cadmium cause any problems.

I bought a bulk load of 45% silver solder over the internet 4 years ago. I think it was being released from a business because of the H&E considerations and this might explain why I got it at a quarter of its value. I have enough to make about 8 more 6 inch boilers of this kind, far more than I will probably use before I permanently hang up my overalls for good!
 

Rudy

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Hi guys,
Hav had some time in the shop lately and did some progress on my boler. I have no plans, so I just build as I go.
Did a trial assembly before I'm going to paint some of it.
Since this is my first boiler, I have no experience running a steam engine on live steam, so I'm exited about how it will work. If there is some obvious flaws in the construction, I will appreciate some feedback. I have been looking at a whole lot of builds though, so I believe it can't be all that far off.
I found it both easier to make and better looking to use rivets rather than bending the brass sheets and silver solder. Sheet metal work is actually not all that simple to get right without having the proper tools.
Made all the valves and fittings to.

Rudy

Boiler trial assembly.jpg
Boiler main parts 2.jpg
Boiler main parts 1.jpg


The Stuart 10V sitting by and patiently overlooking the progress, longing to breath in some real live steam!

Boiler main parts 3.jpg
 

aka9950202

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That is a well made boiler. Congratulations.

Make certain to pressure test it before use. I hope to see a video featuring it soon.

Cheers,

Andrew in Melbourne
 

minh-thanh

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Wow...Wow...
Great !
And Thanks for the information of the boiler
I have questions: all parts of valve ( body, handwheel ...) : you made yourself?
Pressure gauges: you bought it? or?
Thanks
 
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Rudy

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minh-thanh, first, I did buy the gange. The valves is a compilation of others design blended with my touch. Easy to make. I did cheat a bit and started with 12,7mm (1/2") bras balls. However, turning it your selves is not all that difficult. Doesn't need to be ball bearing-round. I'll put up a photo of the hand sketches I did while making them.
In the mean time, here is a picture of the parts.
The hand wheel is easy to make if you have a rotary table in the mill. If not, you can drill all 12 holes first and turn it down afterwords. I did silver solder two of the fittings to the ball, but I guess that wasn't totally necessary.
I tried to silver solder three parts to the ball without having made threads first and found it very difficult to solder several parts together at the same time. This way it was very easy.
Let it be said, I haven't tested these valves yet! :)
IMG_20200101_201900.jpg


This is how I started with the ball so I could hold it in the wise. Epoxy glued a 6mm washer to one side of it and pressed it against a soft aluminium piece at the other side. This particular picture is taken of another version I'm working on, but you got the "picture" of how I'm holding it.
Ball in wise.jpg


Rudy
 

Rudy

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That is a well made boiler. Congratulations.

Make certain to pressure test it before use. I hope to see a video featuring it soon.

Cheers,

Andrew in Melbourne
Andrew, do you have any idea of what pressure this boiler would hold? I was planing on setting the safety valve to 40 psi, but I assume the boiler will take much more.
Rudy
 

minh-thanh

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Rudy !
Thank you for the information, explanations and pictures . That helps me a lot
I have questions :
Boiler trial assembly.jpg

1 - is it a safety valve? Do you have pictures of each part of it ?
2 - How thick is that glass tube? where did you buy it ?
I've never made a steam boiler like that, so there are many silly questions
 

Rudy

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Minh Thanh, yes, it's a safety valve. Very simple and reliable design. Easy to make. The glas tube is 4mm outer diameter. Bought it on Ebay. I have some hand drawn sketches for it all that I will put up here when I'm coming around to it.
Rudy
 

lathe nut

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you do good work, that really looks great, thanks for sharing, Joe
 

JCSteam

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That's a really nice boiler, very much along the lines of the Stuart boilers with your own flair added.

It will be really nice to see this one running. One question though, how is the boiler/firebox eventually fixed to the base plate?
 

Rudy

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JCSteam, Thanks, Your'e right, It is greatly inspired by the now reintroduced Stuart 504 boiler. Haven't figured out how to fix it to the base plate yet. Probably four small brackets on the inside, screwed down in threaded holes the 5mm base.
Stil not decided on the type of burner I will make. Has to be something very silent because the Stuart 10V engine it will give life to runs very slow and quiet and I don't want anything to spoil that. So a spirit burner is a good candidate.
Rudy
 

aka9950202

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Andrew, do you have any idea of what pressure this boiler would hold? I was planing on setting the safety valve to 40 psi, but I assume the boiler will take much more.
Rudy
Rudy, No I don't know the working pressure but models seem to be between 50 to 70 psi. The designer would calculate the materials for a pressure.

Cheers,

Andrew in Melbourne
 

Shopgeezer

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Nice looking boiler. Hope it works well for you. I read an account of boiler making where the builder used normal brazing rod instead of silver solder on his boiler so that the soldered seams matched the copper when it was polished. Is their any reason not to braze a boiler with the usual brazing rod?
 

Rudy

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Nice looking boiler. Hope it works well for you. I read an account of boiler making where the builder used normal brazing rod instead of silver solder on his boiler so that the soldered seams matched the copper when it was polished. Is their any reason not to braze a boiler with the usual brazing rod?
I have no idea..
Rudy
 

Peter Twissell

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What is "normal brazing rod"?
I have used Sifbronze, which is copper coloured. I would expect the most basic brazing rod to be brass, but most if not all available rods are alloys of more than just copper and zinc.
 

Shopgeezer

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Yes there are many brazing alloys but from my perspective the “normal” brazing rod we have around the farm is primarily brass as opposed to silver solder. I would have to do some research to see what the actual alloy is.
 
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