Chimneys & Steam Pipes : Copper or Brass : Why ?

Hello,

I'm building the Jenny Wren combined engine and boiler in Stan Brays book "building simple model steam engines". My third engine. A picture of the front cover of the book is here and the picture could be a schematic for the Jenny Wren.

Both the curved pipe and the chimney in this model are in contact with steam. The chimney (Brass) rises up the centre of the boiler tube and provides an internal wall concentric with the outer wall of the boiler. The curved pipe (Copper) takes steam from the boiler to the engine. The boiler body can be either brass or copper.

Some Jenny Wrens made by other folk are here

What is the logic behind using brass or copper for different parts of a boiler or steam engine please - are there any instances where one is better than the other ? It seems permissible to allow live steam to make contact with either material. Fittings / connections / safety valves / are generally brass rather than copper ? Copper is a bit soft and sticky to cut ?

Any books or websites I should be reading to better understand material selection ? I've got the Stan Bray and Tubal Cain "Simple Model Steam Engines" books already.

Thanks

Bill

Don't forget this book was written some time ago and things have changed. It is no longer accepted practice to use brass in boilers or for boiler bushes etc that are in contact with live steam/water directly as a permanent part of the boiler. So tubes and bushes need to be copper or bronze. Brass is still used for fittings that are screwed into the bronze bushes because they can (and must) be regularly removed and inspected for corrosion.

In the past the choice was only limited by appearance and availability. Early domestic plumbing was iron or lead not copper so bits of copper pipe were less often available and brass was as likely to be bought since it looked prettier.

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Is the risk of a brass boiler that great on a boiler with a volume of less than 9cc? This is a lot smaller than a Mamod or Wilesco brass boiler.

Brian

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For the record in the UK under current club rules it is perfectly acceptible to make boilers out of brass. They are much stronger and thus can be made much lighter than copper, and are a lot tougher to work with. I do get asked to make boilers frombrass from time to time but dont like making them! Bushes are all bronze.

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Be cautious if you acquire a vintage toy engine, with a brass boiler, and want to steam it. I have a German one that belonged to my father-in-law. What appears to be a brass boiler is in fact steel dipped in brass! It has rusted through from the inside. If you find one that looks ok, wave a magnet near it for reassurance.

Maurice

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Hi Bill, yes,I also have the original box. Most of the label is in German. Assuming that what I am reading is the maker's name and not a German word for a specific type of engine, then it was made by. "Gegrauchsanweisung". The country of origin is Bavaria, and the engine is called "The Star". It still has the original meths burner, with its filling measure. My late father-in-law and his two brothers used to play with it.

Regards Maurice

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Could that be "Gebrauchanweisung" (instructions for use)?

Brian

Could well be! I really have no idea. Thats all there is on the label apart from the aforementioned instructions.

Maurice

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Thanks for all the tips.

Bill