Metallurgy of Steam Engines

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SteveM
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Re: Metallurgy of Steam Engines

Post by SteveM » Thu Feb 08, 2018 7:19 pm

Bill Shields wrote:
Thu Feb 08, 2018 5:19 pm
absolutely the best place to start..a solid proven design that doesn't require a home mortgage or 3 decades to build.
Not bad looking either:
Raritan.jpg
Steve

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backyardrails
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Re: Metallurgy of Steam Engines

Post by backyardrails » Thu Feb 08, 2018 8:14 pm

Sorry, I had to post this one. The Raritan has alway been my favourite. It steams well and purrs nicely along the track.
Bernie
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FKreider
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Re: Metallurgy of Steam Engines

Post by FKreider » Thu Feb 08, 2018 8:39 pm

Thank you to everyone who has responded so far and I appreciate all of the advice. It appears the general consensus is that Brass/Bronze and cast iron are much preferred over aluminum which I expected to be the case but it doesn't hurt to ask.

What I struggle with when reading forum posts or a build construction article sometimes the author says use "brass" or "bronze" but they do not give any further detail. When calling a local metal shop they always ask what "type" of steel or other material I am looking for and then I quickly feel foolish as I haven't a clue. I have a similar experience online; going to one of the online supply websites you will find many different alloys to choose from.

https://www.onlinemetals.com/productgui ... sguide.cfm

https://en.wikipedia.org/wiki/Brass

From the reading/research I have done I am thinking that in the model engineering world "Brass" castings are typically "Red brass" otherwise called "gunmetal" and any brass bar stock used is C360 "free machining brass."
-Frank K.

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Bill Shields
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Re: Metallurgy of Steam Engines

Post by Bill Shields » Thu Feb 08, 2018 8:48 pm

Just stay away from aluminum bronze unless you really know what you are getting in to.

WJH
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Re: Metallurgy of Steam Engines

Post by WJH » Sat Feb 10, 2018 7:06 am

don't use brass for steam fittings

FKreider
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Re: Metallurgy of Steam Engines

Post by FKreider » Sat Feb 10, 2018 11:44 am

WJH wrote:
Sat Feb 10, 2018 7:06 am
don't use brass for steam fittings
It appears most model steam fittings are "red brass" which is really a bronze alloy?
-Frank K.

WJH
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Re: Metallurgy of Steam Engines

Post by WJH » Sat Feb 10, 2018 2:19 pm

Bronze is fine. This was a discussion on Kozo's A3 book where he said to use free machining brass. Someone please correct me if I am wrong, but the high steam temperatures over time caused the brass to break down?

Harold_V
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Re: Metallurgy of Steam Engines

Post by Harold_V » Sat Feb 10, 2018 4:41 pm

FKreider wrote:
Sat Feb 10, 2018 11:44 am
It appears most model steam fittings are "red brass" which is really a bronze alloy?
Red brass is most likely the old standard 85-5-5-5 alloy, which consists of copper, lead, tin and zinc.
Color, alone, can't be relied upon to determine whether an alloy is bronze or brass. In the case of "red brass", as above, it's both bronze and brass.

The line that separates bronze from brass is fuzzy, although a zinc alloy is generally considered brass, while a tin alloy is considered bronze.

Bill suggested one not tangle with aluminum bronze. True enough, but it's a walk in the park when compared to manganese bronze, which is the copper alloy equivalent of titanium when one must do the machining.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Greg_Lewis
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Re: Metallurgy of Steam Engines

Post by Greg_Lewis » Sat Feb 10, 2018 9:24 pm

Rich_Carlstedt wrote:
Thu Feb 08, 2018 4:26 pm
A number of years ago, and I believe it was here on Chaski, there was a discussion about smoke boxes and materials.
Temperatures were measured on various locomotives and some were in the 700+ (F) range and others only 550 degrees.
I do not remember if this was also related to coal, oil, or propane fired locos.

...
Rich
That was back in 2003. I did a test with an infrared thermometer. You can find the data here:
http://www.chaski.org/homemachinist/vie ... box#p16207

The flaw in my test is that I did not test all locos under different conditions, i.e. running uphill under load, idling in the yard, etc. I suspect that running uphill with the increase in exhaust results in a slightly cooler smokebox than sitting in the yard. The average reading from 23 readings taken from the outside surface of the smokebox is 323°F. The high extreme was 470°F, the low extreme was 249°F. There was one engine whose readings were way high and was not included in the average. All the engines were either oil or propane.
Greg Lewis, Prop.
Eyeball Engineering — Home of non-interchangeable parts.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

Abby
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Re: Metallurgy of Steam Engines

Post by Abby » Sun Feb 11, 2018 6:52 pm

Another point that has not been mentioned is the fact that brass , red or yellow and most bronzes are readily soldered with soft or hard solders.
Aluminium is not easy to solder (yes it can be done but not as easily) .A beginner , who is probably cost conscious , will almost certainly need to repair mis-machined parts rather than scrap them.
Dan.

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