Cast boiler components

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jscarmozza
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Cast boiler components

Post by jscarmozza »

The other day I was talking to my live steam buddy who is also my casting partner about an upcoming casting session and the conversation wandered to the pros and cons of cast boiler components similar to those used in the boilers that Little Engines made. Other than casting flaws or a poor choice of alloy (which can be huge problems), what would be wrong with some cast boiler components, provided that their soundness could be assured? We wondered if (pure) copper castings would be better than the bronze that LE used? I have from time to time produced some very porous brass castings, but the few copper castings I made were uniformly solid and ductile. We're not planning to build a boiler, we're just trying to understand what constitutes good practice and why some techniques have been abandoned.
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gwrdriver
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Re: Cast boiler components

Post by gwrdriver »

I built my first boiler (6" copper) using bronze castings to my own patterns (and design.) One of the reasons was that we had a superb and cooperative local non-ferrous foundry, and I felt I wasn't up to what appeared to be the formidable job of forming the heads from sheet. The bronze was of the alloy that was then being used for memorial plaques and it machined beautifully.

The boiler was a success in that it hydro'd to 200psi and steam tested to 150, but for a number of reasons including youth, ignorance, lack of skills, proper tools, and poor planning, it ultimately proved to be unusable for the locomotive project. Lessons learned the hard way were a bit cheaper way back then, but even so I got my money's worth out of it in lessons.

The cast heads weren't the problem, . . in fact as heads they performed well, but all things considered I decided I'd be better off to form the heads on any future copper boiler. Proper understanding of how to do it and a little practice, and a good torch, made forming simpler and more cost-effective than using castings.
GWRdriver
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jscarmozza
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Re: Cast boiler components

Post by jscarmozza »

Thank you, hearing from someone who actually made a boiler with castings is what we were looking for. So if I understand, you're saying that castings are appropriate for LE who's going to make a lot of units, but for a one of a kind custom boiler it's easier to fabricate all of the components. Makes sense, and you don't run the risk of a bad casting showing up after you finished making the boiler. In your opinion, do you think a boiler made with sound castings is equal to a fabricated copper sheet boiler? Also, do you remember if you had a hard time silver soldering the castings? I would think that the heavier cast parts would soak up a lot more heat and make it hard to evenly heat a joint with copper sheet. Thanks, John
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Builder01
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Re: Cast boiler components

Post by Builder01 »

If you are considering creating castings to avoid using wooden formers to create flanged tube sheets, I think it is probably more trouble than it is worth. Creating flanged copper tube sheets is not hard, in fact I found that creating them for my boiler was actually pretty easy and fun. Try an easy one first, like the smoke box tube sheet, as it is usually a plain round sheet. Then do one for the fire box. The formers do not need to be metal, hard maple works just fine. These are the first formed copper tube sheets I have ever made and they turned out pretty nice. It's not hard to do.
Photo 1.png
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If you are interested in more photos of flanging a copper sheet, here's the link to my website:
https://supersimplex.yolasite.com/Flanging-a-Plate.php
jscarmozza
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Re: Cast boiler components

Post by jscarmozza »

Nice work Builder. I don't have the skill or confidence to take on a boiler project. I was just wondering why no one appears to be using castings now a days, had there been an experience issue with their use in service like Sil-Phos, or with no one producing a large number of boilers like LE, is it just not practical? My buddy was thinking it would be more economical, but after thinking about it I don't think that would be the case at all. Thanks
Marty_Knox
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Re: Cast boiler components

Post by Marty_Knox »

I studied Non-Destructive Testing in college. When I had my Radiography class I borrowed a Little Engines cast one piece firebox for their 1" scale 0-4-0/0-6-0. We X-Rayed it - the stays had not joined the way they were supposed to. The wires from the cores were still inside.
There is no way I would use it for a boiler.
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gwrdriver
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Re: Cast boiler components

Post by gwrdriver »

On Little Engines castings, . . . LE began using boiler castings to make boiler building easier, and faster, for the amateur, which reached a pinnacle of complexity in the all-in-one cast fireboxes for the the American and CP Huntindon. IIRC they also produced one for the 1" scale 0-6-0. A fellow club member built a Huntingdon in the 1960s, using the LE cast firebox, and the boiler construction was difficult at best. He worked for a large industrial company and had their plant welding (and brazing) shop at his disposal, so skills and heat were abundant. But I don't think he ever achieved a reliable seal as the casting was full of inclusions which grinding never go to the bottom of and it ended up being more Sil-phos than bronze. (At that time Sil-phos was still "OK")

What LE did was to attempted to make boiler construction easier, and more attractive, for prospective builders by transferring the difficult work, and responsibility for soundness and fitness for purpose, to the foundry. This is fine, as long as the foundry can produce a sound and fit-for-purpose product at a reasonable cost. When either one of those gets out of whack, in this case ultimately both did, it's no longer a workable or affordable solution for the builder.

FYI, IIRC in the late 1960s the cost of the LE cast firebox for the American/Huntingdon was $65.
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Bill Shields
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Re: Cast boiler components

Post by Bill Shields »

In today's world of water jet cutting by mail I have found metal formers to be an easy route to go. Yes. I still have and use wood formers. .but the waterjet is more accurate than my band saw work.

But then again if you have a friend with a CNC router you have the best of both worlds
Too many things going on to bother listing them.
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Builder01
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Re: Cast boiler components

Post by Builder01 »

If you can use a band saw and a disc sander, and can sand up to a pencil mark, you can make wooden formers. That's how I did mine. For a nice radius for the flanged areas, you can use a radius cutter for wood. Use a drill press, milling machine, or router to run the cutter around the edge. No need for CNC or DRO, this is simple copper smithing.

My maple, and some poplar formers, could probably make another five boilers! They actually wear quite well.
jscarmozza
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Re: Cast boiler components

Post by jscarmozza »

Geez, I hope my LE Atlantics' boilers don't have casting issues. Thank you for the insights, I guess I can conclude that although castings may work, they're not the best option.
John
jscarmozza
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Re: Cast boiler components

Post by jscarmozza »

Builder, just out of curiosity, what scale is the boiler and the thickness of the copper sheet you're forming? How frequently do you anneal the copper to get those nicely formed corners? You're doing nice work. My buddy and I have been discussing boiler making quite a bit lately and he finally confessed that he's considering making a replacement boiler for a 1" Tom Thumb that's he has. Thanks, John
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gwrdriver
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Re: Cast boiler components

Post by gwrdriver »

FYI, my last couple of boilers were in 1/8" sheet and I annealed at least 3x for simple bends, more as-necessary for complex (reverse, compound, etc) curves. The guide-line should be to anneal, when the copper stops moving with normal hammer blows. At that point you might be able to get a little more movement with bashing blows, but that's not good for the copper, or your elbow. An anneal takes 5 minutes and makes everything go much easier. I quench my plates red-hot, or near that, which blasts most of the black oxide off.

My form material preference is steel, helped along by being in my truck and finding a plank of new 1/2" HRS in the middle of a road. My second preference is well-seasoned Oak, plentiful in these parts. And as you can see in Builder01's photos of his excellent work, you will always need a backing plate.
GWRdriver
Nashville TN
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