4 years of Silver Soldering Hell

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Carrdo
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4 years of Silver Soldering Hell

Post by Carrdo »

After four years of silver soldering hell...

My 1" scale (4-3/4" gauge) all copper Yankee Shop Atlantic boiler is complete and tested hydraulically to 200 psi with no leaks whatsoever.

It returned home today.

This boiler has quite a story to tell which I can go into if desired, but to sum up, we changed the original design somewhat in the process, corrected all of the errors made by the original builder; it used nearly 0.65 kilograms of silver solder to put it all together employing the old (now unobtanium cadmium based) Easy Flo 35 and 45 grades of silver solder; we calculated that at the hydraulic test pressure, there was about 3.5 tons of buckling pressure on the crown sheet and at that test pressure there wasn't the slightest sign of movement/distortion/distress anywhere on the boiler.

It took the three of us to do the job - I actually did next to nothing except to record a lot of the process. It was poor Ted McJannett of MPP (the proprietor of the former Miniature Power Products), who literally spent days and weeks to get the optimum fit on all of the parts (0.003" gap) and then he had to do the actual silver soldering work along with Wolfgang Habicher (who is a professional mechanical engineer with extensive design experience in heavy mechanical and pressure vessel design) who came up with the revised boiler design and who did the stress calculations to prove that it would work.

Locomotive copper boiler silver soldering is 90% preparation work and having all of the right equipment to do the job as well as doing the initial planning and thinking on how it is all going to go together so one does not get into a situation where you can't do something or get at something to silver solder it. Even with all of the above, there were many interesting moments which this boiler threw at us as it wasn't going to give up without a fight!
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Bill Shields
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Re: 4 years of Silver Soldering Hell

Post by Bill Shields »

Been there -> done that and could not agree more...(did 2 copper boilers last year)

It's a thankless job but somebody's got to do it.

I like putting the shell on a lazy susan spinner and putting multiple torches on it as necessary...yes a friend (or 2) really makes the job go easier.

and when it's done and not leaking...it's Miller Time!
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keyrouteken
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Re: 4 years of Silver Soldering Hell

Post by keyrouteken »

Carrdo states the following :
""Locomotive copper boiler silver soldering is 90% preparation work and having all of the right equipment to do the job"" !

Well-- As my grandfather completed each of his engines with a copper boiler (he built close to 30) he took the boiler to his employer in later years (the Southern Pacific) and used their Oxacetelyne gas rigs to silver solder the boilers. I guess that's having the "right equipment", huh ? Then he would take the hot boiler and dip it in a vat of Sulfuric Acid. After which he would put it in a tub of cold water to rinse everything off the surface. Boy, it sure looked pretty.

Some of his early boilers were done in his basement workshop with a small handheld torch. Those big torches used to really scare me when a little kid when he first lit them off, before he adjusted the valves for a pin point flame. Ah yes--Memories of the old days !

Ken Shattock
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SteveM
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Re: 4 years of Silver Soldering Hell

Post by SteveM »

Carrdo wrote:Locomotive copper boiler silver soldering is 90% preparation work and having all of the right equipment to do the job
Like painting a car. While the last coat can mess things up, it's not the main reason the paint job looks so good - it's everything that went before.

Nice job.

Steve
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Bill Shields
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Re: 4 years of Silver Soldering Hell

Post by Bill Shields »

I use oxy-acetylene also (with a BIG ROSEBUD) to bring up to temperature -> but you have to be very careful to not overheat it and damage the solder or you can be in big trouble.
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Carrdo
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Re: 4 years of Silver Soldering Hell

Post by Carrdo »

Some of the many photos taken of the major silver soldering operations with the two hero's hard at work.

Yes, we used propane to preheat the copper and a small rosebud oxy/acetylene tip having a neutral flame to flow the silver solder.

But you have to know what you are doing. One has to keep the rosebud tip moving all of the time, if one hesitates for even a fraction of a second, you will burn the copper. Likewise, one has to keep the propane torch moving all of the time as well to get an even preheat. Ted was continuously informing Wolfgang where and for how long to preheat the copper before he added his oxy to flow the silver solder.

That is why I leave this to the experts who have both the experience and the skill.
Attachments
Preheating the Copper with Propane and Flowing the Silver Soldering with a Neutral Oxy-Acetylene Flame.jpg
After Silver Soldering Crown Plate Girder - Stays to the Boiler Outer Shell.jpg
Wolfgang
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Re: 4 years of Silver Soldering Hell

Post by Wolfgang »

Weeeell, now that the job is done, it wasn't thaaat bad.:-))

Apart from the cursing and swearing along the way it was very pleasant to work on that boiler, especially since this was the first large locomotive boiler I'd helped build.

My CPR Hudson boiler is steel and was fabricated by a club brother from the Woodstock club (Golden Horseshoe Model Engineers), Ontario, in 1985 or so.
paralleler
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Re: 4 years of Silver Soldering Hell

Post by paralleler »

Fortunately there are still some that know how to do this. Attached are photos of a copper boiler built in the mid-1990s by Dave Gumz of GGLS for his Ten Wheeler. Fortunately someone kept these gems rather than tossing them. Remember the closing scene of the original Indiana Jone's film? Oh the history that could be packed away in warehouses & attics.
Attachments
4-6-0 Boiler Sub-Assemblies
4-6-0 Boiler Sub-Assemblies
4-6-0 Boiler Stays
4-6-0 Boiler Stays
4-6-0 Boiler Test
4-6-0 Boiler Test
4-6-0 Boiler Test
4-6-0 Boiler Test
A Proud Gentlemen And His Handiwork
A Proud Gentlemen And His Handiwork
Steve Bratina
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Re: 4 years of Silver Soldering Hell

Post by Steve Bratina »

So what were all the errors from the original builder. I would hate to be standing beside one done to original plans when she blew up. Would you recommend condemning these older boilers?
Marty_Knox
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Re: 4 years of Silver Soldering Hell

Post by Marty_Knox »

Steve Bratina wrote:So what were all the errors from the original builder. I would hate to be standing beside one done to original plans when she blew up. Would you recommend condemning these older boilers?
The original drawings showed corner to corner joints with no flanging. They also recommended using Sil-Fos.
Wolfgang
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Re: 4 years of Silver Soldering Hell

Post by Wolfgang »

Steve Bratina wrote:So what were all the errors from the original builder. I would hate to be standing beside one done to original plans when she blew up. Would you recommend condemning these older boilers?
Hello Steve!

One error by the original builder was in the details of flanging the various plates. He cut relief notches in the corners to ease the flanging. To correct this took an enormous amount of time; Ted filed out the notches to sound metal with a dovetail, then filed and fitted pieces to fill the slots. The dovetail was necessary so the bits wouldn't fall out during soldering...

Also, the fire box had been (partially) riveted which, in my opinion, is a serious mistake for sound silver soldered joints. So we drilled out the rivets, cleaned everything up, fluxed the joints, and assembled the thing with copper screws Don and Ted made to suit from 1/4 " square copper bar. Thus we could control the gaps in the joints which are necessary for the solder to be wicket into the lap joints. Rivetting the joints bashes everything tight with no room for the solder to flow...

Then there was the main crown stay "girder". This is what it is called in the hobby literature but in this application where this member is continuously attached to the boiler shell and the crown sheet, this item is a tension member, not a beam or a girder. And this item is subjected to serious tension forces along its length: the crown sheet is subjected to a load of 7,000 lbs during hydro test at 200 psi! Anyway, this stay had very large holes drilled through the web of this I-beam section, thus seriously compromising its transverse tensile strength. We attached copper angles on each side to vertically bridge these holes, replacing the metal that was removed by drilling.

And then there were the fire box stays which were threaded into the boiler shell AND the fire box wrapper. These were a nightmare to put in and take out for trial assembly. I seem to recall that these stays took perhaps half of the time we spent on fit-up... In my opinion 4 or 5 threaded stays on each side are sufficient to prevent the sheets from moving too much during soldering; the remainder may just as well be threaded into one sheet only so that they don't fall out when things get hot for soldering.

Added to all this was our screw-up on carrying out the final joint: The mud ring. This ring is basically 4 copper bars about 1/2" x 1/2" section and length to suit, with the ends properly fitted...

Well, we assembled all 4 pieces, properly fluxed and fitted, and started soldering at one corner of the throat plate. By the time we worked our way all the way around the mud ring the flux on the last piece was spent and no longer active in cleaning the joint. Consequently we couldn't get the ###*** solder to flow. Suffice it to say that it took considerable head scratching and strong language to overcome and solve this difficulty: Ted set-up the boiler on his milling machine and milled out the offending joints with a 1/32" thick slitting saw. After fluxing and closing the gap the soldering was completed without any more aggravation.

On the NEXT boiler we do, and indeed there is one waiting in the wings it appears, we will fit the mud ring one bar at a time and solder it. Temporary spacers will be in place for the remainder of this joint. Proceeding in this manner will permit cleaning of all surfaces and the application of fresh flux.

Having said all this I am still of the opinion that all in all this is a very sound and solid boiler, and have no concerns regarding its safety when fitted with appropriate safety valves and operated in a knowledgeable manner.

For an old boiler I would suggest a hydro-static test with the boiler removed from the locomotive so that all flat surfaces, inside and out, can be checked for flatness or variance thereof before and after subjecting the boiler to the test pressure. What we are interested in is any change in shape at the test pressure. This change in shape had better be very small or practically non-existing for a model boiler. Serious deformation of any flat sheets would be grounds for further investigation and possibly condemnation of said boiler.

Wolfgang
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baggo
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Re: 4 years of Silver Soldering Hell

Post by baggo »

I think a lot of these 'bad practices' in copper boiler making came from LBSC and perpetuated by the likes of Martin Evans etc. LBSC would recommend rivetting together sub assemblies such as the outer shell and inner firebox before final silver soldering. He also recommended making tubes a drive fit in the tubeplates which would obviously leave no gap whatsoever for the solder to flow into. He was also quite sparce with stays compared to what would be recommended nowadays. I presume that builders in those days were happy with a lower safety factor than we would accept now.

With modern copper boilers, most builders use plain copper rivets for the firebox stays which are merely silver soldered in place.

John
Secretary of The National 2½" Gauge Association
Member of North West Liecestershire SME

http://www.modeng.johnbaguley.info
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