Boiler Build order

[dfh]

Hi I am just starting to put together the boiler for a 5" Royal Scot and I am looking for advice on which order to put a few parts together.
Firebox tubeplate, tubes and wrapper, I have seen in a couple of books and on the internet, different ways, that is
1 tubeplate to wrapper then the tubes after,
2 tubes into the tubeplate and then the wrapper or
3 tubes, tubeplate and wrapper all in one go.

Any advice would be very welcome

David

[runner42]

I am no expert but for my Doris boiler I am going to silver solder the tubes to the firebox tubeplate (your option 2) and then the firebox wrapper. The reason is that to ease the soldering I am going to make silver solder rings the size of the tubes and flues and place then on the inboard side of the firebox tubeplate, with the firebox tubeplate horizontal and supported on a stand with the tubes facing down and at the other end the smokebox tubeplate used to keep the tubes and flues parallel and vertical.

Brian

[ejparrott]

I put the tubes in to the firebox tubeplate and fit the tubeplate to the inner wrapper at the same time. I use bronze screws to hold the tubeplate to the wrapper, and I support it with a specially made clamp with the tubes vertical in the front tubeplate, firebox at the bottom, then I can silver solder the tube ends from inside and the joint to the wrapper. I roll the ends of my tubes so they don't drop through the tubeplate. Make rings of solder to fit round the tubes.

I fit my barrel to the throatplate and the outer wrapper in the same way but the other way up, firebox at the top. I can solder the barrel flange joint from the inside, and if the fit is right, you can do the throatplate to wrapper joint too. If this joint has any suspect areas afterwards, it can be touched up when you do the stays. Don't usually have a problem with it though.

[jma1009]

i would certainly NOT go for option 2! the extra mass of the wrapper plus fitting it to the tubeplate requires a lot of heat and concentration, and there is the risk of burning the outer tubes if already silver soldered to the tubeplate. i have always used option 1.
ed's preference for option 3 is a better option than option 2 but is quite a lot to do all in one go on a big 5"g boiler, and not for the tyro.
cheers,
julian

[dfh]

Thanks guys for your suggestions, all very helpful, think I will probably do the tubes into the tubeplate first.
Thanks
David

[Shawki Shlemon]

There are few builds on this forum you can see , there is no wrong or right way , the important thing in my opinion is not to do too much at a step , I do the tubes / tube plate and inner wrapper as one unit , the barrel / throat plate/ front foundation and outer wrapper as one unit . Then I fit dome bush and other bushes that are far from joints and stays .From this point onwards there are different ways to handle the issue to suit your desire .

[runner42]

Nov 8, 2014 5:30:04 GMT runner42 said:

I am no expert but for my Doris boiler I am going to silver solder the tubes to the firebox tube plate (your option 2) and then the firebox wrapper. The reason is that to ease the soldering I am going to make silver solder rings the size of the tubes and flues and place then on the inboard side of the firebox tube plate, with the firebox tube plate horizontal and supported on a stand with the tubes facing down and at the other end the smokebox tube plate used to keep the tubes and flues parallel and vertical.

Brian

Just revisiting this so that I can provide an update. I said that I am no expert, that was re-enforced on the day that I tried to silver solder the wrapper to the tubes/flues/firebox tube plate, but after that event I am a little more experienced. As stated by Julian, Ed and Paul is not to go for option 2 and I am painfully aware that this advice is spot on. The wrapper and firebox tube plate should be silver soldered before the tubes/flues are silver soldered to the firebox tube plate. It's axiomatic that a flanged tube plate that is riveted and silver soldered to the wrapper when reheated is not going to move, but tubes/flues  silver soldered to the firebox tube plate when reheated can easily move.

In my situation I tried to silver solder the wrapper to the tubes/flues/firebox tube plate assembly, the wrapper lying down with firebox opening uppermost and apply the silver solder on the inside of the wrapper. Doris' firebox is quite narrow but deep and it was difficult with a full length silver solder rod to get near enough to solder the inside particularly the sides that come from the top of the firebox to the waisted section. The heat was too intense. An aside I viewed, after this incident, a boiler construction presentation given by a member of SASMEE and the first thing on his checklist was to have suitable protective clothing, I had bare arms T shirt and shorts.  I aborted this and stood the assembly vertically with the wrapper facing down. Although the assembly appeared stable when everything was at soldering temperature the lot fell over. Consequently, two flues were bent and many of the tubes were bent and the lot looked more like a bunch of flower stalks thrust haphazardly into a vase. I've de-soldered all the flues and tubes and straightened them and completed the silver soldering of the wrapper to the firebox tube plate and next the re-solder the tubes/flues. OPTION 1.

Brian  

[dfh]

Brian thanks for update, sorry to hear about your mishap, I also have learnt about the clothing the hard way, when the zip on the rh side of coat coat I was wearing burnt my wrist when it touched it.
I have started on my boiler and went with option 1, so far I have the tubeplate in the firebox wrapper and the main boiler tube into the throat plate. don't know what you used but I used a high melting temp s/solder for the first stages I have down to try and prevent mishaps later. Next will be tubes into firebox and wrapper to throatplate. I have been wondering whether to put 3 sides of the foundation ring on to the firebox wrapper with the high temp s/solder and just leave the piece that goes at the bottom of the backhead to do later.
Not sure what you are using but I certainly don't think I could have used the high temp rods without the use of oxy/acet with the propane. I am fitting girder stays on the firebox top, so I intend to use those to fasten the f/box to a piece of box section at the top and the tubes pointing down. My mishap was when I took what I had done to club night for boiler inspector to see and getting back home in dark and heavy rain open the tailgate and 6" piece of tube with throatplate on rolled out onto concrete drive. Now have to straighten flange to get the wrapper to fit.

David

[Deleted]

If you can get hold of a copy of Alec farmer's book on Model Boiler Making it is very well illustrated and gives you a step-by-step guide to the whole process.............Remember that as your boiler begins to take shape so too does the TOTAL mass of copper involved for any re-heating and manoeuvring.... www.slightlybetterbooks.com/alecfarmer.html

[dfh]

Hi Guys,
Just trying to sort out the holes in the backhead and believe I have read somewhere on here that the water feed into the boiler should be as high as possible. The drawing shows them going in below the bottom of the fire hole, what does anyone think, should I try and get them higher. Does it make any difference if the water is coming from injectors or from axle pump.

Also whats the preference, one water gauge or two, 3 valve or just plain with a drain cock?
Thinking about it, I guess there is no point in having 2 level gauges if they are not 3 valve type as if a glass gets broken thats the end of that steaming session whereas if they are 3 valve types one can be shutdown

David

[ejparrott]

Ideally the water needs to be into the boiler as far forward as possible. If fed in via the backhead then tubes can be installed inside the boiler to carry it forward. The height for me makes little difference. Most of my are fed in roughly on the boiler centreline or a touch below where there are saddle tanks.

Gauges are a bit of a compromise with the available space. For me, again, 2 gauges, and both 3-cock type. Some smaller engines it is all but impossible to achieve this. My 2.5" has only one gauge, and it only has a blowdown. There isn't room for anything else.