LBSC's Doris versus the Code

[jma1009]

hi brian,
one thing ive always done is to fix the front part of the foundation ring to the throatplate with suitable high melting point stuff before fixing to the barrel. this makes assembly of the rest of the boiler components much easier later on. my apologies as should have included this in my previous post. im not in favour of making all the parts and doing a 'dry' assembly as so much can change and slightly alter as construction progresses. avoid this temptation please, and just get on with the silver soldering! i also leave the flanged plates and inner and outer wrapper of firebox over length as advised by Ed, and trim much later on.
cheers,
julian

[runner42]

Hi Julian,

your advice came a little late as I already silver soldered the throat plate to the barrel. I have completed the silver soldering of the outer wrapper to the barrel, except for some rivets on the outside and all the rivets on the inside. The butt joint rivets however have been silver soldered both sides. The silver soldering on the inside was a PIA. The cosmetics is a little messy but I think it is sealed. If there is any rework required I am sure the boiler inspector will let me know.

Brian

[ejparrott]

I might be tempted to have another look at that top right corner when you do the dome bush or crown stays, but it might look better in real life anyway.

[runner42]

Hi Ed,

yes it looks a bit suss but it is OK. Sods law prevailed when I silver soldered to top two 9mm thick pieces, I didn't fix them in position because of the need to silver solder the rivets. Although at room temperature they seemed that they weren't going to move the LH one shifted slightly and what you see is the top corner had moved into the wrapper. Not good workmanship but it is best left alone.

Brian

[jackrae]

It looks as if the boiler strap solder hasn't flowed right through to the outer butt.

[runner42]

The process applied was to flux the butt strap and barrel before riveting, afterwards liberally flux the sides of the butt strap. Laid a 1.5mm rod of silver solder the length of the butt strap each side and applied the heat on the outside of the barrel until the silver solder ran to form penetration, which is evident at the ends of the butt strap and the join at the barrel. The gap is small in the places shown in the photograph but nevertheless it discernible.

Brian

[jma1009]

hi brian,
what you have done so far is extremely good and unfortunately our pics of these things dont show the 'full picture'! glad to hear all is ok on close examination, and look forward to seeing futher progress very soon! a taper barreled belpaire firebox isnt easy, and you are doing very well!
cheers,
julian

[runner42]

Thanks Julian,

tomorrow is the day that I get the boiler inspector to inspect my first silver soldering.

Whilst I am waiting for that inspection I decided to tackle the top feed arrangement for the axle pump and injector (let's hope the injector in the fullness of time provides an output). LBSC didn't provide detailed requirements for the piping so I studied others efforts from pictures on the internet and chose to have the chassis mounted pipe connections as close to the top feed assembly as possible. I obtained a casting from Blackgates which required a lot of filing to get the curved base as close to the profile of the boiler. Someday I must try machining instead of filing. This will have to be screw fixed to the boiler, so I will have to make a couple of blind bushes to achieve this iaw the code. However, what has caused me some angst is the curved forward facing in-feed pipes that pass through the boiler. How is this achieved to provide a steam tight connection? LBSC depended on the curved surface of the top feed assembly to be accurately machined to the profile of the boiler and screwed directly into the boiler. The code doesn't allow direct screwing into the boiler.

 

As young Hagley would say that I have been hoisted by my own petard, the in chassis connections were achieved by making them with the boiler removed and it being tapered slip the boiler in from the back. But with in in-feed pipes in place this can't be done so I will have to bend the pipes to the contour of the boiler after the top feed assembly has been assembled.

Brian

[jma1009]

hi brian,

i would scrap the top feed casting you have already made, and fit a 'T' piece screwed into a bush silver soldered on top of the barrel. union nuts and cones on the ends of the pipes can then be connected up to the 'T' piece. the whole lot can then be hidden by a hollow cover the shape of your casting (or you could mill out the casting to be a snug fit over the 'T' piece and pipes and their connections).

on the bottom of the 'T' piece where it screws into the bush you can if you want drill holes so that the feed comes out of the side rather than the bottom, or fit a removable and angled plate inside from the dome forward. personally i wouldnt bother with either.

hope this makes sense.

cheers,
julian

[runner42]

Hi Julian,

your alternative proposal for the top feed system seems to have advantages so I shall adopt it. However, so that I get some idea of the size what hole size/thread should I use for the bush to be silver soldered to the barrel and should the two feeds be kept separate or can they be combined in the T piece?

Brian.

[runner42]

Nov 4, 2014 9:15:29 GMT ejparrott said:

I might be tempted to have another look at that top right corner when you do the dome bush or crown stays, but it might look better in real life anyway.

I had the benefit of both boiler inspectors and they were unanimous in their opinions that a bit more solder is required at the place Ed indicated. They said it looks suspicious so it is best to do it at this stage so that leaks don't occur later on.

Brian

[jma1009]

hi brian,
it rather depends on how fine you want to make things and what out of. plus what size injector you propose fitting. depending on the above, and if the 'T' piece is made out of hard drawn phos bronze you could just get away with 1/40" x 40 tpi and a No. 30 or 27 drill as the passageways depending on injector size. otherwise go up to 5/16" x 32 tpi with a 5/32" dia pasageway.
i can assure you there is absolutely no need to keep the feeds separate.
cheers,
julian

[runner42]

Hi Julian,

back on the boiler. I noted your comments on the sequence of build of the boiler in the other post but I had to have the tubes and flues silver soldered to the firebox flange plate without the wrapper being attached. The reason being is that the firebox wrapper is small in comparison and although I have small hands I would have extreme difficulty in getting the silver solder rings in place. However when I come to silver solder the wrapper I shall apply a heat shunt to prevent overheating the outer tubes.

The picture shows my jury rigged method of setting the flues and tubes in position for soldering. It consist of two house bricks joined together with a piece of angle iron. The firebox tube plate is fixed with a G clamp. The height is just 3/16" too high for the correct positioning of the flues and tubes so a bit of scrap metal was placed at the bottom to raise the tubes and smoke box tube plate to the correct distance from the firebox tube plate. A square was placed against the flues and tubes to check that they are at right angles in the two planes.

The firebox tube plate was fluxed and the silver solder rings added.

Silver soldered and in the pickle.

I can say at this juncture that in two positions the silver solder didn't wick through, but thankfully on the outside tubes, so I will have to put a bit more silver solder on the water side of the firebox tube plate when I come to do the wrapper.

Brian  

PS Should you think that the tubes extend a little farther through the tube plate than is necessary, the boiler inspector requires that it be at least 5mm.

[ejparrott]

I've always set them to be about 1/16" through myself. When father built the Lion boiler in the 70's, the done thing apparently was to have them all but flush, as a result of which after 30 years of running one eventually gave up...followed by another after I'd plugged the first, before finally scrapping the boiler.

I fail to see the point of 5mm or projection, the fillet is never that big so it can't achieve anything. I'd like to see his science behind his demands.

[jma1009]

i agree with Ed. in fact i probably make mine in the firebox less than 1/16". but then i apply the silver solder via rings on the otherside plus a 'generous' 2-4 thou gap.

brian, you have done very well! and i dont envy you having to now do the inner firebox wrapper afterwards as this will be tricky - but at least at the same time you can rectify the odd tube you mention that needs a bit of extra silver solder. flux everything again before you do so though!

cheers,
julian

[runner42]

The code doesn't specify that the tubes and flues should extend past the tube plates by 5mm. However, those with a copy of the code at fig 4.1.1 Typical Boiler Construction shows the tubes extending past the tube plates by a reasonable amount. I think that the boiler inspector has quantified this to be 5mm being a generous amount so that tyros like me don't run into difficulty by having insufficient feed through and cause rejection of the boiler. But then again it could be for another reason.

Brian 

[steam4ian]

Brian

I (underline I, IMHO) would do the resoldering before you do the wrapper. You will have enough to do sorting that out without worrying about the tubes.

Ian

[runner42]

Hi Ian,

that's just what I have done. I was concerned that wicking through didn't occur on two tubes and wanted to understand the reason why. Well is was pretty self evident that the two tubes that didn't have wicking through were the two adjacent to the G-Clamp, not that it was taking heat from the area of interest, but that the paint started to burn off the G-Clamp so I aborted the soldering process a little early and the consequence was that that area didn't reach temperature. That was fixed by applying more flux and more silver solder to that area without the G-Clamp, the remaining tubes held the firebox tube plate in position.

Hi Julian,

what position of the firebox tube plate/wrapper configuration would you recommend, lying down or vertical?

Brian

[ejparrott]

I always do them vertical, tubes uppermost, you'll have to be careful not to get the tubes too hot so they fall through. I always bead the end of my tubes, but then I do tubes and wrapper at the same time anyway.

[jma1009]

hi brian,
as you know i put the tubes into the tubeplate after doing the inner wrapper to tubeplate joint.
you now have to bring the tubeplate up to heat with the tubes in it to do the wrapper, and you do not want the tubes moving through the tubeplate so i would keep the tubes horizontal, with the wrapper upside down so that the silver solder runs by gravity to form a nice fillet on the what will be the top curves of the wrapper. i should point out that your adding strip of silver solder and heating from the otherside is going to cause problems here and you really ought to add the silver solder once the job is up to heat, feeding it into the joint as you work around. and dont forget the rivet heads!
if you decide to follow Ed's method with the tubes pointing up vertically you must cut a piece of thermalite block to fit inside the wrapper tubeplate assembly to stop the tubes dropping down.
if you are going to silver solder the firebox side stays and tubeplate to throatplate stays (instead of threaded and nutted comsol stays) you will need to leave off the inner firebox doorplate on the inner wrapper.
cheers,
julian