Brit Progress: Boiler Plates

[brozier]

Removing the barrel seems a bit drastic, if it is roughly in the right position.

Remember the cleading will cover any minor imperfections.

If it were me starting from scratch I would have double flanged the throat plate



In your position I would make up an internal strap to cover the joint around the full circumference, flanging as appropriate.

An incomplete description of my boilermaking starts here :

homepage.ntlworld.com/bryan.rozier/Spencer/boiler_making/Boiler_Making.html

Hopefully of some use.

Cheers
Bryan

[Deleted]

Thanks to all for your support at this moment of need......
Unfortunately, I will have to hack it off and redo the joint. On the question of boiler design and manufacture, I can only quote the great man himself:

"..the brazing is the only means of holding the joint. This is no detriment, as the brazed joint is stronger than the metal of the boiler. We can't fit a 'piston ring joint', owing to the shape of the throatplate, but the four longitudinal stays in the boiler would prevent the parting of even a badly brazed joint".

I couldn't do a piston joint anyway, because the throat plate hole is about 1/8" smaller than the inside dia. of the boiler. If it were any bigger there wouldn't be any throatplate thickness at the top edge as the boiler barrel sits flush with the wrapper.

If I put a circumferential ring outside the boiler, it would spoil the exterior contours and look nothing like the original.

I could make a tapered elongated stepped ring as suggested, but I'm a fitter/machinist, not a miracle working tin-basher!
Looks like I'm stuffed.......

[Shawki Shlemon]

Hi JB
When I asked the question about the throat plate , I was concerned with the joint between the plate and the barrel and I had a picture very similar to that of broZier to show you as I am in process of building a boiler but your boiler inspector response stopped me . I can't put it here as there is no attachment on general chat. It takes one , may be two days to make and it is not hard to do , I am not a sheet metal worker either and if I can do it anybody can . I make all the formers from custom wood 3/4" thick . first cut a hole 1/4 " larger than the diameter of the barrel in a piece of wood ( make two ) and radius the edge on one . cut the piece of copper ( leave it larger than needed and trim later )and cut a hole in it 3/4" smaller than the barrel .
Make a die the same size as the barrel from wood , anneal the Copper ,hold between the two former with radius-ed side next to the copper and start bashing it in ( I use wooden mallet ) , repeat the process as it hardens until you are close then anneal again and force in the die, a little adjustment here and there and that part is done . Now form the outside flange as you did before , the only trick is to centre the die on your former and everything will fall in place .

[Deleted]

Hi Shawki, thanks for that. I think I ought to clarify the inspector comments in case I/he get into trouble! I told him I was making it to the words and music, and he gave me some advice about the droop and a few other tips. He didn't say that I'd have to deviate from the published design at all, so in my positive way of looking at things, I didn't see any negatives! I have contacted him this morning to clarify matters.
JB
EDIT: Thinking about your method I would use exactly that if I didn't have a bent throatplate. I would have to flange this one in the centre and edges, cut it, bend it and rework the flange to fit the tapered barrel. I can't quite picture it but I think the effective diameter of the lower part of the extruded flange would be smaller ('cos it's now an ellipse) than the upper. So I'm still stuffed!

Anyway, I'm going to talk to my next door neighbour who is a coded welder and get the thing brazed up!

[drjohn]

Helen Verrall makes exceedingly good boilers

DJ

[Deleted]

Hi DJ, nice to see you living up to my expectations!

[chris vine]

Hi JB,

Apart from knowing next to nothing about making boilers:

I think you will find it best (certainly more controllable) to cut it off carefully. The 1/32 you lose in the cut is nothing to worry about.

Can you then make a copper ring which is a snug fit inside the barrel which sticks out aft by about 1/8 to 1/4". This would then slide into the hole in the throat plate and hold everything in place when you solder it again.

Only a thought. Just don't fret, do something positive and something good will come of it!!!

Chris

[drjohn]

I wasn't being facetious JB. Tackling a boiler like that one as a first attempt on your own without a second pair of experienced hands is really ambitious and it might be cutting your losses to "cheat".

With your fastidiousness, it will always irk you that maybe it could have been better - just an observation.

DJ

[Deleted]

Point taken DJ, but I'll still have a go! Besides, have you seen the price of copper?!£!
JB

[Deleted]

I was given this suspension idea by a forum member so I tried it out this morning. A Royal Engineer type lifting frame, some 1/8" rod and a piece of steel jammed in the barrel. Firebox base is 1/8" off the bricks.

Dropped apart after about four minutes heat. Thanks Chris (Redmog), I owe you one! BTW those cheapo bricks are pretty damn good!

[redmog]

Next Best Approach?

Well Done JB.
A method of affixing before any silver soldering is now to be sort!
Any ideas?

Chris

[simonwass]

Nice to see you've separated it Got to file off that expensive silversolder now
Just a thought to save it moving next time, I know you've put your barrel butt strip on the inside, make up a small angled strip and rivet it to the throatplate on the outside (it wouldn't matter if it were on the inside riveted to the barrel as it wouldn't hinder circulation if kept small) and the barrel if you like, it'll stop the barrel moving down the slope and is out of the way once the boiler is finished. Gravity isn't useful for something you can't grab hold of if anything goes wrong If I were doing it, I'd have put the strip on the outside and make it longer to bend to go around the corner onto the throatplate.
I presume the Brit doesn't have any lagging?
As DJ says, a Brit boiler is ambitious for a 1st attempt but a boiler's a boiler
Problem with this one is the designer, it ought to be updated which would make it stronger and easier to build.

[Deleted]

Spoke with BOTH of our boiler inspectors today. Unanimous response was something like:
"It's an established design which wouldn't be approved today, but you go ahead and make it and there won't be a problem. If you personally are not happy with the throat plate then you could do this.....etc.!

So I will go ahead and make it! However, there is no lagging therefore exterior excrescences to assist matters cannot be easily concealed. I might just make a sleeve to fit in the lower half of the barrel and enlarge the throatplate hole to accommodate it.
JB

[Shawki Shlemon]

This is the basic difference between the UK system and ours in OZ , here if the the plans do not meet the code requirements then they must be modified to do so .However the latest code requirements are not retrospective for already build boilers. We don't accept such thing as published design unless it meets the code requirements . The builder is free to change the design to meet the code standard.

[Deleted]

Boiler barrel cleaned up and refitted. The assembly had distorted following the separation, so it was another precision filing job to get it to fit properly. There's a two thou gap all the way round, just on the outside rim. The interior gap is less! What a piglet! I drew chinagraph lines on the barrel to check with a roofing square that the orientation was correct.

I hope you can see that the top of the barrel is flush with the wrapper, which means that the throatplate has to be machined or filed back quite a bit to present a flat surface for the silver solder. I have seen other Brits where the barrel is much lower, perhaps to make life easier, but what the hell! Let's get it right! Let's hope it doesn't move this time when I solder it....
JB

[drjohn]

Sheesh, JB - looks pretty, but if that's an edge to edge butt joint like it looks - no-way Josay! A big bang in the making.

DJ.

[Shawki Shlemon]

Hi Dj
I presume that JB will fit stays at the bottom part of the throat plate , the rest of it is not subjected to high forces , even though there is 100 psi pressure but the area is relatively small compared to tube plate and back plate and therefore the only problems I see is possible leaks if not done 100% right . this type of joint is not acceptable here and we don't do it , however if it is acceptable in UK the builder has the option .

[brozier]

Can you add a few small intenal brackets with rivets to physically hold the barrel in place?

I had 4 rivets holding my barrel to the throat plate.

I think there is so much heat expansion going on you need some kind of fixing to hold things together....

Worked well on the throat to wrapper joint...

Regards
Bryan

[Deleted]

Hi Bryan. As you suggest, I was going to rivet four internal 1/4" wide lugs onto the barrel end, and fit them into four corresponding slots accurately filed in the throatplate aperture, where there is 1/8" of 'meat'. That will give me a positive location when the barrel is positioned vertically, and also provide a staying function to supplement the design discrepancies.
Unless someone has a better idea that is.......
JB

[drjohn]

JB I did tell you that Helen Verral makes exceedingly good boilers.

Albeit your throat plate is slanted, but with your ingenuity, you could make a joining ring and then be able to sleep nights.



DJ