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PGK's 1" Minnie

working through the book

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henryb12/11/2019 07:56:24
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43 forum posts
3 photos

I have used this thread as a reference a lot as well in the last year.

Jon Cameron12/11/2019 09:00:13
231 forum posts
87 photos

Julian, id like some clarification on a post on the previous page you say that you solder the foundation ring to the thoat plate first. I assume that this is before soldering the throat plate to the main barrel, or at the same time as soldering the barrel and throat plate? I guess it would serve a couple of useful points in that you will have a spacer to clamp to when you come to solder the inner Firebox, to the barrel and wrapper assembly. Also while soldering the barrel and throat plate first, the front part of the foundation ring would get pre warmed, meaning that a blast of the flame should see this heat through and the solder melt and flow.

So order of assembly would be (HT=High temp solder, LT=lower temp solder) numbered steps are cook ups, possibly could reduce these but where?

1.barrel and front throat plate, then onto the foundation ring front part. (HT)

2. Then outer firebox wrapper to barrel. (HT)

3. Inner Firebox wrapper to front firebox tubeplate (HT)

4 crown stays to firebox (HT)

5, tubes to front firebox tubeplate, rings of solder, use smokebox tubeplate to align tubes. (LT)

6. Inner assembly and outer riveted together clamping to front foundation ring, (foundation ring drilled and tapped for copper/bronze slot head screws?) and riveting the crown stays to The wrapper. (LT)

7. Front tube plate, and around tubes (LT)

8. Inner Firebox firedoor ring (HT)

9. Inner Firebox to rear Firebox wrapper (LT)

10. Foundation ring sides (LT)

11. Backhead bushes (LT)

12. Backhead, and rear foundation ring. (LT)

Just realised I missed the steam take off block from that assembly should be same time as step 2, screwed from below and then drilled though after cook up.

julian atkins12/11/2019 23:34:19
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1219 forum posts
353 photos

Hello Jon,

As you have taken the considerable trouble to quote me plus provide a detailed post, you deserve a detailed response...

Your:-

1. I do the front foundation ring to the throatplate first. I don't make the front and rear foundation ring out of square section copper but out of a slab of copper, which gets profiled further back and forward respectively around the inner and outer firebox wrappers with a step on the ends.

3. I tried this once with J-M silverflo 24 but the tubeplate got far too hot for my liking, and was stopped partly silver soldered, so the answer to your 3. is LT not HT.

4. LT J-M silverflo 55, not HT J-M silverflo 24.

6. No need for any fixings between front foundation ring and firebox tubeplate. Your 7. done at same time.

8. I do special phos bronze stays for the inner firebox doorplate to backhead at the same time in HT.

Between your 8. and 9. I silver solder up the firebox side stays, and do the foundation ring sides (your 10.) all LT. The throatplate stays have been silver soldered at your stage 6.

11. Backhead bushes are HT done before the backhead is silver soldered to the outer firebox etc as the final stage, the previous stage which was silver soldering the front smokebox tubeplate to the boiler, which would also have it's bushes done beforehand with HT.

I silver solder in the longitudinal stays. Dome bush is done early on in the the last 2 cases with HT. Safety valve bushes done the same time as silver soldering the crownstays to the outer firebox wrapper, LT.

I hope this makes sense. I did a detailed 'build log' of my last boiler on modeleng.proboards.com, and a lot of the pics of same are in some of my albums on here.

Cheers,

Julian

Edited By julian atkins on 12/11/2019 23:40:19

Edited By julian atkins on 12/11/2019 23:41:18

Jon Cameron13/11/2019 00:11:34
231 forum posts
87 photos

Julian,

Many thanks for your response, it wasn't planned as been detailed or to quote you, so appolagies if I've caused annoyance or offence. I simply wanted to try make a bullet point list for assembly of soldering.

After acquiring a scrap boiler for nothing that even after my inexperienced view is shoddy and dangerous, it's been lopped apart with an angle grinder and the front tubeplate cut off, and the barrel at the throat plate cut, which has left me with a nice section of 13SWG copper that is quite possibly going to get hammered soon. It's also left me with dozen 3/8" tubes, at around 7" length. So after a clean up an flattening, (flattering...dammit autocorrect, as if you could flatter a peice of copper that causes you so much frustration haha), I'll have a tube plate, and backhead that's 13SWG, and tubes which makes the cost of the boiler quite small by comparison.

After your response I have clear in my head which steps to take going forward, hopefully as does PKG should he attempt a third try at the boiler, or at least try to chase the leaks to satisfaction.

I do testament to another thread and this one where light weight insulation blocks from builders merchant, reflect heat a a fraction of the cost of commercial thermalite blocks. I soldered a thin gauge brass boiler (of mamod proportions) with plumbers flux and solder, using a small hand held torch filled with lighter gas. The solder ran beautifully after the tube was well packed around with offcuts of the blocks something that I thought would be impossible.

Again thanks for your contributions hopefully I may make a boiler in 1 attempt but then again pigs might fly.

pgk pgk14/11/2019 06:42:37
1486 forum posts
285 photos

Justin,

I'd appreciate your further comments, please

To shape the front foundation ring I guess you have to have the inner firebox assembled at least temporarily (or solder its wrappers first). Indeed it was the fiddly corners when my original leaks happened unless one manages a good fillet to smooth it out. Is there any benefit to adjusting the inner firebox to have it's wrapper inside the ends?

You suggest using a wider piece of copper to shape that front foundation ring (which makes sense). If curving that around the side of the inner firebox do you cut a step so the side foundation rings can also be stepped and sit on top?

pgk

julian atkins14/11/2019 21:42:45
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1219 forum posts
353 photos

Hi pgk,

Quite the contrary.

The front (and latter rear foundation) ring bits are milled and filed to fit the inner plates namely the inner firebox tubeplate, and inner firebox doorplate up to where the inner firebox wrapper starts and later ends. You dont have to have the inner firebox made up to do this for the front piece of the foundation ring, but you would have to hand the already flanged plates for the inner firebox to hand.

Obviously, to do this you need wider section copper first than the simple width of the water space.

Many boiler makers have problems doing the foundation ring sections, and to my mind anything that makes this easier and less fraught ought to be adopted.

I hope this makes sense. A simple sketch would probably make this a lot clearer.

Cheers,

Julian

julian atkins14/11/2019 21:42:47
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1219 forum posts
353 photos

Hi pgk,

Quite the contrary.

The front (and latter rear foundation) ring bits are milled and filed to fit the inner plates namely the inner firebox tubeplate, and inner firebox doorplate up to where the inner firebox wrapper starts and later ends. You dont have to have the inner firebox made up to do this for the front piece of the foundation ring, but you would have to hand the already flanged plates for the inner firebox to hand.

Obviously, to do this you need wider section copper first than the simple width of the water space.

Many boiler makers have problems doing the foundation ring sections, and to my mind anything that makes this easier and less fraught ought to be adopted.

I hope this makes sense. A simple sketch would probably make this a lot clearer.

Cheers,

Julian

pgk pgk14/11/2019 21:52:13
1486 forum posts
285 photos

Julian,

First I must apologise for the brain fart in calling you Justin! Sorry.

So you fit to the curve of the inner firebox tube plate and then later file the flats for the firebox wrapper once that is ready for fitting? Any benefit in my suggestion of curving it further round then having a step for the side piece of the foundation ring to sit on?

pgk

julian atkins14/11/2019 22:49:02
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1219 forum posts
353 photos

Hi pgk,

The front foundation ring section is milled and filled to be a jolly good fit between throatplate and inner firebox tubeplate, also as you note fitting the side curves of the inner firebox tubeplate, having determined where the inner firebox wrapper will be, to which it will end up abutting. The step on the ends is milled. It isn't a big step, but enough to intersect with a step on the foundation ring sides and avoid that problematic butt joint plus avoid the foundation ring sides moving latter on.

I make the flange depth quite generous.

Cheers,

Julian

pgk pgk15/11/2019 00:17:48
1486 forum posts
285 photos

Julian,

 

Excellent. Understood. Thanks

pgk

Edited By pgk pgk on 15/11/2019 00:18:21

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