DAVID POWELL 4 | 12/02/2012 22:09:12 |
26 forum posts | I am making the boiler for the Juliet loco. It requires some of the copper pipes to be brazed.
How do you braze copper pipes? |
mgj | 12/02/2012 23:08:48 |
1017 forum posts 14 photos | With silver solder these days. If you are just starting out like that, I fear there isn't enough space on this forum to give you a good compete answer, but everyone has to start somewhere. . Strongly recommend Tubal Cains Soldering and Brazing, and Alec Farmers Book - Model Loco Boilers.(or similar, but Alec Farmer is the author.) Might also be a good idea to go down to the local club and ask those who have doen it before. It isn't difficult, but you do just need to have it properly worked out, with access to the right kit, to avoid disappointment and/or very expensive mistakes. |
Dusty | 13/02/2012 15:55:46 |
498 forum posts 9 photos | I agree 100% with mgj, join your local Club, the members will welcome you and provide advice and encouragement, they sometimes have the kit available for members use. Hopefully you will find someone who will stand on your shoulder while you make your first few joints and offer advice.
Making a mistake with kit if you are buying can be expensive, neither copper or silver solder are cheap these days and a few pounds spent on the books recommended will be an investment, or better still see if your local library can get them, you will probably be the only person wanting them and as such you will have almost sole access to them.
Don't expect perfect joints first time, only practice makes perfect. |
DAVID POWELL 4 | 13/02/2012 19:49:12 |
26 forum posts | Thanks for the advice on the books.......Will be collecting Tubal Cains' book from the library tomorrow.
The boiler is 80% complete all silver soldered as per instructions. However there are 2 copper pipes that need connecting to a 'made bend' which is quite acute, hence the need to make it I guess.
Here the instructions and the plans show them as being brazed together not silver soldered. As this design is about 60 years old perhaps using today's silver solder may be OK (has it changed in 60 years).
So I was just wondering how brazing copper is achieved. Clean the parts OK, apply flux....what flux? then heat up and use a rod of some description to bond the 2 parts together.
So what flux and what rod?
Would silver soldering would be a more than acceptable solution?
|
Dusty | 13/02/2012 20:12:35 |
498 forum posts 9 photos | If we start using the correct term of 'silver brazing' then things might start to become clearer. I suspect that you may well have realized that there are several grades of 'silver brazing' rod available. Silver solder has not changed much in the last 60yrs save that cadmium bearing rods are now banned exept for certain processes. I would use easyflow, or rather its modern equivilent which I think is silverflow 55. I have not indulged in any 'silver brazing' since the change but I am sure someone out there has, and can help. |
John Baguley | 13/02/2012 20:40:01 |
![]() 517 forum posts 57 photos | Hi David, Is it for the superheater by any chance? i.e. the joints between the superheater tubes and the 'spearhead' inside the boiler flue. In the 'old days' such connections would have been brazed using brass spelter as that would withstand the very high temperatures in that region. I would use a modern silver solder such as Silverflo 24 or Cup Alloys 824 along with a high temperature flux such as Tenacity 4A or the Cup Alloys equivalent. I use this combination for stainless steel superheaters that extend into the firebox and and they often glow red hot! Any connections inside the smokebox can be done with Easyflo (if you've still got some) or Silverflo55 as the temperatures are much lower. John |
fizzy | 13/02/2012 21:31:16 |
![]() 1860 forum posts 121 photos | I built one of these last year but I made a simple T joint as the one on drawings seems way too tricky! Mine ran fine. |
mgj | 13/02/2012 22:54:51 |
1017 forum posts 14 photos | Well one thing is for sure, is that you don't want to go using brass spelter inside a boiler.I think the risks of dezincification have been very much overstated, but even so, in a joint subjected to HP steam for some time, it would be unwise. Which leaves you with what we all know as silver solder. - whether its brazing or soldering is a matter of semantics (other than brazing tends to use brass and the rest of the world talks about silver soldering?) - its the temperature range and suitablitiy of the alloys which matters.Any of the silver based eutectics recommended above will be fine. If this component actually sees the firebox temperatures, then you'll need the high temp alloys.(though I'd prefer to weld) Otherwise the 620C stuff will be fine. I have used 55. i've heard people say it doesn't flow so well. Can't say I have noticed much difference personally. More expensive though. Might buy some CD bearing stuff claiming its for electrical connections if it comes to it. Its still legit for that I understand. |
DAVID POWELL 4 | 14/02/2012 08:19:13 |
26 forum posts | Thanks John Baguley, answer is spot on and I shall follow your recommendation. Nigel Jones 2 too (sounds wrong but is grammatically correct?) has a very useful idea so thanks for that. MGJ makes the point about dezincification. I was aware of this which was another reason why I posed the original question as this loco is an LBSC, a guru amongst model makers. Did he get it wrong? Was dezincifiction known in his time?
As for the semantics, I think Dusty has a point. The trouble is whose definition do we follow. Brazing is defined as ‘solder with an alloy of brass or zinc’ so if I use a ‘silver solder rod’ is that brazing? But there again isn’t brazing a French word and translated means soldering. So silver soldering and silver brazing means the same thing?
Anyway I need to Hoover the shed, no, I’m going to Electrolux it, on second thoughts I’ll just vacuum it. |
Tel | 14/02/2012 09:39:53 |
![]() 157 forum posts 28 photos | Might be safer just to run a broom over it! |
V8Eng | 14/02/2012 20:06:48 |
1826 forum posts 1 photos | Hi.
One of the last jobs I worked on while in full time employment involved installing refrigeration pipework, the joints were made using what was described as copper brazing rod, that was (I think) a copper phosporous material and did not need a seperate flux.
This was excellent for running into capillary joints, but I found it slightly less easy to use on flat or curved surfaces (might just have been me of course).
The finished product had all the appearance of copper, but I know nothing about its properties or suitability for any other application, it was also a long time ago!
Regards.
Edited By V8Eng on 14/02/2012 20:08:43 |
mgj | 14/02/2012 20:23:37 |
1017 forum posts 14 photos | V8 - that is a very dangerous route where boilers are concerned. Its a well known technique, and very good in its place, but somehere in the presence of sulphur is not one of them. It becomes very brittle, and is useless for our purposes, in our environment. Avoid like the plague in boilers using coal as a fuel. Dezincification - thats why I feel it has been somewhat overstated as a risk, but its best avoided, at least in the structure of a boiler where an item can't be replaced easily. Fittings, I think brass is fine. For my money, if after many years something goes brittle, you just take it out and change it. |
Russell Eberhardt | 14/02/2012 20:50:42 |
![]() 2785 forum posts 87 photos | Posted by DAVID POWELL 4 on 14/02/2012 08:19:13: But there again isn’t brazing a French word and translated means soldering. So silver soldering and silver brazing means the same thing? Not quite: French "Brasage" = Brazing. What is confusing over here in France is that "Soudage" can mean either soldering or welding. Best not to confuse those. Russell. |
Stub Mandrel | 14/02/2012 21:27:40 |
![]() 4318 forum posts 291 photos 1 articles | I understand that if you have some brass rod and enough heat, you should be able to use this to braze a superheater spearhead using borax (I got mine from a pound shop) as a flux. I also note that many people including (later) LBSC suggest using a copper block drilled at an angle for the two pipes as easier to braze and more reliable than simply trying to join the free ends of two pipes. Update: I'v just cut a short ring of 15mm copper pipe, split it and overlapped the ends. I used borax mixed with a bit a bit of spit as flux and 1/16" brass rod of unknown provenance. It took a lot of heat - bright red - and I half expected the copper to collapse but eventually the brass flowed and made a very sound joint. I would practice a few times first if you choose to go this way. Neil Edited By Stub Mandrel on 14/02/2012 21:42:22 |
V8Eng | 14/02/2012 21:42:15 |
1826 forum posts 1 photos | mgj.
Thanks for the information, I've not built a boiler yet, but will certainly bear it all in mind for future reference.
Edited By V8Eng on 14/02/2012 21:58:10 |
Ian S C | 15/02/2012 10:06:19 |
![]() 7468 forum posts 230 photos | I use brass and borax for brazing on my hot air engines, mainly joining steel. Ian S C |
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