Seeking info

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Sif-Bronze is best for Steel. But you can check if OK for the boiler to join copper, there's plenty of on-line advice about this. That's where I would need to look.
The REGULATIONS are for designs of boilers using SILVER SOLDERED copper . I know Sif-Bronze has some capillary action, but the silver solder is designed for the capillary action of filling a couple of thou gap between the 2 copper surfaces. That's where it gets its strength, not from fillets of solder.
I think the top reason for using silver solder on copper boilers, is the temperature of melt of the solder. SifBronze melts very close to the melting point of copper, although I have used it, but not on boiler work. I have also looked on the web at copper MIG brazing (uses SifBronze wire) or Copper welding (TIG). There is so little information about SifBronze brazing of copper that maybe it is just more risky from the higher temperature required to fuse to the copper?
I use silver solder 55% silver, as this is really easy to use. But if silver soldering in stages, where you need one stage to remain solid while the next stage is made, then you need to ring changes in the silver solder to give you a good range of assembly temperatures. Start High temp., on small sub-assemblies, and lower the melting point of solder at each stage. Needs some homework, research and planning.
Unlike welding, you have to heat a huge amount of the job while silver soldering, so it takes a BIG blowtorch and LOTS OF BRICK INSULATION, so you can get the joints hot (e.g. on shell ends). I bury 3/4 of my boilers in a bucket of sand for insulation, so only the end being worked on is exposed. But the sand must be DRY.
Using the highest melt-point silver solder on bushes, internal reinforcements, etc. is a good idea. Then the sub-assemblies can be assembled together for soldering with a lower melt silver solder. - I mentioned to someone that my boilers were worth more in "silver" than scrap copper! But a good boiler can last more than a lifetime!
PICKLE well between stages, and apply a paste of the flux powder (a drop of washing-up liquid with some powder) before assembly of the ends to cylinders. Lots of "teaching" videos on the web.
A few pics attached that I took to help someone else see what I do to make boilers. I use 3 Blowtorches, Lots of firebrick, Leather welder's gear, hand protection, etc, safety mask/goggles, boots and brain. - The last is most important.
You need to set-up properly, as when the job is hot, 3 lamps are roaring, and the flux has melted, you don't want to find you forgot something - like solder or tongs?! P2272319.JPGP2272320.JPGP2272321.JPGP2272322.JPGP2272323.JPG
P2272324.JPG

And please think to use TINS/metal containers for sand, etc., not plastic containers. (They burn well!).
DO NOT plunge the finished boiler into water, Many a crack has been created by dunking hot metal. BURY the finished job, so heat can dissipate slowly and not develop shrinkage stresses.
The finished boiler will be annealed copper, with the strength of hot toffee.. or wet cardboard... so handle with care when cold. And DO NOT DROP IT! it will buckle so easily... and then you have to start again!
When below 100degrees C (boiling water temp) lower into the pickle, to warm the pickle and encourage rapid dissolving of the flux and oxides. Wash well in water after pickling, before the next step.
OK?
K2
 
Last edited:
Cheers Ken, I've done quite a bit of welding over the years and have amassed a pretty comprehensive kit. most of my welding has been on steels and aluminium, can't ever remember lifting a torch to copper though.
I have a lovely little 200 amp TIG inverter plus an O/A portapac set, and a Saphire 5 torch with a full set of nozzles. I've also got a micro torch for the O/A as well but the No1 nozzle on the Saphire looks like it will cope, you can keep the hot spot pretty local. I think we'll stick to silver solder though.
We did some test/practice pieces with some copper off cuts but Edd took them home to show his dad.
Just been down the metal shop again and got some 0.9mm sheet offcuts for the tank, that should test him. !
Here's one of my previous project with quite a bit of welding on it.

Best regards sutty
 

Attachments

  • IMG_0528.JPG
    IMG_0528.JPG
    2.2 MB
With that level of skill, I should strongly consider TIG welding with copper wire as the filler. I think you need either pure Argon, or Argon-Helium mix? But there's plenty of advice on't web. I understand a 200A set is about as small as is practical for copper welding - it conducts heat away so rapidly. But should be good for up to 3mm or 1/8 in thick plates welded. All typical welded joints but shellsfor pressure vessels need seams with backing strips, and correct preps and gaps from tables. Fillet welds just good and larger than the adjoining sheets. But as a competent welder, you'lloyds know more than me!
K2
 
Ken, I use Argon for all my tig work, but I think it’ll cost me a fortune in tips letting Ed loose on the tig set Just yet.
i’ve got a half scale Morgan +4 half done that I’ll let him loose on when he’s got good at it.
 
Hi Sutty. I have been pondering buying a 20 A TIG set. I have only ever done stick welding (160A AC Transformer). But would only buy a TIG set if I found someone for advice for welding copper. TIG appears to be the most versatile system for almost everything for hobby work.
K2
 
ken mine is about 11 years old now and it’s really good, it’s got pulse, HF start, MMA, the missus bought me a foot pedal for it just after I got it and you really need one, especially for sheet stuff, the gas is pretty dear, around £65 for a refill plus bottle rental, but I have seen cheaper, where you buy the bottle so there’s no rental.
ive been looking at videos of using tig with silicon bronze without flux need to practice first Though. It’s like all welding, cleanliness is key to success.
regards sutty
 
Cheers Ken, I've done quite a bit of welding over the years and have amassed a pretty comprehensive kit. most of my welding has been on steels and aluminium, can't ever remember lifting a torch to copper though.
I have a lovely little 200 amp TIG inverter plus an O/A portapac set, and a Saphire 5 torch with a full set of nozzles. I've also got a micro torch for the O/A as well but the No1 nozzle on the Saphire looks like it will cope, you can keep the hot spot pretty local. I think we'll stick to silver solder though.
We did some test/practice pieces with some copper off cuts but Edd took them home to show his dad.
Just been down the metal shop again and got some 0.9mm sheet offcuts for the tank, that should test him. !
Here's one of my previous project with quite a bit of welding on it.

Best regards sutty
I would be quite curious as to how you made the rims for those tires - - - grin!

Looks very nice!
 
ajoeiam, the rims were made from 2" x 1" aluminium channel with the 1" legs cut down to 16 mm then i rolled them into rings and welded them, the centers were made from 4mm aluminium plate, dished then welded in to the rims.

regards sutty
 

Attachments

  • wheel.jpg
    wheel.jpg
    130 KB
  • IMG_0331.jpg
    IMG_0331.jpg
    201.1 KB
  • wheel 1.jpg
    wheel 1.jpg
    77.7 KB
  • wheel2.jpg
    wheel2.jpg
    255.8 KB
Hi Sutty. That (#86) is interesting. The only thing I can add is that although I have seen many silver soldered boilers, and a couple of copper welded boilers, I have never seen SifBonze brazed boilers... But that is just my experience?
I guess the argument goes... If you are brazing/soldering the silver solder route is very common, well understood and lower temperature than SifBronze brazing. Probably why it is the commonest route, and covered by ASME regulations. However, using TIG or MIG, then copper welding is probably better to long term corrosion than the mixed metals from SifBronze rods as filler, and copper wire for welding is cheaper than SifBronze rods (use clean, old, scrap electrical wire?). And there are no weird metallic interfaces to worry about for long-term corrosion., if that can happen... SifBronze temp typically melts around 875~900deg.C., and the melting point of copper, 1085deg.C. So I can see that the bronze brazing is similarly stable like silver soldering, just 150degrees hotter... and 200degrees cooler than welding? I really don't know the answers, but 95% sure it will work OK if that's your choice of filler rod? Better to consult a "proper man" than follow my advice on this one.
An example of a "proper man"...
https://www.maidstone-engineering.com/pages/custom-boilersAlso, all the texts of SifBronze say it's OK for joining copper... As long as it doesn't contain Zinc (which dissolves over time in Brass fittings - de-zincification - which is why Brass is ONLY used on "disposable" fittings, and NOT boiler bushes, etc.).
https://www.thomasnet.com/articles/...minum, zinc, lead, iron, manganese, and more.You should really check the actual grade of SifBronze from the data sheet to understand the Zinc content.
I does look like it is stronger than the copper you are joining, but harder and more brittle, so careful cooling after making joints is key to the stress relieving of the whole boiler. DO NOT Quench until below 200C.
Sorry I am not an expert able to give a definitive answer on this one?
Are you a member of a Model Engineering club? - They may have or know an expert? (Or maybe just a bunch of "fiddlers and meddlers" - like me?). Remember: "Expert" = "EX" = "Has been" and "Spurt" = "Result of a failure under pressure".. so watch out for self-confessed "Experts" (like me?).
N.B. The car is a Big WOW! - The driver - brilliant! - Well done on "making both!"
K2
 
Hi Sutty. That is interesting. The only thing I can add is that although I have seen many silver soldered boilers, and a couple of copper welded boilers, I have never seen SifBonze brazed boilers... But that is just my experience?
I guess the argument goes... If you are brazing/soldering the silver solder route is very common, well understood and lower temperature than Sif Bronze brazing. Probably why it is the commonest route, and covered by ASME regulations. However, using TIG or MIG, then copper welding is probably better to long term corrosion than the mixed metals from SifBronze rods as filler, and copper wire for welding is cheaper than SifBronze rods (use clean old scrap electrical wire). And there are no weird metallic interfaces to worry about for long-term corrosion., if that can happen... SifBronze temp typically melts around 875~900deg.C., and the melting point of copper, 1085deg.C. So I can see that the bronze brazing is similary stable like silver soldering, just 150degrees hotter... and 200degrees cooler than welding? I really don't know the answers, but 95% sure it will work OK if that's your choice of filler rod? Better to consult a "proper man" than follow my advice on this one.
An example of a "proper man"...
https://www.maidstone-engineering.com/pages/custom-boilersSorry,
K2
 
Ken, got a nearly full tub of sil bronze but I think Edd will find silver soldering better and save the silicon for use on steel.
brazing with O/A is good practice for filler feeding which is key to getting neat tig welds plus with with gas you can control the wetting out. When I can I’ll have a go at tig welding copper.
the driver in the vid is the grandaughter, Ed’s sister. When Ed was little he was mad on Disneys film Cars, and one particular car was a Wilys jeep called Sarge so I decided to build him one, that turned into a mission too !
then when the little one arrived I had to build a car for her.
The decision to build the Bug came about at a drunken weekend at Prescott , which is home of the Bugatti owners club hill climb, my mate and me had walk around the museum there an we were looking at a type 51 which Etore Bugatti made for one of his children, i was saying to my friend about making one and was over heard by the curator who must have picked up on my broad Brummie accent giving the impression that we’re thick, he told me that I had no idea what was involved in building one! Red rag to a bull set me off on another mission.

regards sutty
 
Hi Sutty. That is interesting. The only thing I can add is that although I have seen many silver soldered boilers, and a couple of copper welded boilers, I have never seen SifBonze brazed boilers... But that is just my experience?
I guess the argument goes... If you are brazing/soldering the silver solder route is very common, well understood and lower temperature than Sif Bronze brazing. Probably why it is the commonest route, and covered by ASME regulations. However, using TIG or MIG, then copper welding is probably better to long term corrosion than the mixed metals from SifBronze rods as filler, and copper wire for welding is cheaper than SifBronze rods (use clean old scrap electrical wire). And there are no weird metallic interfaces to worry about for long-term corrosion., if that can happen... SifBronze temp typically melts around 875~900deg.C., and the melting point of copper, 1085deg.C. So I can see that the bronze brazing is similary stable like silver soldering, just 150degrees hotter... and 200degrees cooler than welding? I really don't know the answers, but 95% sure it will work OK if that's your choice of filler rod? Better to consult a "proper man" than follow my advice on this one.
An example of a "proper man"...
https://www.maidstone-engineering.com/pages/custom-boilersSorry,
K2
Normally I would use an Ar / He mix on copper and please use a correct filler wire for any copper welding more so for a boiler, as for boilers to be run in public you should have a boiler cert, and normally have to give the spec, on all materials used in the construction including filler wire
Paul
 
Thanks Paul! You are right. Good advice. I was wrong to quote using electrical copper wire of unknown heritage, although this is usually 99% pure copper.
Sorry If I misled anyone.
Sutty, is the "Red rag to a bull" quote alluding to the "Bull" being a symbol of someone from "Brumigham"?
K2
 
Thanks Paul, we'll be sticking to Silver Solder for this project. I want t o teach him the right way from the start.

Best regards sutty
 
Ken ,no. I'm one of those guys that love a challenge, and him saying that fired me up.

Regards sutty
 
ajoeiam, the rims were made from 2" x 1" aluminium channel with the 1" legs cut down to 16 mm then i rolled them into rings and welded them, the centers were made from 4mm aluminium plate, dished then welded in to the rims.

regards sutty

Very interesting!!!!!!!!!!

At the risk of being accused of never ending questions (sorry gotta grin at that!) - - - - your roller - - - your design - - - ideas - - -sketches - - - a url or some connection on the process - - - please?
(So many ideas and just so little time to get things done.
Making my own rims means that I could easily use motorcycle tires - - - or maybe even quad tires rather cheaply in projects like a cart pusher.)
 
A, not really my design but easy enough to copy, I wanted a ring roller where all 3 rolls were driven this paternoster system solved that.
The centre roll is on the carriage that moves up and down to bend the rad between the fixed rolls and carries an idler roller for the drive chain so the tension is constant, the 3 shafts are all 25mm. works ok.

Best regards sutty
 

Attachments

  • DSC_0256.JPG
    DSC_0256.JPG
    890.7 KB
  • DSC_0257.JPG
    DSC_0257.JPG
    1 MB
A, not really my design but easy enough to copy, I wanted a ring roller where all 3 rolls were driven this paternoster system solved that.
The centre roll is on the carriage that moves up and down to bend the rad between the fixed rolls and carries an idler roller for the drive chain so the tension is constant, the 3 shafts are all 25mm. works ok.

Best regards sutty
Thank you for your generosity - - sir!!

Looks good!

(Only one problem - - - - I just got myself another project - - - argh - - - that list just keeps expanding!!!!!!!!! (LOL))
 
hello guys, just had a dabble TIG welding some copper, the pieces were bright but not prepared, DCEN, the tip was a 2.4 thoriated, No5 ceramic, 20cfm Argon, max 90 amps. the filler was a piece shaved of the parent strip. The first two pix are a lap joint of 1.5mm thick the second two are a lap joint 0.9mm. front and back. the blow hole is me trying some silicon bronze but not sure of the rods cus i've had em that long the label has faded.
probably get better results with a pristine set up.

Best regards sutty
 

Attachments

  • 0.9 front.jpg
    0.9 front.jpg
    97.2 KB
  • 0.9.jpg
    0.9.jpg
    122.6 KB
  • 1.5.jpg
    1.5.jpg
    61.5 KB
  • 1.5 back.jpg
    1.5 back.jpg
    112.3 KB

Latest posts

Back
Top