Copper Boilers - the future

[steam4ian]

G'day all

At a club meeting, Tuesday, some bloke was expounding that copper boilers have no future. Hi reason, cadmium free silver solders will not flow.
What is the experience of my learned friends?
Has anybody built a boiler with cadmium free silver solder?
What tricks, fluxes etc did they use to get a good result?

Regards
Ian

[AndrewP]

Initial response was cob***rs but then after some thought I decided b**l**s was more appropriate.

I've got an admittedly half finished boiler here using only cadmium free silver solder and use the stuff every day - it flows just fine. On small stuff I use a flouride based liquid flux but on copper prefer Tenacity 125 - it lasts longer than Easy flo.

I suspect most silversmiths are using the cadmium free solders nowadays since it has suddenly become bad for us to sniff it up our noses - used to be just fine, must be some new style bad cadmium

[chris vine]

Hi Ian,

Except for soldering brass (where I use easyflo 2 because it is a bit lower temp) I use silverflo 55. It is lovely stuff and I would say flows better than easyflo. Rally it runs like water when it goes. I believe silverflo is cadmium free.

It is a few degrees hotter than easyflo 2 and so you have to be mighty careful on brass, but I think that with copper it would be fine.

Have not built a boiler with it though....

Chris.
PS 200 hp motor has only 3 wires and on the plate there is a voltage and current rating for st but the rt is blank. I guess st is stator and rt is rotor. So it seems that it is a simple induction machine with no slip rings etc...?? C

[steamjohn248]

Talk to Trevor at SWINDON BOILERS, what he does'nt know about building copper boilers could be written blah blah blah.

A satisfied customer.

John

[baggo]

Hi Ian,

I think your bloke is, putting it politely, talking out of his bottom

I've built four boilers over the last couple of years using cadmium free silver solders with no problems whatsoever. No special techniques or magic fluxes. I do still use Easyflo for fabrications and the final soldering ops on a boiler such as stays but I've no doubt the cadmium free version will be just as good.

The only thing that's going to finish copper boilers is the ever increasing price of the materials

John

[ausdan]

It was circulated at the annual AMSBC meeting at the convention, that some concern maybe needed. I asked the question on the coals email group, here is the response:

Hello Danny, and anyone else interested,
There was a short informative talk given by Dave Giles, a visitor from NZ. He outlined some potential problems using cadmium-free silver solder on copper boilers, and particularly bronzes used for boiler fittings. It seems to resist good penetration. The outcome from the discussion was that cadmium bearing solders are probably a lot easier for amateurs to use, but that they should be aware of the potential health hazards which may arise from its use. Cadmium bearing solders are apparently getting hard to buy, as retailers become wary of backlash for selling it, so a couple of people are going to look into sources of supply, with a view to (perhaps!) AMBSC buying it in significant quantities, for onselling to modelbuilders. If this should happen, it will be bought at the best possible price, and passed on to bonafide modellers at a similar price, allowing for packaging and postage.
This may take a while, so if you are in a hurry, do your best, but if you end up buying cadmium-free solder, may I suggest you practice with it before attacking a lot of expensive copper!
Regards, Ian Kirby.
Chairman, AMBSC.

So with that in hand, knowing ive got 2 boilers I plan to build, I ordered a kg of cadiuim 45% silver solder, the shop needed to order it and hopefully I'm expecting a phone call today

Dave Giles pretty well is a major playing in the New Zealand model engineering scene and runs his own business building engines of small gauges and up
www.ikoneng.com/trains.htm

[GWRdriver]

We have a fellow over here who I'm sure is a fine person, and whose work indicates that he is a first-rate amatuer machinist and loco model builder, but he preaches at every opportunity that the wetting and flow characteristics of Cad-bearing solder are superior in every way to non Cad-bearing to the extent that it is futile to attempt to use it on a model boiler. To that I have politely replied, in an open forum, . . . . RUBBISH!

[stantheman]

The opening of this thread set me thinking once again that sometimes the model engineering fraternity are their own worst enemies. Surely the development of alternative silver soldering alloys is done within a much wider circle than our own hobby, with this in mind seeking the advice of those that produce them or use them is the better way forward. Making such sweeping statements such as this guy apparently did can lead to some pretty difficult situations in any one group. We all have members in our midst like this, very often the only factor about them that gets them audiences are their loud voices.
Sorry this is more of a rant than comment. Stan.

[havoc]

Flow is different witout doubt. But using correct procedure and fluxes this shouldn't be a problem. I have no other than Cd free solders in house and they flow pretty well. So good in fact I find them where they aren't needed.

The opening of this thread set me thinking once again that sometimes the model engineering fraternity are their own worst enemies

Exactly. Head in the sand and only looking back.

[Jo]

I know that there is a push to buy this cadnium free stuff but Johnson Matthey will still provide "real" silver solder . I notice that a number of the model engineering suppiers have also gone back to supplying the original due to the bad reputation of the Cad free stuff.

Silver Solder is even cheaper if you buy it directly from Johnson Matthey and there is no worry as to the type you get (I have noticed a few suppliers claiming that they could not say if theirs is cadnium or not), but you may want to club together as there is a large minimum order.

Jo

[Shawki Shlemon]

I was in the meeting and what Ian Kirby said is word to word of what took place . I only used one lot of the new stuff as I had a lot in store , it is harder using the same flux but if you give it reasonable clearance to flow, it will . As said above try on a specimen first. The future of the copper boiler is fine in my opinion , the reason is the cost will be higher but in the scheme of things it will be acceptable and the price of finished model will be marginally higher .Every thing else is more expensive .

[havoc]

I only used one lot of the new stuff as I had a lot in store , it is harder using the same flux

And was that the recommended flux?

[baggo]

ausdan said:

Hello Danny, and anyone else interested,
There was a short informative talk given by Dave Giles, a visitor from NZ. He outlined some POTENTIAL problems using cadmium-free silver solder on copper boilers, and particularly bronzes used for boiler fittings. It SEEMS to resist good penetration. The outcome from the discussion was that cadmium bearing solders are probably a lot EASIER for amateurs to use

Where in that statement is there any positive indication that cadmium free solders are not suitable for use in copper boilers

Wasn't it the AMBSC who would not accept Martin Evan's design for his boilers without crown stays despite there being hundreds built with no problems? Ostriches burying heads ?

[ausdan]

baggo said:

ausdan said:

Hello Danny, and anyone else interested,
There was a short informative talk given by Dave Giles, a visitor from NZ. He outlined some POTENTIAL problems using cadmium-free silver solder on copper boilers, and particularly bronzes used for boiler fittings. It SEEMS to resist good penetration. The outcome from the discussion was that cadmium bearing solders are probably a lot EASIER for amateurs to use

Where in that statement is there any positive indication that cadmium free solders are not suitable for use in copper boilers

Wasn't it the AMBSC who would not accept Martin Evan's design for his boilers without crown stays despite there being hundreds built with no problems? Ostriches burying heads ?

I think it was more of a case, of what some experienced boiler inspectors have found, give a heads up to fellow boiler inspectors, so they can go out in the field and watch for potential problems, give advice to the new comer, to watch for this as it seems it could flow different, or even gain experience to recommend a different set of guide lines for joint preparation, fluxes or technique..((which is what the 1st poster is asking))

hopefully, with our standard requiring checks at different stages of assembly, if any problems it can be rectified before the whole assembly is completed.

Since I'm a armature boiler builder, sounds like good advice, picked up 1kg of 45% silver solder with cadmium today, $495 AUD - ouch

[Shawki Shlemon]

Havoc
I used the same flux I used before on silver solder with cadmium , and that is flux comweld No2 recommended for comweld 245 (45% silver) .The code does mention high cadmium content , but it was harder to flow but as I said it will flow with clearance ,at least it did with me . If I have to buy more silver solder I will be looking for some with cadmium content .

[AndrewP]

OK, silver solder, at last a subject on which I have at least some experience.
When the cadmium free solders were introduced a few years ago there was quite a furore among silversmiths - it doesn't flow, it's too hot etc. etc. Whilst it is true that a lot of the first formulations were distinctly different from the old favourite cadmium bearing solders, especially on the first melting point (solidus point) being much higher we just got used to them and formulas have been improved.
A free flowing solder, which is a general characteristic of cadmium bearing formulas will flow through a joint more easily but is not as tolerant of variable gaps so complete filling is not as easy. It does form a neat, small fillet though.
Thicker solders, which can be a tendency for cadmium free formulas will not be as willing to flow through a joint so may need longer heating or modified technique (longer heating can affect flux choice) but will fill bigger gaps.

As an aside, at silver soldering school we were given a "mantra" of 'silver solder won't fill gaps' when preparing a joint and were taught to produce a light tight joint before attempting to solder.

A glance at a site like Johnson Mattheys www.jm-metaljoining.com/products-pages.asp?pageid=60§ionid=3 will tell you more than you ever wanted to know about the stuff.
I did notice that some of the cadmium free products contain tin which makes them hot short so should not be quenched.

The practical upshot of all this is that correct technique and flux choice will mean the cadmium free solders are fine for our use, and they might not kill us as quickly.

For me technique can be summarised as narrow gaps (JM suggest 2 to 6 thou, 0.05 to 0.15mm), place solder on one side of joint and pull it through with heat from the other side and a long lasting, high temperature, flux like Tenacity no5 work day after day.

We are all, of course, soldering with adequate, preferably forced, ventilation aren't we?

Cheers, Andy

[baggo]

agatehouse said:

We are all, of course, soldering with adequate, preferably forced, ventilation aren't we?

Haven't got much choice Andy - have to do my boiler making outside in the garden ;D

Incidentally, cadmium free solders have been around since the 1940's so are hardly anything new.

The heart of the matter is that people do not like change and are reluctant to accept anything 'new' or 'different', especially if they feel it is being 'forced' upon them. Anyone who had never used cad solders and started straight away with the cad free would never know the difference.

[AndrewP]

Spot on John, the 40s eh? strewth I'm not that old, it was only recently it became bad for us though and the jewellery community got in a tiz, all settled down quickly enough when we got used to it and you're dead right, the differences are subtle and not of any real consequence - the warning re tin content was new to me though and is worth bearing in mind, I habitually quench, probably from too hot, naughty boy.

[circlip]

Whoa, where did gap filling properties of silver solder come in? Solders whether silver, brass or soft are NOT gap fillers. They are when the basic machining or fitting is cr4p but there is no inherent strength in a badly fitted "filled" joint

[AndrewP]

circlip said:

Whoa, where did gap filling properties of silver solder come in? Solders whether silver, brass or soft are NOT gap fillers. They are when the basic machining or fitting is cr4p but there is no inherent strength in a badly fitted "filled" joint

I raised it because it is one of the properties referred to by the solder manufacturers.
Having practised my above mentioned 'mantra' for over 30 years I have often wondered about the advice given in ME texts to 'leave a gap' for the solder to flow it being against my training and experience. I have never questioned it because what I do every day, gold and silver at jewellery scales, is very different from say a boiler.
I hope it was clear I wasn't referring to 'caulking' a joint but to the deliberate fit of the components.