Can't get hot enough to solder

[paul]

I managed my first silver solder (at first attempt!) today while re-constructing my boiler. For reasons I won't go into, the first solder was the central flue to the bottom flanged plate and, I think because there was a realtively small amount of copper involved it worked fine.

However, now I've come to solder that assembly to the boiler body it just won't have it, I assume because the heat is being conducted away by all that copper. Although the solder has attached itself to the parts it just went dull grey and didn't flow at all.

I've got the work set up on some patio blocks because I haven't got any other suitable surface. I even tried covering some of the block with foil to reflect the heat back but to no avail. Short of going out and buying some kiln bricks does anyone have any suggestions for a quick fix to up the temperature? I'm using a DIY 'Go Gas' type blow lamp BTW.

Thanks as usual

[havoc]

First, when you say solder, wha do you mean exactly: solder with tin/lead (plumber), solder with tin/lead/2% silver or hard solder with 10-40% silver?

Do you give it enough time? This was my biggest problem when starting to braze. Trying to rush the job.

If heat output is a problem, then try to enclose as much as possible of the job at hand. Ytong has been proposed, regular fire bricks etc. Put the brick as close to the work without touching leaving only the part you work on exposed.

[ron]

Paul
I'm new to this boiler making lark as well although I've a fair bit of experience of brazing and silver soldering, basically I don't think you have a big enough blowlamp, you aren't getting enough heat, these DIY ones are only suitable for small jobs even with a sort of kiln built round them. The propane burner my pal has that we are using for Simplex boiler is a ferocious piece of equipment, OK you don't need something that big, you could try using two torches to see if you can raise enough heat that way. I've also been using a pressure petrol stove for annealing copper and it will heat a surpisingly large piece of 1/8" copper to dull red and can also be assisted by a DIY propane torch.
If you can get old storage heater bricks they are a cheap source of kiln material.
Ron

[baggo]

Hi Paul,

As Ron says, the DIY type blowtorches just won't give out the sort of heat required for serious silver soldering, you're going to need a proper propane torch with separate gas bottle and regulator. Although Sievert are probably the best they are relatively expensive. Machine Mart do some quite cheap sets that are pretty good. The propane bottles can be got from caravan dealers etc.

Enclosing the job can help a lot but you have to be careful you don't restrict the air supply to the burner or it will keep going out. Most infuriating! Lightweight Thermalite building blocks are excellent for making a brazing hearth and enclosing the work as they don't absorb any of the precious heat and are good insulators. Don't use the ordinary heavy concrete ones as they may explode with the heat.

John

PS Quick improvised brazing hearth! :

[paul]

Arrghh, more expense... I feel a domestic coming on!

Havoc, it's silver solder. I'm not rushing it... I must have used half a can of gas on that one attempt! Ron, John: I'll see if I can enclose the job a little more before I rush out and spend more of the kid's Christmas presents

The plate I'm trying to solder is recessed about 1/2" into the boiler (about 2.5" dia) so it's not a big job but it's so frustrating when the flame keeps going out - good job I had a box of 'cooks matches' .... i'd have been through two boxes of Swan Vestas by now!!

[steammadman]

Paul, freind Baggo is quite correct, YOU ARE NOT GETTING ENOUGH HEAT.
those "go gas" type blow lamps are as much use as a chocolate fireguard
for boiler making.
If you want to avoid a "domestic",and after nearly 50 years of them, i'm an
expert, i suggest you go along to a local small tool hire compay and hire a
sievert blow lamp and gas,get a medium /large nozzle ,pack your job like
Baggo shows, fire up, and you'll be surprised at the difference, and you
should get a result.
GOOD LUCK

[Shawki Shlemon]

Hi
Golden rules for silver soldering
1 - 100% clean
2 - somewhere for solder to go ie ( clearance ) .
3 - heat until flux run clear.
4 - patience and do a small area then repeat 1 , 2 , 3 .
Good luck

[John Lee]

shawki said:

Hi
Golden rules for silver soldering
1 - 100% clean
2 - somewhere for solder to go ie ( clearance ) .
3 - heat until flux run clear.
4 - patience and do a small area then repeat 1 , 2 , 3 .
Good luck

Ahh the voice of experience.. too which I might add... too much heat is better than too little. Get it all very very hot.. Copper melts a fair bit higher than silver solder

John

[havoc]

And the advantage of using propane is that you cannot melt the copper!

I read in a LBSC book that "you have to be able to see through the copper when it is ready to solder". I found that a very good way of putting it.

[chris vine]

Hi Paul,

Silver soldering. Although someone above says don't hurry it, you must get the job hot enough and fairly quickly. The flux is an active substance and it only keeps the oxides away for a few minutes, then it is exhausted. It may be this exhaustion that is making the solder look grey and not run.

If you need a propane cylinder (propane much better than butane) then it will be a red one, and it is supprising how often they are down at the corporation tip. Some even have gas in them!

Equally the gas stockist, if of the larger type, may well just let you have cylinder, buck-shee, as long as you take it back to them to fill up.

As an interim solution, you could try surrounding the work with bar b que charcoal. There will be a few sparks flying but the heat addition/reflection from the charcoal will be very powerful....

Chris.

[paul]

I managed to solder some small parts with no problem - I think its the size rather than lack of technique/preparation.

What does anyone think of this...

www.machinemart.co.uk/product.asp?p=010110101&r=2037&g=105

...it's a bit more palatable than the £80+ Sievert types

[ron]

Paul
I thought this looked not a bad kit for the money, I'm thinking of investing in one rather than keeping borrowing and at the rate these disposable canisters empty it would probably pay for itself as well.
www.machinemart.co.uk/product.asp?p=010110560
Ron

[baggo]

Paul,

The kit you're looking at is only really meant for soft soldering I think. The kit Ron mentions is good value for money. My brother bought one and managed his Rob Roy boiler using it (with a bit of help!). There's every size burner you are likely to need. If you don't want to splash out that much money, have a look at:

www.machinemart.co.uk/product.asp?p=010110108&r=2037&g=105

The burners are suitable for boiler work although the smallest is a bit big for small fittings etc. Your existing setup is probably ok for the small stuff anyway.

John

[paul]

Thanks for the guidance chaps. John that second one looks more reasonable... is that everything I'd need except the gas?

[baggo]

Yes, it includes the hose and regulator. It's a pity you can't buy the nozzles seperately so you could add some smaller ones later. I did wonder if the Sievert ones would fit but unfortunately they are a different thread!

John

[Steve M. W]

As a thought you could always go to a night school and use the gas and air equipment plus you can get some of your other question solved. I go to one in Aldridge which is very friendly
and everyone helps everyone. you work on our your own project not a set piece by the School.

Steve

[paul]

What's the class Steve?

[Steve M. W]

Hi Paul
It’s a model engineering class but we meet more like a club very informal Thursday nights 7.00pm -9.00pm its at Aldridge School Tynings Lane, Aldridge. Come down and have a look we only have two or three night left this term but you are more than welcome.

Steve

[davidimurray]

Hi

Just spotted the thread - you want one of these

www.machinemart.co.uk/product.asp?p=010112941&r=2037&g=105

It is the same as the sievert torch - probably made in the same factory! I built 2 Conway boilers using that torch alone - the only thing I had to do was buy a big Sievert nozzle to do the foundation ring.

As it is the sievert torch under a different name all the sievert fittings/nozzles will fit it as well.

Cheers

Dave

[steammadman]

Thats the one,seivert nozzles do fit, and ,with dferent size burners you will get ALL the heat you nead,but, dont forget fire bricks around the job to keep a bit of the heat in.
Also remember a good quality flux mixed with a good quality silver solder is usually half
the battle.
Also have a little p ractice on some scrap brass ,steel,copper etc before you start on expensive boilers etc, remember , a small cock up on the boiler makes you the scrappies
friend,and the me suppliers banker.
have a go and good luck.