Silver solder flux

Hello all.

I am about to start the process of trying to solder the boiler on my 1" Minnie.

I will purchase the solder possibly from Cup alloys, seems as good as anywhere,

I have been given a small tub of Johnson Matthey flux, is this ok to use with Cup alloy solder ?

I would have thought it would be ok, but want to check.

Thanks.

Seems obvious to me to ask the guys at Cupalloys about the compatibilty?

I have used Johnson Matthey flux with Cupalloys solder without any problems. It might be wise, mainly for your peace of mind, to use the combination to join a couple of bits of scrap copper as a trial. Also, perhaps have a word with the person who might inspect your boiler.

JA

Which JM Matthey flux is it? If it's Easyflo flux, I wouldn't use it on a boiler. It doesn't last long enough at temperatures for the length of time you need it to work for boilermaking. I've used Tenacity 5 with much better results.

If flux gets oxidised in a joint before the solder has run in, you've very little chance of recovering it as you can't get in to clean it for re-doing it later.

Easyflo is fine if you're doing non-ferrous fittings (I never use it on steel) when the heating time is quick.

The only disadvantage of Tenacity flux is that it's harder to get off after it's glazed, but the integrity of the joint is far more important than the expenditure of a bit of elbow grease.

Thanks all.

John, your right, spoke to Cups and they have confirmed easy flow is ok to use.

JA. Would have liked to get the boiler officially inspected but never got round to joining a club, i think if i turned up at this stage with me box of bits they would tell me where to go, have made a small tester for my own piece of mind.

Nigel, good advice, shame there are no night school classes running courses on this sort of thing ( do they still do night school classes )

Thanks all, can feel a massive learning curve approaching..again..

We wouldn't tell you where to go, but then we're a friendly lot 'oop north', where are you located? If you intend to run your engine in public you'll need insurance, and joining a club is the easiest way to get the boiler certified.

Based in the midlands so possibly the black country live steamers would be the best for me.

**LINK**

Will have to drop them a line, see what they say.

I believe getting the boiler inspected and "certificated" is part of the process of making a boiler (or such like).

Many (most?) people initially join clubs, not just model engineering clubs, for what they can get from the club. In other words they join for selfish reasons. I joined my local model engineering club for precisely this reason, I intended to make a boiler for a Stuart 7 engine and want it "certificated". I have yet to start making the boiler.

JA

hi Brian,

you are about to embark on quite a costly part of the build, and i would encourage anyone to have a go at their own boiler to a published design, so good luck.

however it is easy to make a real hash of things if done in the wrong order, wrong fits, wrong methods, wrong set ups and heat etc. add to this list use of correct grade of silver solder and flux for boiler making.

i would strongly endorse Nigel Bennett's excellent advice. J-M Easyflow flux is ok for small non ferrous components ideally with the old cadmium bearing easyflo and easyflo2 silver solders. for J-M silverflo55 silver solder you are really pushing the flux. it is totally unsuitable as a flux for long heat ups required for boiler work.

Nigel has suggested J-M Tenacity 5 which is designed for stainless but quite ok. i use Tenacity 4A or its equivalent Thessco F flux for boiler work. Alec Farmer recommended i use Thessco F 30 years ago for my first boiler, as this is what Alec used himself.

any flux deposits with these are removed by a soak in a hot solution of sodium hydroxide, as recommended by J-M themselves.

if you use easyflo flux for making your boiler that will be your first mistake!

second mistake is not joining a local ME club. you will also need to get all stages of the boiler construction checked by the club boiler inspector as you go along, and he may also require departures/updating of the original design to comply with the current boiler regs.

cheers,

julian

Edited By julian atkins on 11/11/2015 16:44:21

Thanks again for the advice, trying to find a local me club to help me on my way,

Cheers

good luck with that one

Be fine, I'm sure

Hi Brian,

Suggest you look at www.cupalloys.co.uk/best-practice/

http://www.cupalloys.co.uk/best-practice/

Load your printer and you will end up with a comprehensive book that will answer most of your questions and offer guidance on achieving strong leak-free joints first time.

Regards

Keith

Edited By CuP Alloys 1 on 13/11/2015 13:57:23