Solder problems

[Margaret TrelawnyParticipant @margarettrelawny34058]

Hello all

i am having problems soldering a brass tube to a small mild steel frame. I am using TSC A8 stainless steel flux and a small micro torch. I did a test on a small piece of tube soldered to a mild steel washer – but now when I try the same materials on the actual parts – it won’t have it. The solder seems to stick to the steel and also to the brass – but then instantly falls apart so a bond is not being made.

What am I doing wrong? Both parts are cleaned with emery then 99% isopropyl.

Is there a better flux or a particular solder you could recommend?

thanks in advance

Margaret

[Margaret TrelawnyParticipant @margarettrelawny34058]

Brass to mild steel

[JasonBModerator @jasonb]

You don't say what solder you are using

[Anonymous]

Whatever the solder the choice of flux seems unusual. The A8 flux is intended for soft soldering stainless steel and hence is quite aggressive, ie, contains acid. For brass to low carbon steel I'd use a low temperature silver solder and EasyFlo flux. Depending upon part size a micro torch won't provide enough heat.

Andrew

[Clive Brown 1Participant @clivebrown1]

As per Jason's question, but if it's a lead free soft solde type, then I'd change to tin / lead "electrical type" solder. It wets better. The flux is an aggressive type. I'd use an ordinary, resin type but probably not essential.

Edited By Clive Brown 1 on 30/06/2023 14:39:46

[Margaret TrelawnyParticipant @margarettrelawny34058]

Solved it. I changed the flux to LA’s brass/steel etc flux and it worked.

sorry for the panic!

[Margaret TrelawnyParticipant @margarettrelawny34058]

Agree Andrew. The flux was the issue. Someone suggested I try that as it worked for them

– i thought it strange but tried it.

Thanks Jason – the flux change helped the solder flow as it should.

I appreciate your time answering guys.

all the best

Margaret

[Margaret TrelawnyParticipant @margarettrelawny34058]

Jason – it’s a ‘general’ solder which came in a pack. It doesn’t actually give it’s content.

[Dave HalfordParticipant @davehalford22513]

'Tin' the steel first before putting the two parts together. I suspect the micro torch does not have enough power, the kitchen hob would be a better supplier of heat.

[Richard MillingtonParticipant @richardmillington63972]

I use LA plumbers flux (as I have some from plumbing jobs) works for me.

[Margaret TrelawnyParticipant @margarettrelawny34058]

Richard – yes LA Plumber’s flux did the trick and it’s for a vintage puppet solenoid restoration.

Dave – the micro torch did the job perfectly. 😊

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