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What do i need to do this

Bulldog Steve on Mon October 26, 2009 10:05 AM User is offlineView users profile


How do i solder steel to copper. The steel is slipping into the copper

Thank you.


bohica2xo on Mon October 26, 2009 10:50 AM User is offline

How much joint clearance do you have? Will you be able to clean the assembly after soldering?

For soft soldering:

A decent flux will solder to clean mild steel. Any flux that will give good results is acidic, and will need to be removed after soldering. Avoid acid core solder, and use a paste or liquid flux.

If you have plenty of clearance, you can tin the steel before assembly, then clean the flux off before sweating the parts together.

For brazing:

Use a good commercial flux, and get a thin film of it in the joint before heating. Use a silver bearing filler with cadmium & zinc, it will wet both metals nicely & melts @ 1150F.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Bulldog Steve on Tue October 27, 2009 7:52 AM User is offlineView users profile

Thanks for the info and help.


NickD on Tue October 27, 2009 10:36 AM User is offline

Steel has to be tinned first, I have a bottle of La-Co steel flux that does the job, but it's strictly outside work, that stuff will kill you. Both the steel and copper have to be sanded well for a very bright finish, can use either acid or rosin core flux on the copper, prefer acid, but both the copper and steel have to be cleaned off first, denatured alcohol works well, can joint the piece together and finish off with rosin core solder to get a nice looking bead around the joint, best to have the larger diameter pipe facing toward the sky so the solder works in the joint.

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