Solder Cracking

[karrotbear]

Hello All,

Lately I have been noticing that my soft soldered joints are cracking, now I know this is because of the steep heat gradient, especially at points where the vapour path meets the condenser. Anyone else having issues with joints cracking? If so, any tips on not having it crack? Kinda getting sick of having to resolder the jonits :s

[Brendan]

Mate, if your solder joins are cracking at 80deg C, it means they were barely hanging on to begin with and they are letting go as the copper expands.

Sorry to say, but this is due to your soldering. My guess would be that you either don't have your surfaces cleaned and fluxed well? Or you aren't getting the heat right into both surfaces so that it forms a bond :think: If you are clean with your work, it's more than likely the former.

Depending on the type of join you are doing, you need to make sure you aren't just getting it hot enough so that it slightly melt and sticks to that area...it needs to 'flow' around the entire join you are working with...

You also need to make sure that you aren't applying heat directly to where you are soldering, as you will burn the flux and the join will be very weak...you need to heat close but away from the area and let the heat travel there and across the join to the other side of whatever you're joining, then the solder will flow and take to all the surfaces filling the gap.

Your solder should not let go from any expanding from heat that's for sure...it shouldn't let go until it heats to 400+deg C and melts... :naughty:

[karrotbear]

Awesome thanks for the advice. I think another contributing factor could be that, if I remember correctly, I didn't have/couldn't be arsed to go get some new soft solder, so I may collected all my splatters/drips/strings and remelted them into a soldering bar and then continued to solder :oops:

It is also not a traditional join. It is between a 32mm copper cap, and the pipe feeding through the cap. I had a 16mm (apparently) hole saw and drilled my hole, and the pipe was slightly too small, so I just put as much solder on as possible (trying to fill the hole).

:D:D

[emptyglass]

I'm gunna ask, but I'm sure you wouldn't be using plumbers/lead solder?

[karrotbear]

I only use the 100% lead solder (very hard to find now adays, believe it or not) :P

I use the Benzomatic silver bearing solder (blue label - Bunnings). Partly the reason why I decided to reuse the 'offcuts' :/

[emptyglass]

Nah mate, leave the stuff on the bench for the bin.
Penny wise pound poor, or so they say.
Don't skimp on solder, that one always bites back.

[MacStill]

Nah mate, leave the stuff on the bench for the bin.
Penny wise pound poor, or so they say.
Don't skimp on solder, that one always bites back.

Yep been down that road before, the remelted stuff never seemed quite as good.... tried and failed 8-}