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[OT] Rant about soldering

Posted: Tue May 22, 2007 2:20 am
by sebovzeoueb
Why is it that the back of volume pots on electric instruments seem to be made out of a metal designed especially for solder not to adhere to them!!?? AAAAAARRRGGHH!!! Surely something can be done about this other than my usual "mountain of solder until it stays" approach...

Posted: Tue May 22, 2007 2:51 am
by rbmonosylabik
Some sandpaper can help

Having said that...

I just soldered a cable. FUCK SOLDERING!!!!

Posted: Tue May 22, 2007 3:01 am
by bragi0
Rough the surface up with a brillo pad or sandpaper. It's usually a coating on them that's preventing instant take. Also, use flux after rubbing them.

Soldering isn't hard :S

[looks at burns on fingers]

No worse than working in a kitchen anyway.

Posted: Tue May 22, 2007 3:08 am
by Tone Deft
The problem is the sheer mass of metal you're working with, the pot shold melt the solder and it's going to take longer to get all that metal heated up, patience!

Do not take the 'mountain of solder approach' you'll get a weak, cold solder joint.

The key to soldering is to heat both pieces of metal, they in turn heat and melt the solder. If you're dropping hot solder onto cold metal you will not get a solid joint.

Take your time.
Put the wire onto the pot, wrap it around, put it through the hole if there is one.
Hold the soldering iron into the joint, wait 5 seconds.
Put the solder 'wire' NEXT TO the soldering iron.
Hold the solder and the iron down until the POT METAL melts the solder.
Let the solder wick up into the wire like melted wax going through a candle wick.

I've done thousands of solders, I feel you. Do this wrong and you're only asking for more work later.

Solder flux can be used to make the solder flow better. Make sure you're not using RoHS or lead free solder check wikipedia on RoHS but it was an EU ruling that went into effect a year ago taking lead out of electronics including the solder. The lead free solder is like cold peanut butter and it melts at a higher temperature then the old solder. The solder reel will say 'lead free or RoHS compliant, or it will list the contents, lead (pB) should be in there.

Posted: Tue May 22, 2007 5:07 am
by sebovzeoueb
I'm talking about soldering onto the back of the pots (so onto a smooth surface rather than a tab with a hole) but thanks for the tips, this may help me in the future.

Posted: Tue May 22, 2007 12:40 pm
by Synthbuilder
The other poster was right. You need to rough up the pot casing a bit. I use one of those little polishing blocks. Made from hard rubber and a lot of grit embedded in it. And if that fails, scrape the surface until very shiny with a flat bladed metal screw driver.

And, don't be using that new fangled lead free solder either especially if you have an older soldering iron. The old Rosin cored stuff eats through oxides faster, and the lead/tin mix melts at a lower temperature.