Soldering onto pots. . .

[thearabianmage]

I've just spent a very long time trying to solder wires back onto a pot - the bundle that was soldered on just popped out of place, hovering slightly above the pot, and wouldn't go back down.

I had to take all the wires apart put a glob of fresh solder onto the pot, then glob on more solder with each wire. This was the result of nearly an hour's trial-and-error. Nothing else worked: sanding (50, 80, 600, 800 = nada), wiping with a moist cloth, reheating the solder from all angles, letting it sit for a second. Bad times.

Can anyone explain why this is and how to get by it? I thought the pots might be dirty, but they're new (yes - two offending pots in question. . . the buggers)

They are CTS audio tapers if that makes any difference to anything.

Cheers y'all

It's 6AM. . . .bedtime. . .

[WackyT]

Did you use flux?

http://www.seattlerobotics.org/guide/images/flux.jpg

[F_BSurfer]

You might check the tip of you iron take some of your sand paper clean it good

[Tibernius]

I've just spent a very long time trying to solder wires back onto a pot - the bundle that was soldered on just popped out of place, hovering slightly above the pot, and wouldn't go back down.

I had to take all the wires apart put a glob of fresh solder onto the pot, then glob on more solder with each wire. This was the result of nearly an hour's trial-and-error. Nothing else worked: sanding (50, 80, 600, 800 = nada), wiping with a moist cloth, reheating the solder from all angles, letting it sit for a second. Bad times.

Can anyone explain why this is and how to get by it? I thought the pots might be dirty, but they're new (yes - two offending pots in question. . . the buggers)


How many watts is the soldering Iron?

According to one of the books I've got on building guitars, some pots are plated and you need to file the plating off or the solder won't stick to it. Could be that the sandpaper wouldn't remove the plating? :confused:

[ShootTheGlass]

If youve cleaned up and roughed the surface, and youre using flux cored solder, id guess that the problem lies in your soldering iron not being powerful enough.

I use a Bernzomatic gas powered one I got from B&Q, adjustable, but on full pelt is more than enough to solder onto pot casings.

[thearabianmage]

Hey, thanks everyone for the help! A couple bits of info:

1 - I'm not sure what flux is, but I thought flux was in the core of the solder? If this is a different flux, what does it do?

2 - My soldering iron is between 20 and 25 watts. But I haven't changed the tip in quite a while. . . (was a pencil tip. . . now is a bit more of a stump. . .)

Could that be it?

I had no problems soldering onto other components. . . Just the pots.

Cheers y'all!

[marnold]

Hey, thanks everyone for the help! A couple bits of info:

1 - I'm not sure what flux is, but I thought flux was in the core of the solder? If this is a different flux, what does it do?
Yeah, it is a part of the solder you're using, but this is a separate thing like the picture WackyT posted. I ran into the same problem when trying to solder a ground wire to the claw of my Floyd. My iron is 20/40W switchable so I ended up using the 40W setting and heating the living daylights out of the claw. Obviously that method won't work with electronics--even pots that are more heat-resistant.

From the sounds of it you might want to replace the tip on your iron too.

[Spudman]

Flux is a paste usually in a tube that you apply to the area to be soldered before you start to heat the area. It makes the solder stick and flow easier. It is separate from the roll of solder.

[thearabianmage]

Most excellent, thank you everybody! :AOK:

[duhvoodooman]

Between sanding the back of the pot and using a resin flux-core solder, adherence really shouldn't be a problem. So it sounds like you're not getting enough heat into the back of the pot with your iron and need a better tip or more wattage. 20 - 25W is right on the ragged edge, but I use a 25W iron for this kind of thing all the time, w/o problems. So clean up or (better yet) replace your tip first, and see if that does it.

[murph]

You might have a solid solder, in which case you have to apply flux separately. It is easier if you have resin core solder, and a clean tip.Your solder iron sounds like you need a tip replacement.

Murph

[Duff]

I'm a good solderer and I use flux, especially when I'm not getting a good quick adherence of the solder to a surface or wire.

I usually scrape or sand off any slag from my soldering iron tip. This slag looks blackish and may be flaky or caked on to the tip. I get it off by scraping with the back side of my exacto blade or with sandpaper.

Then I apply some flux, as from the tub illustrated above, to the tip and then apply some rosin core solder to the fluxed tip to cover the tip with a coating of solder. This is called "tinning the tip". Tinning the tip will create a contact surface when you solder your wires onto the pot. You will be soldering solder with an object, the tip, that also has solder on it.

I always flux and solder my wires first before connecting them to the ground on top of the pot. I always avoid using large puddles of solder. The least amount of solder you use the better it is but it needs to be a sufficient amount, not a pile; like you often see.

After I clean and tin my iron tip, flux and put a thin amount of solder on my wires, I apply a small amount of flux to the surface of the pot, usually never sanding the pot surface. A small paint brush type applicator for the flux comes with the tub and you get the flux at Lowes or Radio shack. Ask for solder for electronic projects and you will get solder that "contains" lead. This is excellent to use with electronics but not on potable water joints. This solder melts quicker. Get a thin diameter solder at Radio Shack for instance. Not this big thick diameter stuff and definitely not this lead free modern solder made to melt at way higher temps.

After fluxing the top of the pot I put the wire on there already coated with a thin amount of solder and apply the iron to the top of the wire, pushing down slightly against the top of the pot. After a few seconds with a twenty five watt iron the area is sufficiently hot to apply the solder. Do not apply the solder to the tip of the iron but rather to the wire near the tip and the heat will "draw" the solder into the heated area, penetrating the wire almost like water and flowing down to the surface of the pot where it spreads and bonds firmly, with the aid of the flux.

Apply other wires as needed. When you get better you can twist ground wires together and do a few at one time. This requires less solder. Supposedly a pile of solder will soak up the tone.

Don't overheat the pot because this will damage the electronics inside.

The purpose of flux is to heat up with the tip and burn off impurities and oil, coatings, etc., from the surface of the things you are trying to solder, making for a properly prepared soldering surface prior to the actual soldering.

Fluxing a surface is kind of like applying primer paint before the final coat. The primer sticks to the surface much more firmly than the final coat type of paint would if used by itself without primer first. And, the final coat adheres more firmly to the primer paint than it would to an un primed surface. So you get double increase in the strength of the paint adherence.

Flux helps solder adhere better and makes soldering possible when, as in your case, the un fluxed solder just wants to bead up and roll off. The solder will sheet out and penetrate and way less heat is required.

Be sure to go to Radio Shack, no affiliation, because they are about the only place you can get solder that contains lead. This solder is for electronics, ask for solder to use on guitar connections. It melts at a very low comparative temperature. They have several thing diameters. The type I'm using on guitars right now is about a little less than a sixteenth of an inch in diameter, about one millimeter in diameter. It is rosin core.

If you use these practices you will have success, most definitely; most likely.

There are others that will give you other instructions, like not to use flux, however, you are having difficulty and the use of flux will greatly, greatly facilitate your development of soldering skill. It's easy and fun!

Watch out when soldering that you don't melt the colored plastic insulation off of surrounding wires accidentally. Easy to do. The shaft of the iron gets hot enough to do it. A "pencil" type soldering iron rather than a gun type is easier to get into specific difficult to access areas with other insulated wires everywhere. The pencil type is slim and gets to the point without extraneous apparatus taking up limitted space. Guns are neat but not for this type of thing. Unless maybe you are a very good solderer.

A solder joint, by the way, is very similar to a weld joint and should be very strong, even when using a minimal amount of solder. Large piles of solder are rarely found when a professional soldering job is done by a good guitar tech.

Hope this helps. From a totally amateur solderer but one with a lot of experience. I do some big piles too by the way, but try to avoid it.

Any time I get the problem of the solder not sticking I brush on some flux and the solder sticks like a good weld.

Glad to help,

Duffy
mjbolduc@dejazzd.com

[tremoloman]

I'm glad this question was asked... I've always struggled with getting wires on the backside of brand new pots. I need to replace the volume in one of mine this week so this came up at a great time!

:master:

[mrmudcat]

Nice post Duff!!!!:master:

Very thorough and accurate:beer:

[WackyT]

Very good explanation Duff. Just have to add one more detail though. Flux is a corrosive, so clean off as much of the soldered area as possible after done soldering with denatured alcohol.

http://images.rockler.com/rockler/images/55624-01-200.jpg

Do not use supermarket isopropyl or rubbing alcohol.

http://www.chemistryland.com/CHM107Lab/Lab1/RubbingAlcohol.jpg