Trouble wiring pickguards

[The Norwegian Guy]

I recently switched from a 500k vol pot to a 250k on my HSS strat.
I'm having trouble getting 4 different wires soldered to the ground on the pot.

I have sanded the chrome off the pot.
I think I might use too much / too little heat on my soldering iron. How many degrees celcius is necessary?
How the smack do you guys make 4 different wires stick to the same "solder-spot" without any of them "popping" off while the tin is hot?

Does anyone have any advice on this?
I'm almost giving this up, because I can't make it right! Concidering handing it over to the local guitar store to have them do it for me, but I really want to do it myself...

 

[bagman67]

Cagey is fond of suggesting soldering lugs as a solution.  You could also solder two or more different blobs of solder to the pot housing.  The pot housing itself will serve as a conductor for the various ground points.

 

[line6man]

You don't solder all that to the back of the pots, you run all your wires to the third terminal of a volume pot, then only one lead to the casing, or to some other ground point.

 

[The Norwegian Guy]

I see! Dammit, those wiring schemes fooled me!
Guess I'll have to open her up again today!

 

[The Norwegian Guy]

what is the ideal temperature, btw?

 

[line6man]

what is the ideal temperature, btw?

What solder are you using?

 

[The Norwegian Guy]

That, I'm not sure of. Some stuff my dad brought from work a couple of years ago. It's pretty decent. They used it in remote controlls and recievers for industrial cranes. That's all I know

 

[pabloman]

Twist the wires together and tin them. Also, sanding the pots can actually be causing a problem. If it is too coarse it will create somewhat of a heatsink and dissipate the heat. Good luck.

 

[Cagey]

what is the ideal temperature, btw?

There are several considerations regarding soldering temperature. Most electrical solder melts around 200°C/400°F, but that's just the start of your worries. You need to know how long it's going to take your part to heat up to that point, how long it can stay that hot, and what the recovery time of your iron is.

Parts with a lot of mass take longer to heat up. Also, parts with large surface areas, or thin metal surfaces. Sounds contradictory, but it's not. Mass absorbs heat, while larger/thinner surfaces tend to dissipate it. Either way, you're sitting on the part for a while to get it good and hot.

How long it'll stay hot depends on the same things, but it's not so contradictory. More mass means it'll hold heat longer, while large/thin materials dissipate the heat quickly. That is, they behave as heat sinks.

The soldering iron's recovery time has to do with how many watts it's burning, and the size of the tip. Pointed, conical tips tend to lose heat quickly, so the iron takes a while to reheat back to its starting point (before you touched the part you're going to solder).

All these things conspire to make soldering to the backs of pots problematic unless you're aware of them and compensate. Pot housings are large areas of thin metal, so they act like heat sinks. They don't want to heat up, and they cool your iron's tip down. Between those two things, you end up sitting on the pot for a long time waiting for everything to get hot enough. All the while, the part's slowly heating up as well, so you have a better chance of wrecking it.

Best thing is to not try it. You're quite likely to burn the pot up internally, or at least deform/deteriorate the thing so its life expectancy is shortened. That's why I advocate using lugs.

But, all is not lost. You can get a larger iron with a chisel tip, and usually get away with it. In my experience, the iron should be about 40-50 watts with a chisel tip. No smaller, no pointed tips. Ideally, you probably want something even larger, so you can get on/off the part quickly, but you need a larger iron so rarely most people don't make the investment. A 40 watt iron can be used for damn near anything electronic, so it's a good compromise.