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Anyone here know how to solder?

Discussion in 'Technology' started by halo five, Oct 15, 2005.

  1. halo five

    halo five TRIBE Member

    Everyone says soldering is easy, but I'm having trouble picking it up. I've been practicing on scrap with limited success -- I'm trying to wire a bass guitar I'm building. Fairly simple wiring job to start out with, I thought.

    I'm using an inexpensive 30w "pencil" soldering iron, with fairly thin solder. I've read online tutorials but I consistently have the following problems:

    1) I can't "tin" my soldering iron more than few times before it won't take any more solder. I've been through 3 tips today already. Is this normal? After a 3 or 4 connections, the tip is black and oxidized and solder just beads off it.

    2) I have 2 pots I'm going to be using on this project. They're fairly big 250k pots. However, they won't take solder at all! Do I need a more powerful soldering iron to heat these pots up? Will the excessive heat damage the pot?

    Any tips are appreciated. I'm pretty frustrated!

    I bought a small box of flux, supposedly to make surfaces take solder more easily, but it's a solid cube of amber stuff, and I don't know what to do with it. :confused:
  2. zoo

    zoo TRIBE Member

    i've never (ever) replaced the tip on my soldering iron .. and this is a hand-me-down from my dad from the 70s
  3. Rataxès

    Rataxès TRIBE Member

    Most solder is flux cored, so you don't need any additional flux (although some paste flux is good to clean the soldering tip).

    Re. tinning the tip, I usually flux the tip before and after use by meling a bit of solder onto the tip and then cleaning it off with a wet paper towel. This fluxes the tip - cleaning it and allowing solder to flow off of the tip; solder should bead off it when it is hot - the oxide is probably flux build up - clean the tip off.

    Are you giving the soldering iron enough time to heat up? A little 30w iron may take 4-5 mins to get up to temp. When soldering, with a small iron on large guage wire, it may take a little while for the item being soldered to heat up. Apply solder to the component being soldered, not to the soldering tip, otherwise you may get a cold solder joint. Always clean you soldering tips before and after use (apply a bit of fluxed solder to the tip and shake it off).
    Last edited: Oct 15, 2005
  4. alexd

    alexd Administrator Staff Member

    the unknown solder
  5. halo five

    halo five TRIBE Member

    I let it heat up 10 minutes or so to make sure - And yes, I read that you apply to solder to the components being joined, not the iron, but I have to cheat a bit - I apply the solder to the components and the iron at the same time, and let it flow around the components, removing the solder then the iron. Is this wrong? I've never been able to get a component hot enough to melt the solder without touching the solder to the iron, at least a little bit.
  6. blueshrike

    blueshrike TRIBE Member

    you need a better soldering iron i think.

    I had a crappy one for years and it was always a hassle to get the solder to take. Especially if the contacts were dirty or the wires to thick. I also had to cheat. Which really does lead to an inferior joint.

    Eventually I figured out that it wasn't my mediocre soldering that was the problem when my dad (in a fit of cursing) used his blow torch to heat the tip up till it was glowing. We had no problem soldering with it that day.

    Mind you it never worked properly after that.
  7. oddmyth

    oddmyth TRIBE Member

    a 30w iron should be enough, however that said cheap irons don't maintain constant temperature very well.

    You should have on hand a small damp sponge, as Rataxès pointed out, the blackness is due to burnt flux staying on the iron. I usually clean the tip of my iron about once every 10-15 solders (on IC's) and if I'm soldering large components probably quicker. A smooth iron tip will not only help with heat transferrance, but also allow the solder to slide down the tip more easily. I've never changed a tip ever. It could be that your iron isn't holding temperature well at all.

    For the pots, yes you can damage them, but I've soldered a fair number of them and they are harder to damage than some other electrical components. What you need to do is heat the connector, while holding solder to it, and pressing in on it. Once the solder starts to melt even a bit, pull the solder off, and heat the actual joint (the wire will heat much more quickly than the pot) and apply the solder. It can be tricky, in my old shop I would usually find a similar old component and do a time test on it, then apply the results to the new component I was about to use, especially in audio and timing applications where a good solder joint can cause indeterminate results.
  8. labRat

    labRat TRIBE Member

    key is to apply the flux, then heat both the pads and connectors. after a few seconds you should be able to apply the solder. if that don't work then you need a new iron.
  9. halo five

    halo five TRIBE Member

    "Apply the flux" - do you mean apply the solder (the solder having a rosin core)? The flux I have is a big amber cube. I'm reading that there's liquid and powder flux, but this is a solid block, I don't know how to use it. It was the only flux they had in that electronics store on Queen near John.

    Oh, to clarify, I've managed to solder to the terminals on the pot (there are 3 of them), but what I'm having real trouble doing is soldering a ground to the actual casing of the pot.

    Thanks for all your help thus far!
  10. labRat

    labRat TRIBE Member

    never used a solid flux - usually liquid and goopy/sticky.

    grounds are very difficult to solder actually, easiest is to get two soldering irons working together but you only have one. so just apply the heat for a long time - get as much surface area as possible of the tip onto the surface and try to poke the solder wire onto the surface (not the iron tip).
  11. oddmyth

    oddmyth TRIBE Member

    Ok the easiest way to do this is thus:

    1. heat the wire you are attaching and apply as much solder as you can to it.

    2. heat the casing of the pot in the spot you want to attach, then quickly place the wire there and continue to heat the joint. The excess solder will move onto the base and depending on the amount of solder you actually applied to the wire the joint will be either weak or of medium strength, use a little more heat and some more solder to solidify the joint further.
  12. halo five

    halo five TRIBE Member

    I'll try that, thanks. Someone else recommended a flat tip also, which makes sense - more surface area being heated.

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