- Thu Jul 07, 2011 9:57 am
posted by: swhenrik
Posted - 01/22/2008 : 08:42:51
The links above will give you some good ideas of the basics of soldering. But keep in mind they are talking about soldering small components. For anything we do here, we are usually dealing with larger wires and connectors. Getting a good solid solder joint to handle high current is more important then being "neat". So, I'll throw a few of my own tips in here also.
What is "Tinning"?... It's touched on in the links above, but if you don't wanna watch the video.... it just means to add a bit of solder to the parts, before putting the parts together. When working with bigger parts, you'll always want to tin them first.
Any time you strip a braided wire, I recommend tinning the end. It helps it hold in almost any kind of connector, even crimp connectors. If putting braided wire into a screw down or clamp terminal, I consider it a "must" to tin the ends. The solder is nice and solid to squeeze against to prevent the wire from pulling out, yet soft enough to deform a little to the shape inside for good current flow.
1. My variation of tip cleaning is a bit easier to come by then some fancy paste.... I just use fine sandpaper. The tip really shouldn't have any black stuff on it. I occasionally use my iron for melting plastic together, and that stuff needs to be gone before soldering again. Just run the sandpaper lightly around the tip to get it shiny. Do this with it cool.
2. Maintaining a clean tip with a wet sponge like in the links above really does help. The second link mentioned a wet paper towel works just as well as a sponge. I use anything for a rag I have laying around, or even some old leather work gloves (which don't need to be wet). It really doesn't matter what it is. You use this when the tip is hot.
3. The parts we play with are exposed to the weather, and this effects solder-ability. If a wire is at all corroded (a little bit green or black in color, or not shiny), solder will NOT stick to it. Just about the time you think you got it, it falls apart. And I haven't found a way to clean it. Avoid the frustration, cut the wire back til you get to better wire, or replace the wire.
4. Tin the tip of the iron. This is a VERY thin coating on the entire tip, wipe off or shake off the excess (be careful where you "fling" it!).
Right before touching the iron to a part, add a dab of solder on the tip. This will help a LOT with heat transfer. In fact, I don't recommend trying to heat a large part without a dab of solder on it. Having a dab of solder also helps for un-soldering larger parts.
Make sure the iron is hot enough to melt the solder before touching it to any parts. If it's not already hot, it's not going to get hot because the part will be pulling heat away as fast as it's trying to heat up.
5. Tin the stripped area on the wire.
I usually set the iron on the table for this. Hold the wire in one hand, solder in the other. Touch the wire on the iron, and immediately start feeding it solder. Keep the wire touching the soldering iron in the same place, but move along the wire with the solder. It should continue melting even away from the iron. Continue until all the stripped area is covered. Try to move quickly, the insulation will melt, and eventually you'll burn the fingers you are holding the wire with!
- If the wire has to fit into something, a "crimp" connector for example, you'll want just enough solder to fill between the wires, but no blobs. You can shake off or wipe off (wet rag) the excess while it's hot.
6. Soldering a wire into a crimp connector.... Find something to hold the connector. A vice or vice grips will work, but try to clamp as far as possible from the area to be soldered, as the holder will suck out a lot of heat. Hanging it on the wire doesn't work too well.
Slip the tinned wire into the socket. Crimping it shut is optional, I've done both ways.
Touch the soldering iron to the connector only, and start "trying" to apply solder, a dab at a time. It may take a second to heat the connector enough to melt sodler into it, but having a drop of solder on the tip of the iron helps transfer heat into it. Once it starts flowing, try to fill the void up solid. BUT, be careful to not allow solder to run into the "connection" area, or it won't go together later and you'll have to cut the connector off and start over.
6. Soldering a wire to a "part" or "tab"....
It's relatively likely you'll melt the plastic in the switch or the plastic insulator around the tab on the motor. I do not solder to them, I solder the wire to a female spade and slip that on the tab. But, if you really must solder to the tab......
Tin the tab, but do it as quickly as possible. Touch the hot iron on it, immediately feed solder, get a nice size blob on it, and pull heat and solder away. The goal is to not have to add solder when you put the parts together, because feeding solder takes one more hand then you have available.
Secure the part that has a tab on it (clamp a switch in a vise, or bolt a motor to a gearbox). This way you have the soldering iron in one hand, wire in the other. Hence saying there's no free hands to feed solder!
Again, have a dab of solder on the tip of the iron. Touch the wire to the tab with a slight amount of pressure. Touch the iron to the wire. It should melt together almost instantly. As soon as it puddles, the wire should drop to where it needs to be, and immediately remove the heat. Try to hold the wire steady as it cools. Blowing on it actually does help it cool faster. Being quick will help prevent heat damage to the part.
7. Soldering wires together....
Sure, there's other ways to splice wires, but soldering them is almost a gaurantee of a good connection, good current flow, etc.... and is actually pretty fast.
Tin each wire to be connected following directions above, but make sure you have a decent blob of extra solder on both.
If doing 2 wires, I set the iron down, and hold a wire in each hand. Touch them together, and touch them both on the iron. As soon as they melt, pull them off the heat without pulling them apart. The joint won't lay perfectly flat, so adding insulation can be tricky.
8. Insulation... Once done soldering, there's exposed parts that you may want to insulate.
Heat shrink tubing works for most things, but may need to be semi large to fit over some of these connections.
Plain ole' vinyl electrical tape works, for a while. Rubber electrical tape stays better, but is a pain to put on correctly (needs to be stretched), and is almost impossible to get off.
A couple coats of liquid electrical tape actually works pretty well, nice and neat looking, will cover any shape, more water tight then the other options, etc.
With any of these methods, watch for stray strands of wire that may poke through the added insulation.
FREE is always better.