I’m going to install a new car stereo receiver, and instead of crimping the harness wires together like I usually do, I’ve decided to solder them. I think the wires are 18 gauge, and each connection will just be a splice of two wires. My question is, what wattage soldering iron/gun should I buy? I’ve never soldered before, but I have an idea of how to do it, but I don’t know how many watts will be sufficient for this kind of work. TIA!
–FCOD
Having been a technician for more than twenty years I feel that I should be able to answer this question. The problem is that I haven’t seen a regular, wattage-rated soldering iron in more than a decade. The ones we use now are high tech sophisticated ones that just about do the soldering all by themselves. I can tell you that you might as well get a pretty high wattage one. The low watt ones are for tiny delicate work. Soldering wire together is anything but delicate. Go for the 800 watt jobber. If nothing else, it will make the work go faster.
Thanks for your advice.
I discovered a 30-watt iron in my computer repair toolkit that I didn’t know existed. Is it even possible to do what I described with an iron like that?
–FCOD
Are you kidding about the 800 Watts, or was that a typo?
For soldering two 18 guage wires I’d use the 30 watt iron. The main reason for using, say, the 15 watt iron is if you are trying to solder integrated circuits or other delicate components and don’t want to fry the innards.
With two wires you don’t really care about frying anything, although if you transfer too much heat you’ll start to burn the insulation.
The main thing I’d say with the 30 watt is to have a little patience, and to make sure the soldering iron tip is on firmly. Other than that I like to keep the tip clean by actually rubbing it on some sandpaper.
Yeah, they sell cleaner and all that but the tips cost less than 10 bucks and I can wipe them off when using them so I use the sandpaper.
Otherwise if you get the black crud on the tip it won’t heat worth anything.
As for the new ‘cold’ soldering irons - it looks to me like they work by actually using some sort of electrical current to heat the solder and not the tip itself. If you work quickly then the ‘tip’ won’t get too hot and won’t burn you. I think they are mostly a gadget and I prefer my old fashioned low tech iron.
What about a soldering gun? Well, maybe, if you’ve got a ton of things to solder, but they are bulky and you might get tired of waving it around. I think they are overkill for soldering stereo wires, but they’d do the job.
None of this is rocket science, and you won’t be graded on it. Have fun and see what works for you!
That will prolly work*. You might have to be patient and give it time to heat the wires. You’ll just have to try it and see. Twist a couple of your 18 ga wires together and apply the heat to them. Give it a few seconds and then touch the solder to the wire. It should flow freely throughout the entire connection. If it doesn’t flow, then there isn’t enough heat.
I have a 100/140 watt soldering gun, and its low setting is more than enough for what you want to do. 800 watts is major overkill, and would be extremely hard to control for that task, likely doing some damage. Your 30 watt iron may be up to it, just try it on some test wires and see how it does.
Be sure to use resin core (electrical) solder. For this type of work, the skinny stuff (1/32") is more suitable than the more common 3/32" thickness.
Using heat shrink tubing rather than electrical tape over the joints will result in a neater, more secure covering, and is easier to boot.
800 watt soldering iron? :dubious:
A 30 watt soldering iron will do the job. You can also buy “solder tape” that you basically wrap around the wires, light it with a match or a cigarette lighter, and call it a day.
For a car stereo, you may find that crimp connectors work better. When you make a solder joint, you’ve got copper, lead, and tin all mushed together, and they all expand and contract at different rates. In a crimp connector, the elesticity of the metals handles the expansion and contraction. In a solder joint, the constant temperature changes will eventually cause the solder joint to weaken and make a bad connection.
Use a wet sponge to clean the crud off of the end of the soldering iron, not sandpaper.
Also, heat the wire, not the solder. You want the solder to flow onto the hot wire and make a good connection. Globbing hot solder onto cold wire makes what is called a cold solder joint, and is very prone to failure.
Those “cold heat” soldering irons are junk.
Thanks everyone. I assumed the 800 was meant to be 80…but I’m glad to hear that the (free) 30 watt iron should work. I’ll pick up some heat shrink tubing today.
I’d rather not crimp the wires because I’ve had bad luck with the connectors falling off the wire…this should be more secure…I think.
Thanks again!
–FCOD
I guess I accidentally bumped my brain into neutral there for a minute. I had glanced into the cabinet where we store the replacement tips. They are rated by tip temperature. Some of the highest rated ones are 800 degF. Somehow that came out as watts though.
Well, you said you used industrial stuff, so I thought maybe there was an 800 watt iron. I bet that sucker would heat up in a hurry! Might trip your circuit breaker, too, depending on what else was turned on.
But, like you said, it would make the work go faster. It could probably solder a couple wires in a tenth of a second or so. I wouldn’t want to be holding onto the wires, though!
And, yeah, you can use a wet sponge to clean the tip, but then you don’t get the nice shiny base copper exposed, and you don’t get to see how long you can rub the sandpaper against the tip and not get burned.
Like I said, have fun but use protection.
Well, you said you used industrial stuff, so I thought maybe there was an 800 watt iron. I bet that sucker would heat up in a hurry! Might trip your circuit breaker, too, depending on what else was turned on.
But, like you said, it would make the work go faster. It could probably solder a couple wires in a tenth of a second or so. I wouldn’t want to be holding onto the wires, though!
And, yeah, you can use a wet sponge to clean the tip, but then you don’t get the nice shiny base copper exposed, and you don’t get to see how long you can rub the sandpaper against the tip and not get burned.
Like I said, have fun but use protection.
This is so obvious that nobody has said it, but if you’re a newbie at soldering, remember to use the iron to heat the wires, and use the wires to melt the solder. Don’t melt the solder against the iron. If the wires aren’t hot enough to melt solder, then the molten solder won’t stick to them.
We do have a couple of truely monstrous irons around here somewhere. The tips are 1/2 square copper bar with a chisle tip. I’ve never seen anyone actually use them for anything though.
Yeah, but the soldering iron tip is not just any old chunk of copper. It has to be properly tinned in order to work correctly. Sandpaper takes the tinning off and the tip never does function the same thereafter. This is a little nit-picky when we are discussing the soldering together of large gauge wires but, there ya go.
This sounds like a good idea, but seems not to produce consistent results. You allude to what is probably the main reason:
If you’re skilled enough to make solder tape work reliably, you’re probably also smart enough to use a soldering iron.
A properly soldered joint will be quite secure. That includes twisting the wires together a bit for a mechanical connection, and as mentioned making sure the wires are hot enough to melt and flow the solder.
A properly crimped joint is also quite secure. That includes using the right size connector, using a crimping tool with the right jaw design, and squeezing that puppy really tight.
If you’re not familiar with heat shrink tubing, keep in mind that it will need to fit over the soldered joint, which will be thicker than the wire. The idea is to use the smallest diameter tubing that will go over the work. If the solder joint is too bulky, the tubing that fits it might not shrink enough to hug the wire, so try to keep the joints trim.
[nitpick]I believe it’s usually called rosin (it is indeed a pine resin).[/nitpick]
Very true. Most beginners make soldering a lot harder than it needs to be by using a tip and solder that are fatter than necessary.
True. But you can seriously improve heat transfer with any tip by using a small droplet of solder: iron heats solder, solder heats wire.
Do they come with two extra hands? I’ve done a touch of soldering in the past, but always seem to find myself a couple short. You need one hand to hold the iron, one to hold the solder, and one for each of the pieces you’re connecting, and my toes aren’t that flexible.
Why would you ever want to do this? It’s a bad idea. It’s much easier to make a good crimp connection than a solder joint!
Professional electricians, auto mechanics, etc. almost never use solder connections any more. There’s good reason for that.
[QUOTE=FlyingCowOfDoomI’ve never soldered before[/QUOTE]
Then even more reason to avoid trying to do that.
Your time would be much better spent on learning how to do better crimp connections than on learing to solder.
Really? I already know how to crimp wires, I just don’t have to appropriate tools.
I guess I’ll just keep doing things the same way forever and hope I never come across a situation that requires me to do something I’ve never done, because there’s obviously no way I’ll succeed in learning a new skill by trying.
I’m shocked to hear that a crimped connection is sturdier than a soldered one…but I’m still going to solder the harness.
–FCOD