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Old Nov 10, 2012, 03:32 PM
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Soldering hints

First - don't be trying to solder any of the wires on your heli with a big Weller 100 watt gun style. You won't be able to do it.
Get a small pencil iron. No more than 60 watts - max.
Radio Shack has a "starter kit" for $12.00
http://www.radioshack.com/product/in...ductId=2062758

Second - get "rosin core solder". The smallest diameter they sell. Not the huge stuff from Home Depot for plumbing.
Rosin is flux inside the solder. It helps deoxidize the copper as you solder.
Get leaded solder if you can find it. It's much easier to work with than the lead-free: http://www.radioshack.com/product/in...ductId=2062719
(you probably won't be able to find leaded solder in Europe).

Let's assume you're soldering two wires together.

"Tinning" means getting some molten solder on to something - either the soldering iron tip, or the wire.
You want the solder to "plate out" (coat the surface like paint and fill in between the strands).
You don't just little balls clinging to your work. That won't work.

1. Get the iron hot (should only take 2-3 minutes).
Make sure there is some solder on the tip.
Clean it with a damp sponge (while hot).
"Tin" the tip. Which means adding enough solder to coat it and make it shiny.
Wipe it again on the sponge.
Repeat until it stays shiny.

If it's really tarnished (it's probably copper). You may need to clean the tarnish off the iron before it's usable.
You can use sandpaper or a file to expose fresh shiny copper.
Tin it right away to keep it from tarnishing again.
Before you put the iron away, tin it one more time, and wipe it with the sponge. Ready for next time.

NOTE: If the iron cost you more than $20, the tip may have a special coating.
DON'T sand or file it off. Especially if you borrowed it from a friend...

2. Strip the wires a little longer than you think the joint should be. Maybe 1/4"

3. Tin each of the wires separately. Meaning get just enough solder to fill in the twisted wire, but not enough to make blobs.

4. Just before soldering anything, add a bit of solder to the tip in the area that you're going to contact the wire or whatever. That allows heat transfer.
Without this important step, you won't get heat transfer.
Think of two ball bearings touching. Very little contact area.
Add a little liquid metal to one and voila. Lots of contact area for heat transfer.

5. Then heat the wire and apply solder to the wire near where the tip is touching it.
Don't keep pumping solder onto the tip.
The solder has flux (mild acid which cleans the oxidation from the wire) and if you apply it to the tip it burns off before getting to the copper.

6. Repeat for the other wire.

6. Twist the wires tightly together.

7. Solder them together. Heat one until the solder melts. Apply a little solder and it should flow to the other wire.

8. A good solder joint (with leaded solder) should be shiny. If it looks "grainy", it's a "cold" solder joint and will probably crack. Not enough heat causes cold joints.
With lead-free, it's hard to tell. They always look grainy And they often break.

9. Trim the joint if it's longer than you'd like.

10. If you get too much solder on anything during the process, you can usually wipe the iron tip, then touch it to the wire and it will suck some of the solder off the wire.

Don't be afraid to get some wire and practice before doing your actual job.
Whatever wire you have sitting around.
Speaker wire, old electrical cord...
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Last edited by RicksterRC; Nov 10, 2012 at 10:56 PM.
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Old Nov 10, 2012, 07:40 PM
KDS450QS(ZYX4),V977,CX-20
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United States, CA, Monterey
Joined Apr 2012
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Flux?

I am very glad to read this. I can't solder properly. I don't know why. The solder doesn't stick to the intended target material. Then I read... I need to apply "flux", some brown paste. I've ordered a tub and hopefully I can join two wires together. I spend hours on soldering, which seems ridiculous to me as others do it in a few minutes.

You left out flux in your post. I wonder if it is necessary to solder two wires together. On mine, the solder just doesn't stick. Very frustrating!
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Old Nov 10, 2012, 10:50 PM
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Quote:
Originally Posted by FyreSG View Post
I am very glad to read this. I can't solder properly. I don't know why. The solder doesn't stick to the intended target material. Then I read... I need to apply "flux", some brown paste. I've ordered a tub and hopefully I can join two wires together. I spend hours on soldering, which seems ridiculous to me as others do it in a few minutes.

You left out flux in your post. I wonder if it is necessary to solder two wires together. On mine, the solder just doesn't stick. Very frustrating!
Do you use rosin core solder? It has a center of flux. It's usually sufficient unless the wire is badly corroded.

Solder won't stick to corroded copper. You'll just end up with "balls" of solder that refuse to penetrate into the wire strands.

Think of water droplets on your freshly waxed car.
Then think of how soap makes the water spread out.

Flux is a mild acid that - when heated - dissolves corrosion on copper wires and allows the solder to stick (plate out).

I have a bottle of liquid flux with a brush I got years ago. I use that when needed.
I find the paste is too difficult to use. You get too much on - it's just a mess.

With larger gauge (diameter) wire that's badly corroded (like the wire for my landscape lighting), I sometimes gently scrape the exposed strands with my pocketknife to exposed shiny bare copper. That's usually sufficient to get some solder to penetrate. Once you get some in, the flux starts working.

It takes practice.
I'm an electrical engineer. I've been doing it for 35+ years and I still burn my hands and mess it up miserably some times.
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Old Nov 11, 2012, 07:46 AM
KDS450QS(ZYX4),V977,CX-20
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United States, CA, Monterey
Joined Apr 2012
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I have no idea what's the solder I'm using. It's cheap stuff I got from a local store. Most of the time, it doesn't even stick to the soldering iron tip! Once the solder touches the tip, it melts and trickles down. I had to balance the ball of melted solder on the tip then quickly flip and dab on the desired wires.

I have difficulty soldering magnet wires to 5mm LED pins. All are new, no corrosion. I hope getting the flux will help.

I also had problems soldering oxidized wires to a plane motor. I doubt flux will help here, so I'll try to find new wires.

Yes, practice. You've been doing it for years while I just started learning about soldering.
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Old Nov 11, 2012, 07:38 PM
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Quote:
Originally Posted by FyreSG View Post
I have no idea what's the solder I'm using. It's cheap stuff I got from a local store. Most of the time, it doesn't even stick to the soldering iron tip! Once the solder touches the tip, it melts and trickles down. I had to balance the ball of melted solder on the tip then quickly flip and dab on the desired wires.

I have difficulty soldering magnet wires to 5mm LED pins. All are new, no corrosion. I hope getting the flux will help.

I also had problems soldering oxidized wires to a plane motor. I doubt flux will help here, so I'll try to find new wires.

Yes, practice. You've been doing it for years while I just started learning about soldering.
You can see the rosin core in the solder if you look at it with a fairly strong magnifying glass. Brown pasty stuff.

Sounds like your soldering iron tip is all gummed up/corroded.
You need the solder to "coat" the tip. If it balls up, it's like an oxidized wire. Won't work well at all.

You can try cleaning it by dipping it (hot) in the flux when you get it, but you're probably better off cleaning it with sandpaper until you expose bright shiny copper.
Sand it while cold. As soon as it heats up, quickly coat it with solder (before it oxidizes again).

For magnet wire, you have to gently burn off the insulating varnish like stripping the wire.
Put a little solder onthe tip and immerse the end of the wire in it.
When the wire ends up shiny silver, the varnish has been burned off and the wire is tinned.

If you have the money, I'd suggest considering getting a new iron and some fresh solder.
Might end your frustrations!
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Old Nov 11, 2012, 09:26 PM
KDS450QS(ZYX4),V977,CX-20
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United States, CA, Monterey
Joined Apr 2012
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I'll examine the solder tonight but I doubt it has rosin core. It's really cheap - one cylindrical coil of solder for less than USD1.00 from a neighborhood shop.

Can you clarify the steps to clean the soldering tip? It's not about the cost but I like to use things until they are really not usable. So after sanding it, I'll power it on, let it heat up, poke into the tub of flux, then "coat with solder"? What's the last step?

I suppose after doing all that, I'll power off the soldering iron and it'd be good to use the next time.

Thanks for the information!
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Old Nov 12, 2012, 02:22 AM
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Originally Posted by FyreSG View Post
I'll examine the solder tonight but I doubt it has rosin core. It's really cheap - one cylindrical coil of solder for less than USD1.00 from a neighborhood shop.

Can you clarify the steps to clean the soldering tip? It's not about the cost but I like to use things until they are really not usable. So after sanding it, I'll power it on, let it heat up, poke into the tub of flux, then "coat with solder"? What's the last step?

I suppose after doing all that, I'll power off the soldering iron and it'd be good to use the next time.

Thanks for the information!
Sand or file till shiny copper.
Then you should be able to apply the solder and have it "plate out" - like a coating of paint.
The tub of flux might help clean it. It will make nasty smoke that will make your eyes sting
And after dipping in the flux, you should wipe the tip on a damp sponge to get the burned flux off.

Once you get the nice shiny coating on the iron, your're ready to go.

Put some flux on the first wire, add a tad of solder to the tip (for that increased contact area). Put the iron on the wire. Wait for the flux t o smoke.
Add a tiny bit more solder to the tip and wait for it to get sucked onto the wire.
Add solder to the wire until the strands are filled.
Do to both wires, twist them together and do it one more time. Like two big strands.

Before putting the iron away, make sure it has a shiny silver coating of solder to keep it from corroding before next time.
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Old Nov 12, 2012, 02:29 AM
KDS450QS(ZYX4),V977,CX-20
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United States, CA, Monterey
Joined Apr 2012
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Thanks for the tips. I thought soldering was as simple as putting solder on a soldering iron. I was dead wrong! I guess I ruined my soldering iron with poor care. I'll take note of the smoking flux and stay clear of it.
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