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Soldering Question ... Something I've Always Found Very Challenging

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Posted by MOAVBILLY on Sunday, July 11, 2010 12:15 AM

Something to consider also is the mechanical connection between the soldering tip and the barrel of the iron. I have two different types, one the tip screws into the barrel and one uses a small screw to retain the tip. Before plugging in the iron, I always either back off the screw in tip and retighten or loosen the screw and rotate the tip. This assures a good "bond" for heat transfer from the heating element to the soldering tip.

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Posted by db200 on Friday, July 9, 2010 1:12 AM

I used to be a certified solder instructor for the US Army at a rather large Army base. Around 1996, the Government, in its inifinite wisdom, closed the four DOD Solder certification schools. So, it's been a while since I taught soldering, but I have continued to provide advice and support to various US Army Programs for assembly and soldering of electronic equipment that the Army purchases for our valiant troops.

I have provided that little bit of my background so that you'll know that I know what I'm talking about. It's sad to me when I see this topic come up in a forum because the people that respond are genuinely trying to be helpful, but so many times, they don't know what they're talking about. It's not that they're doing anything intentionally wrong; it's just that they have never been taught and so one never knows what to believe when reading the responses.

So, let me give you my 2 cents worth:

1) You do not need three hands to solder. What you need is to properly set up your work. If you're right-handed, your right hand will hold the solder iron and your left hand will hold the solder wire (and vice versa if you're left-handed). Set up the two pieces you're wanting to solder together so that they do not move in relation to each other. You can use any type of vice or clamp that you have available. For example, when I splice wires together, typically one of the wires is already attached to a part, but the other wire is not - it's hanging free. So, strip the wires and form two U-hooks so that they 'hold hands' with each other, and then use a clamp or some other method to hold the free wire. The key here is to put the 'free' wire under tension so that the wires don't move when you touch them with the solder iron.

Let me try to describe how I prepare a feeder wire. After drilling a hole in the roadbed, insert the wire from underneath and strip the wire.(After playing with this for a while, you'll figure out about how much insulation to strip off.) Make two 90 degree bends in perpendicular planes in the wire. Coming up vertically through the roadbed, the wire should make a 90 degree turn toward the rail (this covers the distance from the hole to the rail) and then make another 90 degree turn parallel to the rail (this is the part of the wire that gets soldered to the rail.) It just so happens that 22 ga solid wire almost perfectly fits the web of Code 83 HO rail. I found that after getting it in position, I can slightly push the wire up from underneath while holding it against the rail with flat-nosed pliers so that it stays put and doesn't move when I get ready to touch it with the solder iron.

2)  ALWAYS make sure that the two metal pieces being soldered are clean! For feeders, I always clean the web of the rail with the wire brush head of a Dremel tool. I never re-use old wire. New wire is generally pretty good and solderable.

3) The amount of flux contained in rosin-cored solder wire is usually all you need - especially if your pieces are clean and solderable (see #2 above). The only purpose flux serves is to prevent the two metal pieces you're soldering from oxidizing during soldering. That oxidation is what will prevent good wetting action, and good wetting is indicative of a strong solder bond. Extra flux will never overcome dirty parts. I usually only use (extra) liquid flux when I'm reflowing a bad connection or wanting to completely remove solder from a connection, such as during disassembly of soldered parts.

4) Heat Control. This is another area of great misunderstanding. So, I will try to describe everything that you must consider:

a) Use a tip that is the correct size for the parts being soldered. A tip that is too large for your work will only lead to overheating and damage. Conversely, a tip that is too small will never get anything hot enough.

b) Set the solder iron to the proper temperature. What's the proper temperature? It's whatever gets the solder flowing without overheating, so you'll just have to try different settings on different parts to find out what works best for you. My rule of thumb is to solder small parts at a setting of 650 deg F, medium parts at 700 deg F, and larger parts at 750 deg F.

c) You are correct that the sponge provided with your iron is there to clean the tip. Here's what you should be doing. Wet the sponge with cool (not cold!) tap water and then wring it out so that it is damp (not wet!) to the touch. When you're ready to solder, wipe the tip on the sponge and the tip should be a bright silver color. Don't wait too long, because the tip will turn brown from oxidation and you'll have to re-tin it.

d) Place your solder iron so that the tip makes contact with both pieces being soldered at the same time. If one piece is larger than the other, (such as a rail vs. a feeder wire) then place the flat blade of the tip against the rail, while at the same time making contact to the wire with just the tip of the iron. That will transfer more of the heat to the rail. The key to controlling the heat is to make sure BOTH parts are heating up simultaneously. Once you have placed your solder iron against the two parts, DO NOT move it. Leave it in that spot for the entire process.

e) Next, (THIS IS THE IMPORTANT STEP) you need to form what we in the industry call "The Heat Bridge". Place the solder wire at the junction of the rail, the wire, and the iron tip. The idea here is to get the solder flowing. It may take a second or two or five, so be patient. Once the solder starts flowing to both parts, then you know the parts are hot enough. When the solder starts flowing, immediately move the solder away from the iron tip. You can now 'paint' the connection with solder to get it in between all portions of the connection. Also, the liquid solder will flow back towards the iron tip, since solder always flows towards the heat source. This helps the solder go where it needs to.

f) When you see that solder has flowed into all the crevices of the connection, remove the solder wire FIRST. Once the solder wire has been removed, THEN remove the solder iron from the connection. Try not to move any part of the connection as you remove the iron or after removing the iron. The solder will remaind liquid for a few seconds until it cools, and if anything moves, the conncetion could be damaged.

g) Last step. Before turning the iron off, protect the tip by touching the solder wire to the tip so that a small bead of solder remains on the tip after it has cooled down. So the next time you turn the iron on, the bead will be there and can be wiped off at your next attempt at soldering.

I hope this short tutorial has helped!

 

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Posted by nscsxcrrailfan on Thursday, July 8, 2010 8:40 PM
Actually, you can disregard my first question. I went back and saw that you already answered it in your previous post.
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Posted by nscsxcrrailfan on Thursday, July 8, 2010 8:37 PM
O.k., without my new pen shaped tip, for the time being I am limited to my large screwdriver shaped tip. I tested out your procedure and here are the results. First, it is difficult for me to keep the iron tip tinned on any setting above 3 1/2. The solder just boils down to almost nothing on the tip and has little heat transfer ability. At 3 1/2, I can keep the tip tinned for a little while before I have to clean the tip again and reapply a little solder. The RadioShack tinner/cleaner does a good job of tinning the iron's tip, but even it loses effectiveness rather quickly after I turn the iron above 3 1/2. FIRST QUESTION: What does a good tinned tip look like? Does the whole tip have to be covered in solder or is it o.k. for a small drop to be on the end to transfer heat?? Next, I tried the method you suggested for soldering to the rail. I turned the iron on 3 1/2. I used a test piece of track, which wasn't secured so I modified your procedure slightly. I tinned the wire along with the bead of solder on the iron's tip. Between the two, I have all the solder I need without adding any more. I added rosin flux to the spot on the rail where I was going to install the feeder. I touched the tinned wire to the flux and applied the iron't tip, specifically the side of the tip where the bead of solder was. I held it on there for 4 seconds. The ties did melt some, but it didn't look too bad. I tried the same procedure at 3 seconds and still got a couple of somewhat melted ties. I lowered the temperature dial down to 3 (exactly half) and kept the iron on there for 3 seconds. The ties still melted but not very much and less often. I tried using wet cotton balls on both sides of the joint which helped a little, but they did not keep the heat from getting the two ties right below the solder connection. I figured out that if I lightly press the wet cotton ball to the ties directly after moving away the iron, it seems to lessen the melting some. The main thing I have been concerned and worried about, as you could tell, was the likelihood of creating cold solder joints using this method. I didn't know if the hot bead of solder hitting the rail/flux actually pushed enough heat into the rail to create a good joint. So, to put my fears to rest, I performed a test of my own. I used the procedure above (setting 3, hold 3 seconds) and pushed a piece of solder against the rail on the inside of the rail, directly on the opposite side of where I was soldering. I held the iron on the outside of the rail for 3 seconds while the bead of solder, flux on rail, and solder on wire fused together. Exactly on the third second, the solder on the other side of the rail melted very fast and adhered very tight against the inside of the rail. I repeated this test several more times. Holding the iron on there for 2 seconds does not result in the solder melting on the inside part of the rail, but holding the iron on there for 3 seconds does melt it. Therefore, I have put my fears to rest on this issue. This method does indeed heat the rail hot enough to melt the solder without creating a cold joint and without having to use a big 100 watt gun to heat the entire rail. SECOND QUESTION: Does the burnt black flux left on the solder connection cause any problems? I don't encounter it very often in making rail connections, but I have noticed that when I try to get solder to melt onto wires twisted together that I sometimes encounter burnt black flux that won't come off. Adding more solder to the spot seems to just cause it to deflect and flow past the spot. Any thoughts?
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Posted by modelmaker51 on Thursday, July 8, 2010 2:03 PM

The Tip Tinner and Cleaner you got is the right stuff, thats what I use, It used to come in a can about twice that size, anyway, I stick it right to the top of my soldering station, (there's foam tape on the bottom of the can). Tinner/Cleaner is essential for good soldering.

Don't stick the the iron in the flux, that'll start to build up crud on the tip. Instead, to start a soldering session, let the iron get hot, (with code 55 rail try setting 4), then dip the tip in the Tinner/Cleaner, (the stuff is hard like soap), let the tip melt it's way to the bottom of the can and give it a couple of twists and wipe it off on the sponge, melt a pretty good glob of solder on it and put it back in the Tinner/Cleaner, twisting it again and then wipe off the extra solder with the sponge. If the solder is evenly distributed around the tip and nice and shiny, your tip is properly tinned and cleaned, if not repeat the process. As you use the iron, areas on the tip will start to show black and/or the solder beads up on the tip instead of flowing on, it's time for a quick dip in the cleaner and a wipe on the sponge. Allways wipe the tip on the damp sponge before and after each solder joint.

Forget about flux in the solder, as long as it doesn't say Acid Core. What RS sells is all electronics solder, so it is either rosin core or solid core (no flux, we apply the flux to the work anyway, so it doesn't need to be in the solder). both of which are fine for our purposes.  You only have to be concerned about the core when you buy solder at hardware stores where they sell both rosin (for electrical) and acid (for plumbing), so don't buy solder in the plumbing department!

Jay 

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Other builds: https://imageshack.com/my/albums 

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Posted by richg1998 on Thursday, July 8, 2010 11:57 AM

 I went to the RS site and did not see anything about flux in the solder. When I have used the same solder I dipped it in a little RS flux before soldering. Since the solder is in paste form, I put the iron tip in the flux and melt a little into a puddle. I have some RS liquid rosin flux but they stopped selling it.

IMPORTANT, practice with scrap track/wire. Remember, new does not always mean clean and ready for soldering when it comes to track or copper PC boards unless the PC board was already plated with a solder film. Develop a technique that gives you the results you want.

I use a Scratch Brush from Micro Marks to clean a spot of the track for soldering.

Anyone tells you soldering is easy, they have been doing it for sometime. Also applys to those who tell you that you do not need all the stuff I mention.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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Posted by nscsxcrrailfan on Thursday, July 8, 2010 11:13 AM
O.k., just to be on the safe side I went ahead and also ordered ST5. I'm throwing everything I have at this; hopefully once the tips arrive, I'll be able to finally do some good soldering.
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Posted by nscsxcrrailfan on Thursday, July 8, 2010 11:10 AM
I just ordered the ST6 tip instead of ST5. According to Weller's website, the ST5 tip has a flat top, whereas the ST6 tip has a screwdriver top. I figured that would be better. The diameter of my current tip is .187", and the ST6 tip is .031" in diameter. Hopefully it will do a much better job.
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Posted by nscsxcrrailfan on Thursday, July 8, 2010 10:54 AM
I went to my local RadioShack store today and bought the smallest size solder I could find. I bought 62/36/2 Silver-Bearing Solder at .015" diameter. It doesn't say whether or not it includes rosin flux; I assume it does. If it doesn't, can I just rely on the external source of flux? Also, I bought the RadioShack Tip Tinner and Cleaner. It's a little small metal container with a metal lid that pops off. Also, I'm going to order a new tip for my soldering iron. The conical tip I ordered a year ago was ST7. I didn't mention this earlier, but the only way I can avoid building up a massive amount of heat near the handle with it was to reduce the heat to the 1-2 setting (approx. 10-15 watts). That obviously wasn't enough to get the job done. They make two other pencil shaped tips for my soldering iron, ST5 and ST6. I'm going to try ST5. Here's a question. My soldering station is between 5-40 watts. If I replace my screwdriver tip with a pencil shaped tip, what setting should I have the iron set to between 1,2,3,4, or 5?
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Posted by modelmaker51 on Thursday, July 8, 2010 4:08 AM

I use Radio Shack .022 diameter (62/36/2) rosin core Silver-Bearing solder. There's a little silver in it to make it stronger and it will not corrode over time. It's made for electronic circuitry, but it works great on track and just about anything else. The thin diameter heats up quickly and gives you more control, (you don't end up with big blobs where you don't want them)

Another tip on stabilizing the wire so you don't need the "third" hand, after inserting the wire thru the hole in the benchwork if the zig zag bend doesn't work just wedge something in the hole to keep the wire from moving.

Here's my process: 

Add a little dollup of flux where I want it and then position the wire against the rail so I'm all ready to solder. I extend about 3 or 4 inches of solder from the roll, give the iron a wipe on the sponge and then touch the solder to it, feeding about 1/4" to 1/2" (of the solder wire) to the tip (the pre-load), enough to get the join started, (but you don't want a big blob on the iron). Position the solder right up by the joint (but not touching) and then bring in the iron and touch the joint, as the flux starts to sizzle (about a second) feed about 1/2' of solder into the joint right where the iron is touching the joint, pull the solder away keep the iron on there for another second or so and pull it away. You should be able to do it on a count of four. One (touch with the iron), Two (add solder), Three (remove solder), Four (remove iron), total time about 2.5 - 3 seconds. (My quantity (in inches) of solder is based on the .022, if you use .032 use a little less). Practice this with the count and you should get the hang of it, oh yeah, start the count once the iron touches, not before. For practice, pull a couple of inches of ties off the track, do the routine several times with just the counting, don't worry about the actual time, it'll get faster as you get the hang of it, after about a dozen times you should be doing it in about 2-3 seconds, then try it on a section with ties. Good Luck.

You can fix cold joints easily. First make sure the wire isn't going to move when you melt the solder, then add a dab of flux, wet the iron with some solder just as you would for a new joint and then touch the joint for a couple of seconds (about a 3 count) and remove the heat. The join should look nice and shiny, if it isn't, let it cool completely, before you give it another try or you will melt the ties.

Forget about the flux in the solder, there's only enough to get the solder to flow onto the iron or for tiny joins like circuit board work, for everything else you add flux, liquid flux (like TIX brand) works well too and is less messy. Flux (rosin flux that is) won't hurt anything, but it should be cleaned from the join after soldering as paint won't stick to it, (if you're going to paint your rails), a brush and some alcohol will do it.

The paddle tips are best suited for soldering wires together (splices).

 To the poster who only solders the wire drops to rail joiners, you will still end up relying on the friction fit of the rail joiner to make and keep the electrical contact, over time time you may not find that to be so reliable as the joiners can work themselves loose because of heat and humidity. The point is that long term, rail joiners should only be relied upon for the mechanical connection, not the electrical. A better way if you want to completely hide the drops is solder them to the bottom of the rails before you lay them.

 Sorry about my lengthy and overlapping posts, Jay.

Jay 

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Other builds: https://imageshack.com/my/albums 

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Posted by nscsxcrrailfan on Thursday, July 8, 2010 1:40 AM
So basically it is fine to pre-load the tip with solder, but I need to make sure and use flux and let the iron stay on there for 1-2 seconds to bring the rail up to the temperature of the solder. There are a few things that I am going to immediately change about my soldering method. First, I'm going to replace the original screwdriver tip on the iron with a small pen shaped tip. Believe it or not but I actually ordered a cone-shaped replacement tip about a year ago because everyone recommended getting away from the large screwdriver tip that I've been using. However, I ordered the wrong one, and it was hollow inside. What it did was build up a tremendous amount of heat near the handle of the iron, which got so hot that the metal rod extending from the handle started to turn clear where I could see the coil running inside the iron. In addition, that part of the iron turned an ugly purple/black color. I immediately took that tip out of there and went back to the original. I'm going to try and get the right one this time. Also, many people have recommended using 60/40 solder in the smallest size possible. I've been using .032 diameter, but a friend of mine uses solder even smaller than that for N-scale. Also... I'm going to try the wet cotton ball technique of placing two wet cotton balls on both sides of the soldering location. One final question: So basically it's o.k. to pre-load the tip as long as one uses extra rosin flux and holds the iron on there for 1-2 seconds. Now, my question is, I've been pre-loading the tip without holding it on there for any length of time at all because I've been afraid of melting ties. Are my joints likely not strong enough (cold joints)? Can I simply re-heat them to fix this or should I not worry about it?
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Posted by modelmaker51 on Thursday, July 8, 2010 1:26 AM

The flux that is in the solder just isn't enough flux, if you pre-load the tip (which is what I do) then the flux that was in the solder has already evaporated and burned up, so you need to add the flux at the joint.

"I don't understand why the hot solder hitting the rail and flux would not create a good joint due to the fact that the solder has sat on the iron for several seconds and is already heated well beyond its melting point. When the ball of molten solder leaves the iron and flows into the flux on the rail, it should carry enough heat to heat the rail to a very hot temperature long enough to make a good connection."

It should. Once you touch the rail with the iron, you still need to keep it there for a second or two so the rail can get up to the same temp as the solder for the join to complete. Even if you pre-load the tip you may still have to add more solder at the joint. If you didn't get enough solder on the joint the first try, let it completely cool off before reheating and adding more solder.

Jay 

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Other builds: https://imageshack.com/my/albums 

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Posted by modelmaker51 on Thursday, July 8, 2010 1:05 AM

For the most part I agree with what  howmus said, I just want to add a few lessons I've learned along the way:

I started life as an audio technician back in late 60s /early 70s (my first paying job was assembling Heathkits, for those those that remember them). Rosin core solder was developed for the electronics industry to solder components (resisters, diode, etc.) to circuit boards where you need very little solder/flux, but for anything bigger you must use external flux; paste or liquid, it cleans the oxidation and pre-wets the surface so the solder won't bead up and helps the solder to flow, (just like ballasting track, you pre-wet the ballast with alcohol or detergent/water so the glue won't bead up).

I was also taught in electronics school never to use more heat than the job requires, a 25 w iron for circuit board work, 40w for up to 18g-16g wire (or up to code 100 rail), 100w or more for wire larger than 16g and always flux and pre-tin wires. Copper wire and brass should be tinned, surfaces that are nicklesilver (like rail) or nicklesilver plated do not need to be pre-tinned, nor do they need any other pre-treatment such as cleaning with a wire brush or alcohol (unless they are visibly dirty), the flux will do all the cleaning that is needed to make a good joint. You can be generous with the flux, but don't forget to clean all solder joins with a toothbrush and alcohol after soldering is completeted as paint won't stick well to it well.

Care & Maintenance of soldering tips. This is probably the most important part of making good solder joins. The last half inch or so of the tip should always be shiny silver, if there is any discoloration or blackening (carbon crud) it needs to be cleaned. A damp sponge will usually be enough between joins, but periodically the tip should be cleaned with tip cleaner which is available for Radio Shack and other places. It's sorta like soap for your soldering iron, you just stick the tip in it and let the "soap" melt, give the iron/tip a few twists and then wipe the tip off with the damp sponge. Add some solder to the tip and dip in the cleaner again and rewipe with the sponge and you should have a like "new" tinned tip ready to go. If you tip gets black a lot, it's time to replace it. I generally like copper tips over iron plated tips because they transfer heat better and I like to shape them to a dullish pointed tip, but they do need to be cleaned more often.

One last tip: After pre-tinning a feeder wire, I put a little "L" bend in it at the end and about a half inch down I bend it in a bit of a zig zag shape, then insert it in the hole and lay the "L" against the rail. The zig zag bend creates enough friction in the hole to keep the wire from falling through, eliminating the need for that "third hand".

Jay 

C-415 Build: https://imageshack.com/a/tShC/1 

Other builds: https://imageshack.com/my/albums 

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Posted by nscsxcrrailfan on Wednesday, July 7, 2010 10:54 PM
howmus, o.k., so you mostly use this technique as a secondary option when it the normal technique of heating the object poses a risk of melting surrounding parts such as the ties or the plastic parts on a tortoise switch machine. However, you use the regular method on devices where there is no risk of melting anything nearby. That sounds reasonable as I simply cannot make a good solder joint on track without melting the ties using the regular method of heating the rail and allowing it to melt the solder on its own. The picture you posted of your solder connection looks very close to the connections I make. I don't think that mine are as flowed out as your photo but they're very close. I definitely don't end up with any balls of solder that are easy to pry off. I used to end up with balled up solder when I first got back into the hobby in 2004. Also, I mentioned earlier that the solder I used to use was acid base. It turns out that it was rosin core solder that was very large in diameter and was very old. However, the flux I had been using up until a few weeks ago had zinc chloride in it, which I think is acid based. I'm using rosin flux now. When I think about it, I don't understand why the hot solder hitting the rail and flux would not create a good joint due to the fact that the solder has sat on the iron for several seconds and is already heated well beyond its melting point. When the ball of molten solder leaves the iron and flows into the flux on the rail, it should carry enough heat to heat the rail to a very hot temperature long enough to make a good connection. I could see how this wouldn't work with large wire such as 14 or 12awg due to the fact that a small drop of hot solder would not have enough heat on its own to heat the entire section of wire to a hot enough temperature to make a good solid connection. Of course with wire connections, one is not really concerned that much with melting anything; the insulation can simply be taped or patched using liquid electrical tape.
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Posted by howmus on Wednesday, July 7, 2010 10:38 PM

nscsxcrrailfan
to the person that was talking to me last night about the method I use with the Weller Station who had videos demonstrating this method, do you use this same method on heavy wire or do you completely heat the wire and allow its heat to melt the solder? I remember you stated that you use this same method on small audio wires. For the most part, can you create good solder connections in every situation without heating the metal by relying on flux and hot solder already melted on the iron's tip to rapidly heat the metal? I know I might be running this in the ground, but other than model railroading, I have virtually no experience with soldering on smaller or larger scales, such as electronics or piping, etc....

 

Think that was me......  You could use the same method with 14awg wire, but.....  You would certainly get much better results using an 80 or 100 watt iron.  I used to work for a telephone company as a summer hire.  I spent a whole summer back in the 1960s soldering telephone line connections inan x-y office in Victor, NY.  For that we used very large, very hot irons to do the job even with 24 or smaller wire.  The wire was wrapped around a flat connector, then the iron was placed on one side, and the solder was touched to the other side.  Again the joint was always good and done very quickly.  But...  There was nothing to melt so a lot of heat meant very quick and good work.   Personally I would not use a solder connection on very large wire in the first place.  If you must, that is the time to bring out the heavy artillery.

The technique I was talking about (which I see you found works well...) I use for small electrical connections like soldering on Tortoise Machines (where too much heat can damage the machine), toggle switches (where the same is true), Spade lug connections to small wire (where it just is the easiest way), and for rail connections with drop feeders for power (without melting plastic ties, etc...).

The key to all of this is as a couple of have said,  Find a way that works well for you and Practice, practice, practice.  If you had to tug hard to get the joint to separate, you had a good joint IMHO.  It is a solder, not a weld.

73

Ray Seneca Lake, Ontario, and Western R.R. (S.L.O.&W.) in HO

We'll get there sooner or later! 

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Posted by nscsxcrrailfan on Wednesday, July 7, 2010 10:14 PM
O.k., I spent all day working on the layout, mostly soldering. I tried a variety of techniques. This post is somewhat lengthy due to all the steps involved in the two methods I tried today. First, I got out my old soldering gun. It is 100/140 watt. At 140 watts, I waited until the gun heated up and tinned it with some solder. Then, I cleaned the tip with the sponge that came with my Weller station. I applied the tip of the gun to one side of the wire that I was going to use as a feeder and the wire instantly heated up. The solder melted without the need of any extra flux. I cleaned the spot on the side of the rail where I wanted my feeder. I then applied the tip of the gun to the place where I wanted the wire and applied solder. The rail heated up and melted the solder without melting any ties. Then, I applied a tiny amount of flux to the cooled off solder. I then placed the tinned wire right up next to the solder & flux on the side of the rail. Then, I applied the gun to the top of the rail and the tinned wire and solder/flux on the rail melted and fused together. I held the gun on long enough to see the solder on the wire and the solder/flux on the rail boil, melt, and fuse together. I did not have any ties melt. At first, I thought I had found a better way of making feeder connections (almost identical to the methods recommended by most model railroaders), however upon inspection I noticed the solder was a light white color (cold solder appearance). I waited a few seconds and reapplied heat and ended up with the same result. I tried the same technique on a rail joiner to see how the gun would handle that. I applied a small amount of flux and touched the tip of the gun to the top of the rail joiner. I then applied solder to the joiner, which melted after 1 second. The problem this time was the rail turned dark brown/black and even melted a few ties. The solder dried a white color. So, I went back to my Weller Station and used my original method. I stripped the wire and applied a small amount of flux to the bare part of the wire. I made sure the iron's tip was tinned and cleaned with the sponge. Then, I held the iron to the wire and applied solder, which melted onto the wire (the flux accelerated the melting). Then, I cleaned the area where I planned on placing the feeder. I applied some flux to that spot. With the iron already tinned, I added a small bead of solder to the tip (the iron was on the middle setting 3 approx. 25 watts). I touched the wire's tinned end to the cleaned area where the flux is and placed the iron's tip to the rail/wire. The solder bead flowed from the iron's tip onto the flux, mixing with the solder already tinned on the wire. I removed the tip and allowed it to cool. The result was a somewhat shiny connection, rather than the white looking solder I got with the gun. I tested it by pulling on the wire. This was a test connection so I yanked about 5 times on the wire and it pulled away just a little but was still secure on the rail. I then gave it a really good yank, even bracing my hand on the track while I pulled and it finally came off. Now, with my soldering of wires without track, I found the gun to do a little better job than the iron. I had three 22awg wires twisted together, and with the iron on 3, I was able to get solder to melt within a few seconds. However, I couldn't get the solder to melt on a connection between 22awg wire and 14awg. I turned the iron up to 5 (max. at 40 watts) and the solder melted within a few seconds without the aid of flux or touching the solder to the iron. I tried the gun on the wires, and it melted the solder within a few seconds on both 22awg connections and 14awg. So, from my experience, the Weller Station seems to do a better job overall. Even though I cannot heat the rail using the Weller iron without the risk of melting ties, it still seems to create a very good connection using flux (without flux I think it would be impossible due to the boiling away of the flux on the soldering iron's tip). QUESTIONS: In General, if your solder connection is somewhat shiny and silver and holds without breaking by giving it a few gentle tugs, is it a good connection or not? AND ... to the person that was talking to me last night about the method I use with the Weller Station who had videos demonstrating this method, do you use this same method on heavy wire or do you completely heat the wire and allow its heat to melt the solder? I remember you stated that you use this same method on small audio wires. For the most part, can you create good solder connections in every situation without heating the metal by relying on flux and hot solder already melted on the iron's tip to rapidly heat the metal? I know I might be running this in the ground, but other than model railroading, I have virtually no experience with soldering on smaller or larger scales, such as electronics or piping, etc....
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Posted by germanium on Wednesday, July 7, 2010 2:44 PM

I use a temperature controlled station with a heat indicator. When the control shows that the iron has reached the correct temperature, I always allow five minutes before  tinning the iron. This ensures that the temperature is correct.

Dennis 

 

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Posted by 1948PRR on Wednesday, July 7, 2010 2:03 PM

The OP is absolutely correct.

You DO need three hands.

This is just a fact.

 

I had mine grafted on in the 1980's, but for a different reason.

It has served me well in soldering, though.

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Posted by dstarr on Wednesday, July 7, 2010 1:33 PM

 The purpose of flux is to remove corrosion on the surface and let the molten solder touch clean metal. As the soldering iron heats the work, the hot metal starts grabbing oxygen molecules out of the air and forming a coat of unsolderable oxide.  The flux counter acts this and keeps the surfaces clean, long enough for the solder to adhere to the metal. 

  They make acid flux and acid core solder.  These are for plumbing work only.  Never use acid flux for electrical work.  The acid stays active, and is strong enough to corrode small wires thru given a few years. Always use rosin flux.  The rosin flux is only active when it is hot and melted.  Cool and solid, it doesn't corrode stuff, or at least the corrosion rate is a whole bunch less than acid flux.  

  The flux lets the solder wet the work.  If the solder beads up into little ball shapes,  the work is dirty or oxidized and the solder isn't making contact with bare metal.  

  Always use 60/40 tin lead solder.  60/40 has the lowest melting point, about 190C, or twice boiling water.  Hot enough to melt plastic.

  Avoid 50-50 solder, that's only for plumbing.  The recent anti lead phobia has resulted in a lot of "lead free" solders.  I don't trust them.  Tin lead solder has been around for thousands of years and it bonds well and stay bonded.   

  The tip of the iron or gun MUST be tinned.  That means covered with a silvery coat of melted solder.   Keep a damp sponge on the bench to wipe the hot tip on and keep it bright.  If the tinning wears off or burns off you must renew it.  Or replace the tip.

  When a well tinned tip is pressed to the work, the melted solder flows to the work and makes a solid connection that will flow huge amounts of heat.  If the tip looses its tinning, it takes forever to get the work hot enough.

 

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Posted by duckdogger on Wednesday, July 7, 2010 11:47 AM

 An alternative to soldering the feeder, or even just the joiner to 2 sections of track, is to use some of the Fast-Tracks  copper clad  PC board crossties. They are pre-gapped so they don't create a short.

I remove one or two of the flextrack (or turnout ties) at a rail joint, insert a PC board tie aligning the inside of each rail with the gap in the cladding.  I then apply my solder to the tie at the joiner.  You can also include your feeder wire, or solder it separately to the underside to the tie before installing.

You avoid melting ties (although I still apply a heat sink) and avoid creating a high spot where the joiner would have rested on the plastic ties.  Lastly, you maintain the track's gauge as the gaps in the PC board ties match the NMRA clearance dimensional standards.

Trains. Cooking. Cycling. So many choices but so little time.
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Posted by nscsxcrrailfan on Wednesday, July 7, 2010 10:15 AM
I've made a lot of progress when it comes to soldering. When I started out about 5 years ago, I made the worst looking solder connections you could imagine. I was in HO Scale then, and I thought I had to have big globs of solder using heavy duty wire. The solder I used was some old acid base stuff (really big sized), and I didn't even use flux. Flash forward to today, and now I'm using a Weller station with rosin 60/40 solder. Just recently, I started using rosin flux. I had been using an old flux that we had bought about 20 years ago. It turns out I think it was acid base although I'm not sure. I might have some rail connections turn white in a few years but by then I'll be on to another layout. The layout I'm working on now is Layout 3, and even with the mistakes I've made on it, it is still much better than the previous two layouts I have built.
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Posted by Forty Niner on Wednesday, July 7, 2010 7:53 AM

For better than 40 years now I have never soldered wire directly to the rail, I "always" solder it to the bottom of the rail joiner instead. I can take a group of rail joiners to the work bench, solder them up and have enough to last for several days of track laying at one time.

I also use a "small" torch or my soldering "machine", something I learned as a result of soldering on brass engines.

And, I only use "Tix" solder and flux, a small bit of Tix flux, then the heat and it flows beautifully and it's a very strong bond.

The soldering gun and the "Home Depot" solders I reserve for using on the wiring such as the feeders or most any under the table soldering.

The main thing is I solder it to the rail joiners, haven't melted a tie since I started doing it this way.

Mark

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Posted by cordon on Wednesday, July 7, 2010 2:44 AM

Smile

Although someone briefly mentioned it above, I didn't see any emphasis on tinning the rail.  It really makes the rest of the job go much easier.  Here are the steps I go through:

     Apply a small amount of flux to a small surface of the side of the rail.

     Apply flux to the tip of the iron.

     Apply a small amount of solder to the tip of the iron and wipe the tip on the damp sponge.

     Touch the solder and the tip of the iron to the side of the rail where the flux is.  Remove both immediately after the solder melts, which should happen in about a second.  The result should be a smooth and shiny layer of solder on the side of the rail.

     Tin the end of the wire and place/clamp it so that it leans against the side of the rail where you have tinned the rail.

     Apply a small amount of flux to the assembled joint.

     Apply flux to the tip of the iron.

     Apply a small amount of solder to the tip of the iron and wipe the tip on the damp sponge.

     Touch the tip of the iron to the joint just long enough for solder to melt and flow.  It should happen in about a second.  The result should be a shiny layer of solder smoothly blended over the wire and the rail.

Another possible problem is the type of tip on your soldering iron.  I participated in a couple of threads three years ago in this forum on the relative performance of iron tips and copper tips.  You can find these by doing a search on "solder tip question" in Model Railroader Forums.

Smile   Smile

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Posted by Allegheny2-6-6-6 on Wednesday, July 7, 2010 12:15 AM

 Read Jim Hediger's article in this moths MR about soldering track feeders etc. I think you'll find it very informative. The most important things you can do to become a good solder is practice practice practice

Make sure your iron is always clean and you final solder joint is nice and shinny a dull looking joint is a sure sign of a cold solder joint. In my opinion there is no such thing as overkill when it comes to soldering.as far as having a higher wattage iron then necessary. A higher wattage iron simply menas your work surface will heat up faster and give you less change to melt ties

Just my 2 cents worth, I spent the rest on trains. If you choked a Smurf what color would he turn?
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Posted by nscsxcrrailfan on Tuesday, July 6, 2010 11:55 PM
O.k., I found a website that talks about flux and refers to situations like ours where we cannot heat the wire/rail first before applying solder. Here's what the website said "For typical through-hole component soldering, heat is applied to the components, and then solder is melted directly on those components. Part of the reason that solder is applied directly to the parts and not the iron is that if applied to the iron first, the flux would likely burn off before being able to clean the joint. Unfortunately, in surface mount soldering, the leads are too small to apply solder to them directly, so it must be applied to the soldering tip first. To ensure that active flux is available when the joint is being made, it's necessary to apply additional liquid flux directly to the joint. The extra flux also reduces the solder's surface tension which helps it wick into the small connection areas. Flux also acts as a blanket that helps to spread heat out and prevent additional oxidation from occurring before solder reaches the joint. The main trade-off with flux is its activity level. Higher activity means it will help solder cling to metals faster, and also be able to handle heavier oxidation and much more stubborn oxidation (stainless steel, aluminum). The downside to higher activity is that residues left over can be corrosive and destroy components, be conductive themselves, or provide an environment that allows conductive tentacle-like "dendrites" to grow. Because of this, use the mildest flux that does the job, and if a more active flux is needed, clean thoroughly." So, basically either method is correct. From what I understand, in model railroading (specifically track feeders & rail joints) you can use either a big soldering gun to heat the rail quickly and apply solder from a spool or you can use a lower watt iron and apply solder to its tip (not referring to tinning which is done with either method) and use extra flux on the connection. With the second method, the solder does not need melted because it already is and is at a very high temperature. Of course, applying it directly would not work because the flux would likely be gone. However, using an external supply of flux on the area fills in that missing part of the equation. So basically, the molten solder on the tip of the iron is equivalent to using a 250 watt gun, except the gun is not needed because the solder is already heated far beyond its melting point. I think I understand it. If the experts here see any errors in my understanding of this please let me know, and thank you for all the advice I have received so far.
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Posted by tinman1 on Tuesday, July 6, 2010 11:06 PM

 

I'll chime in on this. Trying to heat the wire with a dry tip means only a small area of the tip is touching the wire. With a bit of solder on it, the area being heated is much greater. I think your missing the whole temp/time thing. There is no set time, and temp has only a minimum. There are many different types of solder and they have different melting points. I think I've seen them down to 300F and goes up from there. Once the solder flows, the temp is good. Solder will look like a bead if the temp is not hot enough on one of the metals, but will look flat when it does flow. You don't need a big blob to get the job done, it's not a structural thing. I use a little flux on the parts to be soldered, and a little solder on a pencil tip iron. Normally its a 40W, but I use a 25W for smaller items. I also use plumbers putty for a heat dam. It's cheap, available everywhere, will conform to any shape, and shunts heat well.
Tom "dust is not weathering"
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Posted by nscsxcrrailfan on Tuesday, July 6, 2010 10:57 PM
Yeah, I cut the speaker wire ends off and stripped off insulation to apply a new coat of solder. Looking across the internet, it seems like there is a division between those who prefer smaller wattage irons and stations and those who prefer the big solder guns for model railroading. I have an old solder gun, but I always have trouble with it burning the tips out. There are many who strongly recommend making sure the rail is hot enough to melt the solder by itself, but I don't see how you could do that without melting the ties. It might not be that big of a deal because it does seem like Nickel Silver gets much hotter than 14awg or higher copper does.
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Posted by howmus on Tuesday, July 6, 2010 10:49 PM

nscsxcrrailfan
I had to apply some solder to some old stereo speakers a few weeks ago, and I heated the wire first and then applied solder. It seemed like it took a long time to heat up though.

 

Did you cut the wire back to make sure it isn't corroded?  That is usually what I find when I have had problems doing that...  Fixing audio equipment was how I learned the technique.  (I owned a Music Recording/DJ Business for about 15 years.)  The molten solder will aid in transferring the heat quickly into the connection.  When using stranded wire (like audio wire), I usually like to pre-tin the wire before actually making the joint.  Seems to work better.

nscsxcrrailfan
if it is o.k. to rely on flux instead of heating the wire/rail to hot temperatures?

 

Answer?  Yes.  The rail will get hot enough to make the joint.  As soon as you see the solder flow into the joint, it is done.  That will happen usually in a second or less.  You want a quick transfer of the heat.

Here is a photo of the finished result:

Also another short video from the clinic showing other electrical soldering using the technique.  Notice where i am holding the wire....  If I touched it half an inch closer to the joint, i would have burned my fingers.  I let go when the wire got hot.......

http://s66.photobucket.com/albums/h259/slow_rr/SLOW_RR_II/?action=view&current=SolderingTech1.flv

BTW, I don't solder home wiring.... Something about the code....Whistling

Ray Seneca Lake, Ontario, and Western R.R. (S.L.O.&W.) in HO

We'll get there sooner or later! 

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Posted by nscsxcrrailfan on Tuesday, July 6, 2010 10:20 PM
I posted right at the same time that you responded to my questions. That seems to answer most of my questions, but I still want to know if in general (Audio equipment, home wiring, etc...) if it is o.k. to rely on flux instead of heating the wire/rail to hot temperatures? I had to apply some solder to some old stereo speakers a few weeks ago, and I heated the wire first and then applied solder. It seemed like it took a long time to heat up though.

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