Seeking Soldering Masters

[Noah Lane]

I'm preparing to start my solder mission of 194 feeders to each of the 81 pieces of my Unitrack layout (yep, I counted).  I am seeking experienced soldering techniques.

- What solder brand/guage do you prefer?
- What is your preference in iron tip?
- How necessary is non-acid flux? It seems hard to find -even pretty uncommon online.
- Unitrack Users: Do you find it necessary to Dremel to widen the small rectangle gap area beneath the track that you plan to solder?
- Unitrack Users: I find it difficult to touch the iron tip to the solder and track at the same time -because the target spot on the bottom of the track is so small. In my brief practice sessions, I've applied the solder to the end of the feeder, then pressed that end to the bottom of the rail and touched my iron to adhere the feeder to the rail.  Does this sound like an okay method? How do you do it?
- My iron tip doesn't seem to stay clean for long, but I hear of the importance of keeping a clean tip.  What do you do to maintain a clean iron tip? How often do you replace it?

I'm not entirely new to soldering and have been practicing on some of my spare unitrack pieces.  I just started using the Radioshack flux (can't tell if it's non-acid), with a Weller 30 watt iron, smaller needle tip, and 22g rosin core solder.  I have read many threads, articles and heated debates on soldering techniques, but I'm really looking for some of these specifics as I begin this endeavor.

Cheers
Noah

Disclaimer: I'm new to this forum, and also new to semi-serious model railroading (I modeled as a kid, very recently got back into it). And I do use the search feature before posting new threads.

[muktown128]

Noah,

I'm not a master, but in a similar situation as you and getting ready to solder a lot of feeders to my track.  I have had similar issues with keeping the tip clean and will be interested in the responses.

Scott

[DKS]

Noah, some of your questions will inspire considerable debate, as some folks are passionate about the way they work. In many cases, there's no single "right" way to work, but there are "better" ways.

Here are my personal recommendations:

I use the finest electronics-grade solder I can find, such as Kester .020 dia. rosin-core 60/40 solder (do not bother with lead-free solder--it's more trouble than it's worth, and contrary to some reports, lead-based solder won't kill you).

For general electronics work, I prefer a small chisel tip. Fine-point tips won't work well because they don't hold enough heat to transfer to the work; a small chisel tip has the capacity to heat the wire and rail to a temperature just high enough to melt solder. Any hotter and the flux will vaporize, the metal will oxidize, and you'll have a cold joint.

As for flux, if electronics soldering is done right, you really should not need any more than what's provided by the solder itself.

You say your tip doesn't stay clean very long; this suggests you aren't using good soldering technique. The tip should remain quite clean for a good amount of time and shouldn't need replacement for years. Having said that, a non-temperature-regulated iron will be difficult to use for electronics, and is not recommended. About all these irons are good for is providing an AC cord and plug for an electronics project, such as a DIY power supply.

Some soldering technique tips:

First, you need a decent soldering iron. Get yourself a temperature-controlled iron. You don't need to spend more than $100, and your soldering jobs will be significantly better as a result. I would not even bother trying to use an ordinary iron for electronics work, and this alone is one of the biggest causes for bad electronics soldering. Seriously, ditch that 30-watt Weller in the trash and get a decent iron.

As noted before, a fine pointed tip is not recommended for electronics work because it cannot transfer heat efficiently; a small chisel-tip will hold the heat required for wiring jobs. The temperature of the iron should be set to around 350 degrees Celsius, or 650 Fahrenheit.

Have a moist (not soaking wet) sponge tip cleaner on hand. This is mostly to remove rosin residue. The tip should be tinned before using, and should be brilliant silver in color. If it's dull or dark grey, it needs to be cleaned and re-tinned.

Thoroughly clean the surfaces to be soldered, especially the rail. Oxides will interfere with soldering, and often they won't be readily visible on the surface. A small wire brush is idea for cleaning rail. If the surfaces are clean, you won't need any additional flux. Tin the wire and the rail separately first; this will reduce the amount of time that heat must be applied, and thus reduce damage to the plastic roadbed. Tinning should take about one second.

Do not apply the solder to the iron tip; this will only burn away your flux, and flux is essential for electronics soldering because it prevents the metal from oxidizing. Heat accelerates oxidation, which will prevent the solder from bonding to the metal. Touch the tip to the metal, allow it to heat the metal for no more than a second, then touch the solder to the heated metal, but not the tip.

When it's time to attach the tinned wire to the tinned rail, place the two in contact, and touch the iron tip to both of them at once; apply a tiny amount of additional solder to the other side of the joint if needed. The connection should be completed in about one second.

[bill pearce]

I am uncomfortable disagreeing with DKS, but I found flux essential in my last layout. Also, I find it easier to get non acid flux than acid. I get mine from a loal electronics supply store, not RS, and haven't had any problems. I prefer, as does DKS, Kester solder and flux. I also remember from my years in radio and tv that our engineers were, well, casual about what solder and flux they used, just whatever was on the counter at the wholesale house.
Also, if you can find any tin-lead alloy solder snap it up. The newer kind with silver doesn't flow as well as the real thing.
Bill Pearce

[djconway]

While I may not bee a master I have been soldering track for over 40 years,
1- clean the track
2- flux the track (thin film of Radio Shack flux goes a looooong way)
3- clean the tip
4- tin the wire
5- place heat sinks about 1/2" on either side of wheye you want to solder
5- clean the tip (yes again)
6- while touching the iron to the top of the rail press the tinned feeder to the side of the rail ** takes practice not 3 hands;)
7- remove the iron as soon as the solder starts to flow

Be clean - be fluxed - be quick

As to the choice of irons -- I've been using the same 27watt Weller iron since about 1980 and it has worked well for me.  I have yet to try a temp controled iron, it may be easier.
One of the best things I've done is to start using flux about 10 years ago -- OMG does it make it easier.

[Scottl]

I thought one of the great virtues of Unitrack was the excellent electrical connections.  I've never used it, but do you really need a feeder on every piece?  I don't see a problem with lots of feeders, but this seems excessive. Just a thought.

[Noah Lane]

David- that was extremely informative. I saved your narrative for future reference. I said semi-serious model railroading, but I guess this is a relative term.  What I view as semi-serious others may view as Brio.  So some of your reccomendations may be a bit beyond was is necessary for me.  Although, I do like understanding the practices of the pros.

djconway- thank you for your alternate perspective. also helpful!

Scott- that was my feeling at first. but I continued to read that for error-free DCC operation, connecting feeders to every piece of Unitrack is ideal.  So I figure, do it once, do it right. Part of my reason for getting back into model railroading was that I wanted to something to tinker with. It seems to me, a large part of the fun of a layout is in the construction. So I'm in no hurry to complete it.

Thanks again everyone!  Anymore firsthand Unitrack soldering tips would also be appreciated.

[VonRyan]

With Unitrack, Having feeders for every piece of track isn't entirely necessary unless you either run mostly sound-equipped locomotives, or you live in an area where as soon as you clean the track it becomes dirty again.

For regular operations with perhaps one or two sound-equipped locos, just have feeders every so often to prevent a major drop in power.

For my non-unitrack N-Trak module, I used sectional track on the 10" centered "branch line" and soldered every joint and a feeder was soldered to every rail joiner that wasn't an insulated joiner (I use peco electrofrog turnouts) because I plan to run locos with very short wheel bases (read: three axle steam locomotives and one extra-short three axle diesel).

Rather than solder your feeders to the track itself, I'd suggest soldering them to the unitrack joiners.

-Cody F.

[mark.hinds]

I mostly agree with DKS, but would add the following.  One caveat is that I use a resistance soldering machine to do my track feeders, but I do have pencil soldering iron experience as well. 

1)   Although you still want to clean surfaces and have a properly tinned iron, per DKS, I find that using extra rosin flux gives me more leeway in cases where parts are imperfectly clean or heat transfer is not ideal.  If you use extra flux, sop up the extra with some absorbent paper while the joint is still warm. 

2)   In any case, be sure to use non-corrosive rosin paste flux for electronics work.  Although I haven’t ever tried violating this rule, I understand that acid flux can gradually damage the conductivity of the joint.  I currently use Kester SP-44 rosin soldering paste, which I think I bought on-line from an electronics supply house.  Radio Shack also sells a non-corrosive rosin soldering paste. 

3)   Tinning both surfaces and melting them together, per DKS, works well, in cases where you are concerned about collateral heat damage (melting ties, etc.).  Another way to protect against soldering damage of adjacent parts is to use clip-on heat sinks (spring-loaded tweezers of various types).  Micro-Trains coupler tweezers work well for this.   Finally, a bowl with a damp sponge (or wad of paper towel) is handy to quickly cool the joint once the solder has set. 

4)   Don’t know if this applies to Unitrack, but I currently solder my (tinned) track feeders to the bottom of the back rail (also tinned) of my flex track, thus making it invisible once scenicked. 

5)   Lots of good soldering articles on line, such as this one: http://www.elexp.com/t_solder.htm

MH

[peteski]

If you have hard time finding nonacid flux or soldering paste then you need to stop looking for it in your hardware store's plumbing section! 

Seriously, rosin flux is widely available from any electronic supplier (including Radio Shack).  Personally, for the last few years, I've been totally sold on Radio Shack Electronic soldering paste flux. It comes in a small plastic jar and it works great with anything.

I have been soldering for about 35 years (both professionally as electronic technician and as a hobby activity) and there isn't much I would add to the excellent DKS' writeup. But I often use extra flux, especially when soldering track.  While the rosin flux core does provide plenty fo flux, sometimes the flux seems to be too "mild". That is when the past flux I use (which might be slightly more active) makes the soldering easier.  I also often have to apply solder to the iron's tip  then to the soldered joint (not enough hands to be able to hold the rosin core solder to the joint), then the separately applied flux is vital.

I will reiterate that keeping the soldering iron tip clean (so it looks shiny with a thin coat of molten solder) is very important. A decent quality temperature controlled pencil soldering station can be purchased for less than a cost of a N scale locomotive and it makes a great investment which will probably last a lifetime.  Having the right tool of the job makes the task easier and the results better.

Acid flux is bed for electricrically active solder joints because the acid is conductive and it also remains active (slowly eating away at the metal).  It can be used on joints where it can be fully cleaned off or neutralized after soldering.

[DKS]

I am uncomfortable disagreeing with DKS, but I found flux essential in my last layout.

No need to be uncomfortable; as I noted, everyone has their preferences. I will use additional flux as well, but usually only when soldering feeders to existing track (i.e., laid and ballasted), as opposed to new track which will be much cleaner and easier to solder. Where I stray from most recommendations is with my choice of flux: water-based liquid acid. Using a micro-brush, I will apply a very tiny droplet to the joint just prior to tinning. The acid flux causes the tinning to take place in a split second. When the connection is done, I thoroughly clean the joint with alcohol. I've been doing this for many years and have never had a joint fail. I have, however, seen joints fail that were made using paste flux, because most pastes are grease-based and much harder to clean thoroughly.

[towl1996]

Micro mark has a resistance soldering unit on sale.
http://www.micromark.com/microlux-resistance-soldering-unit-with-single-electrode-handpiece,10952.html. I'm thinking about getting this baby myself. 

[Carolina Northern]

As the first reply said - the answers will be all over the place.
I've been soldering professionally since the 60's and use only Unitrack -  - - - so - here's what I do YMMV.
I've been using the same Weller Soldering Station and the same tip since 1983. It's travelled with me all over the country.
As you were told - a wet sponge - and keep it clean.
I've been using the same tin of Kester soldering paste since the late 60's and still have about a quarter left.
My current - since the 80's - favorite solder is Radio Shacks's silver bearing solder.
I followed Powersteamguy's suggestion to use a feeder on every section of Unitrack and I don't worry about the joiners carrying current or signals. I have a lot of it that's used with the old joiners - no problem. 
Because I have lots of scrap lengthes, I use a pair taken from CAT5 for my feeders - usually about a foot long. My bus wires right below the track are 12 gauge.
I prep my Unitrack by opening up two of the small holes under the rail with two clips with a snipper, cleaning it up with a sharp hobby knife, when necessary - it usually isn't.
This gives you a slot about 1/4 inch long. Dab a little flux on the rail through the slot. I use a toothpick.
Strip a short length of the feeder (less than 1/4 inch) and give it a 90 degree bend. Dip it in the flux and tin it.
Press the tinned wire against the rail bottom and apply your iron. You shouldn't need more solder, but if you do - just a little and get the iron off quick - as soon as the solder flows. Clean your tip.
Drill a hole under the track, drop the feeder and solder it to the bus - I use a weller 100/140 gun for this. The reason the feeders are around a foot, is I gather several and make one joint.
Nobody can tell you the "right" or "only" way, but this has worked well for me for many years.

One last note - you don;t have to do this all at once. Lay out your track and run some trains. Take up a few pieces at a time and add the jumpers when you get the urge - or better yet - get a few spare pieces and work you way around the layout replacing ones without jumpers with ones that you have prepped.
Either way - have fun.

[johnh35]

Adding to what has already been said, don't solder to the track directly, solder to the uni-joiners. You can take them apart to solder to the metal connector . Use a 45 watt iron versus a 25 watt, but only heat the connector enough to melt the solder.

[Noah Lane]

Peteski- I picked up the Radio Shack flux prior to composing this thread.  I suppose I didn't understand that Rosin core meant non-acid.  I was just looking everywhere for a package that said "non-acid" as I had read that recommendation many times.

Carolina Northern- You pretty much filled in all the details I was looking for regarding Unitrack.  Thank you very much!

It seems two of the great Unitrack debates that will never be agreed upon are:
1) Whether or not to solder each piece of track. My thoughts are, why not?  I'm in no rush to finish my layout -most of the time I'd rather be soldering that sitting in front of the TV. And hey, it doesn't hurt to have that much more practice at soldering.
2) Whether to solder to track or Unijoiners. I see the benefit in each route. As for soldering to Unijoiners, there is value in easily being able to shuffle track pieces around. But as far as conductivity goes, it seems that soldering directly to the track rails would be at least marginally better.

When it comes to good joint versus cold joint, I am told the good joint will look shiny like chrome, and cold joints will look dull.  Well, I find that some of mine look a very shiny and proper, and others are bit dull, but not matte gray.  How can I immediately tell if the joint needs to be re-soldered?