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Must-Know Soldering Tips

Must-Know Soldering Tips

There is always that occasional opportunity to do some soldering. When you need to add some connectors to a battery pack, or to make a set of wiring adapters for your battery charger, using heat and molten metal to join wires together is one of the oldest do-it-yourself tasks for RC hobbyists. The task is usually very simple: just add heat and solder, and you’re done! But for the haven’t-done-it-yet newcomers in the crowd, there’s a little more to it than that.  Here are a few helpful hints to get you started!


Must-Know Soldering Tips
Must-Know Soldering Tips
Must-Know Soldering Tips
Must-Know Soldering Tips

For basic wire, motor terminal and speed control soldering, you’ll need:

  • 40/60 rosin-core solder
  •  25 to 40W soldering gun or pen
  •  Moist sponge to clean the soldering tip
  •  Basic tools (clothespins and alligator clips) to hold parts, pliers, etc.
  •  Tube of soldering flux for soldering and tinning metal parts
  •  Heat-shrink tubing to insulate wire solder joints


Must-Know Soldering Tips

1 Start by stripping the plastic insulation off the ends of the wires (usually, 3/16- to 1/2-inch is plenty).

Must-Know Soldering Tips

2 Set up the wires in your holding jig. Tin the ends of the wires by lightly applying a small amount of solder to the exposed wire and allow it to flow into its strands. Apply the heat to one side of the wire and touch the other side with the solder. When the wire is hot enough, the solder will flow into the wire braiding.


A piece of pine, two wooden clothespins and some ZAP is all that's needed to make a holding jig for soldering.
A piece of pine, two wooden clothespins and some ZAP is all that’s needed to make a holding jig for soldering.
snap off the clothespins
You can snap off the clothespins easily and reglue for different jobs. The cost is nothing!
Commercial soldering jigs
Commercial soldering jigs like this one from Tingler Innovations (solderbuddy.com) are also a good investment.

The first thing you’ll learn is that to solder anything together, you’ll need an extra set of hands, especially when trying to solder two wires together. With solder in one hand and the soldering pen in the other, how do you prevent the wires from moving around? With a handy-dandy “third-hand” holding jig, of course! You can easily build such a holding aid with a wood base and a couple of wooden clothespins glued to it. A holding jig or fixture will pay off the very first time you use it-take my word for it! You can glue the clothespins in the exact placement you need for a specific job and then you can snap them off and reposition them whenever the need arises. I don’t think that you can really do a good soldering job without one!

Must-Know Soldering Tips

3 Slip some heat-shrink tubing over the wires and push them away from the solder joint area. Position the ends of the wires together, then reheat the wire. Watch the solder tinning. When it liquefies and flows together, add just a little more solder to fully fill in the joint.

Must-Know Soldering Tips

4 Remove the solder and the heat and allow the joint to cool off. Don’t move or budge the wires. If they move while the solder is still hot and fluid, you’ll create a weak “cold joint” that can break easily from vibration while your plane is in the air.



Must-Know Soldering Tips
  • ¶ When in doubt, use a bigger soldering pen. More heat is always better than not enough. If your solder takes more than two or three seconds to start flowing, you don’t have enough heat.
  • ¶ For most everyday soldering, standard rosin-core solder works great. For very fine-wire gauges (like servo leads), use thin solid-core solder and apply a dab of solder flux paste to the wires.
  • ¶ Keep your soldering tip clean. Use a damp sponge and wipe the tip between each use.
  • ¶ Use only resin-core solder or flux paste with braided wire. Liquid soldering flux can wick into the plastic insulation and cause your wires to corrode over time.
Must-Know Soldering Tips

5 Once the solder joint has cooled, slide the heat-shrink tubing over the joint and shrink it into place. I like to do this with a hot air gun used for shrinking plastic covering. It’s quick and easy and the heat gun won’t melt the wires or the solder.

Of course, it takes practice to improve your skills so cut up some wire and solder the pieces back together. You’ll be a soldering pro in no time at all!

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Updated: September 28, 2016 — 4:36 PM


Add a Comment
  1. Hi Debra…. I am enjoying a free edition of your digital mag. Great job overall, but the soldering article may cause problems. Under most conditions joining wire needs more than just “laying them side-by-side and soldering — especially in a vibration environment. If you are interested, I would love to send you a pdf copy of one of our club’s newsletters which I devoted entirely to soldering, but don’t know your email address to do so.

    1. Hey there
      Is this newsletter available to folks outside your club?

    2. Hi Ron, would you please send me a copy of your club’s newsletters devoted entirely to soldering?

    3. Hi Ron,
      would you please send me a copy of your club’s newsletters devoted entirely to soldering?



    4. Ditto, thank you!

    5. Holy cow! You have an entire newsletter all about soldering!?!??! PLEASE sign me up!! Let me know how to get a copy of that. I’ve been soldering for a long time but I never imagined it was so complex that it required a whole newsletter! I’m SO looking forward to seeing what I;ve been missing…

  2. Most good soldering practices encourage a good mechanical connection first. One should wrap the wires around each other first, starting in the center of each lead!

  3. You are absolutely right. Good soldering requires a good mechanical connection before the soldering.

  4. Another tip, which any plumber would know is to always use flux. Flux allows the solder to flow more easily. When soldering wires, simply dip the bare ends into the flux before applying the heat. Then watch how easily the solder will flow.

  5. I would like a copy of the club newsletter on soldering. Thanks

  6. To make a very slim clean joint you can gently push each bunch into each other (end to end0 so individual wire fibres? slide past each other into the bunch then solder as usual.

    3 important points mostly overlooked in how to solder articles.
    1. clean everything! not just the iron. wipe solder wire through a tissue to remove the dull patina just prior to the solder. wipe the wire or copper board with a cloth with a slight damp of weak solvent such as meths.
    2. Tin each component wire, board, wire or tab . heat and apply a thin (just wet look) amount of solder to each surface.when marrying the 1 objects.
    3. touch solder between iron and joint to form a heat bridge and let the tinned surfaces and heat bridge meld for a shiny joint.
    This should only be enough solder to soak the components but enable individual wires to show under solder (not a blob).
    Grey or sugary joints are dry joints and should be cleaned and redone.

  7. What brand of soldering iron would you recommend? Great article. Thanks for posting. I would also like a copy of that Club’s Newsletter on Soldering Tips.

  8. RE: solders and fluxes.

    For various reasons, it is good practice to use 60/40 solder, rather than 40/60 for electronic work.

    Fluxes contain various chemicals – from mild organic compounds to powerful acids – most of which can be corrosive. On RC electronics,use only solders and fluxes made for electronics use. Unless the label says otherwise, neutralize any flux residue with an isopropyl alcohol-soaked cotton swab.

    Today, many electronics technicians and hobbyists are using soldering-flux “pens.” Flux application with a pen reduces over-use of flux. The Kester 951 Soldering Flux Pen is advertised as “no-clean.”

    Amazon.com sells flux pens.

    Steve Hollis

  9. this has really made my day I suffer from the shakes and have an terrible time soldering two wires together now with the idea of the handy jig with the clothes pegs I am saved. I would like to ask if anybody can help me I want to build BUD NOSENS P51D mustang 103 inch in aluminium. I have the plans but need the exact sizes of the wing and tailplane ribs and the body formers if anybody can help it would be highly appreciated

  10. Hello Ron,
    Please send me a copy of soldering techniques

  11. I also would like a copy of the newsletter on soldering techniques, but prefer not to post my email address to the world. Perhaps Ron / his club could set up a place where a copy could be obtained?

    And “flyoz” is correct that cleaning the solder helps too. I do quite a bit of solder work so I end up buying a 1 lb roll about every 12-15 months (on Amazon, Kester “44” rosin core, 63/37, .031″ diameter). I cut a small notch in the box it is sold in, and slip some fine steel wool over the end of the solder, then stuff the wool in the box behind the slot. Now when I pull solder from the roll, it is dragged through the steel wool and wiped clean just before using.

  12. I was lucky enough to attend a week long NASA Quality Standards soldering school while in the Air Force. I shudder looking at some solder joints I see in some models these days. Having the good mechanical connection was an absolute must in the soldering school, but, there are obviously times when that can’t be done in this hobby. Like when wires are inserted into a 4mm connector and simply soldered in. That is when knowing how to tell if the joint ‘looks’ right really helps. Practice makes perfect.

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