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Tools You Need for Model Train Soldering
Many model train beginners may feel daunted by the process of soldering. Working with high heat and small objects is understandably intimidating, but with care and practice, it is safe and simple. Soldering both strengthens metal joints and enhances electrical conductivity.
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- Most modeling projects can be accomplished using simple and inexpensive tools and materials. A small 100-watt soldering iron or gun is adequate for most track and wiring projects. A variable-watt gun with higher outputs is a good investment especially if you work in larger scales or use a larger wire. Simple irons and guns can usually be found for as low as $10.
- Resistance soldering tools are best for assembling etched metal kits or working with extremely small parts on the workbench. These tools can be found through electronics and hobby tool retailers.
- A rosin-core solder and flux paste are the other main ingredients. Flux helps the solder flow much more quickly and smoothly and is key to getting smooth joints with a minimum of solder.
- Add a sanding block to clean parts before and after soldering, a couple of heat-sinks for working in tight areas around other solder joints you don't want to melt, and you have everything you need.
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Steps for Soldering
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- Clean both pieces prior to soldering. Paint, dirt, and oxidation will prevent good bonds. Strip wire insulation off only as much as necessary for the joint.
- Apply a light amount of flux to both pieces. Use a small brush, toothpick, or the end of the solder itself. Too much flux will leave a residue when finished.
- You will need to "tin" the wire or parts when working in areas where prolonged heat is problematic. Tinning puts a small coat of solder around the wire. To tin, coat the wire in flux lightly. Apply heat. Apply solder to the wire, lightly coating it.
- Use the gun or iron to apply heat, not solder. Applying a small drop of solder to the end of the iron or gun will help conduct heat. Most of the solder should be applied directly to the wire or joint.
- Hold the heat source on the joint and apply the solder on the opposite side. The heat will draw the solder through the gap and create a solid bond with minimum material.
- Clean the finished joint with a light swipe of a sanding block or a similar tool to remove any excess flux. Cleaning while the joint is still warm yields better results.
- Finished solder joints should look smooth and consistent. A light tug on parts should not be enough to break them apart.
03 of 04
The size of the rail can have an impact on soldering requirements. Large scale modelers may find a small torch necessary to generate adequate heat. In small scales, soldering the rail without melting plastic ties is the hardest challenge.
Soldering rail joints improve electrical flow and also helps maintain alignment in curves, especially with flex track.
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- Clean the rail and apply flux, as described above.
- When soldering two pieces of rail, apply the heat to one side of the rail at the joint, solder on the other.
- When soldering wire to rail, apply the heat to the wire and solder at the joint. Tinning the wire will speed the process.
- Work quickly and remove the heat source as soon as the joint is complete. It is possible to solder rail without melting the attached plastic ties. Ties can also be removed and reinstalled.
- Clean the joint with very fine sandpaper or track cleaning pad.
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As with rail, the size of the wire can impact the time and heat necessary for a good bond. A 100- to 140-watt iron should be sufficient for most model railroad applications.
- Remove only enough insulation from the wire for the joint. Be careful not to nick the wire. If you will use shrink tubing to protect the finished joint, insert it over one of the wires before soldering.
- Clean and flux wire.
- Tin stranded wire. Solid wire can be tinned as well, especially when soldering in awkward locations or when heat transfer must be accelerated like when soldering to track.
- Solid wire works best for wire leads attached to the rail. These leads can be soldered to the side, or hidden under the base of the rail. The other end of the lead is attached to a wiring bus.
- Twist wires together to provide a good mechanical bond for hands-free work.
- Finish wire connections by wrapping in heat-shrink or electrical tape.
Solder every connection as you build to prevent problems later on. A little extra time up front can save hours of troubleshooting down the road.