Soldering Tips

Most HO Slot Car racers will find that from time to time they need to solder electrical connections on their race tracks. Soldered electrical connections are the most reliable type of joint you can create, and will assure safe and uninterrupted slot car racing for many years to come.

Soldered electrical connections are easy to create if you have the proper tools. A complete kit of soldering equipment can be purchased for $30.00 to $60.00, and can be used for all types of other soldering projects around the shop and in your home.

Weller offers a variety of soldering irons and assorted tools and accessories. In the past Radio Shack was also a good source for soldering products but in recent years their shift away from electronics products for the hobbyist to cell-phones and calling plans no longer makes them a good source for electronics tools.

To purchase the soldering equipment discussed here see the Soldering Tools & Supplies section at the end of this page.

Modular Handle

Weller Soldering Handle The Weller Cool-Grip Handle is an excellent value. This handle is designed to accept a number of different thread-in heating elements.

You can do all kinds of different soldering operations by simply changing to the appropriate heating element.

Modular Heating Element

Weller Heating Element The Weller 45-Watt Heating Element is a good choice for general purpose soldering operations. A 25 and 35 watt heating element are also available, but for track wiring chores the 45-watt model is recommended.

The secret to successful soldering of track power rails requires that you use an iron hot enough to heat the steel rails quickly, so that solder will flow, but the surrounding plastic track doesn't melt.

Smaller 15-35 watt irons will take too long to heat the rail sufficiently, and the plastic track will melt while the rail is slowly being heated.

Modular Soldering Tip

Weller Soldering Tip (Chisel) For soldering track power rails you'll need a Chisel tip, not the Pencil style which tapers to a point.

A Chisel tip has more contact area and will heat the rail much more quickly than a pencil-pointed tip can.

Combination Heater & Tip

Weller Heater with Integral Chisel Tip Weller also makes a 45 Watt Thread-In Heater with an integral Chisel tip that's a full 1/4" in width.

This is the bad boy I use, and strongly recommend. It makes soldering power taps and power rails a breeze.

Soldering Stand & Tip Cleaner

Weller Soldering Stand & Tip Cleaner Weller has a Soldering Iron Holder and Tip Cleaner as well. This item is highly recommended. Not only will it provide a safe place to set your hot soldering iron, but more importantly, it also includes a tip cleaning sponge.

The tip cleaning sponge should be moistened each time you plug your soldering iron in. One of the most common causes of weak solder joints is a dirty soldering iron tip. The tip cleaning sponge eliminates this problem. Get in the habit of running your soldering iron tip over the cleaning sponge each time you place the iron back on the stand as you work.

Clean the tip after you've used it. The water trapped in the cleaning sponge cools the tip, so if you were to run it over the sponge just before soldering a joint it will take longer for your iron to heat up again. Cleaning the tip after every joint you solder will become routine after a while and guarantee solid connections.

Budget Soldering Kit

Weller 40 Watt Budget Soldering Iron Kit Weller has a soldering iron kit for the budget minded hobbyist that includes a 40 Watt heater/handle, 1/4" Chisel tip and small stand. The tip is replaceable, but the heater itself is not.

If you don't want to go all out and purchase Weller's modular soldering system then this kit makes a nice low-cost alternative.

An 80 Watt unit is also available. It's intended use is for scratch-building brass slot car chassis only and should not be used for electrical track work.

Soldering Tools

6-Piece Soldering Tool Kit A set of soldering tools makes most soldering tacks much easier. A good set will include several pointed tools for holding wires, along with clamps and heat sinks.

Solder & Flux

Solder and flux come in two distinct varieties; rosin core and acid core. Use only rosin core soldering products for electrical connections. The labeling on the package will clearly state if the soldering product is designed for electrical work. Acid based soldering products are normally used for plumbing, rain gutter repairs and stained glass work. These acid core types of solder must not be used for electrical work.

Rosin core solder used for electrical work is actually a lead/tin alloy with a hollow core containing a rosin cleaning material. As you heat the solder and apply it the rosin melts and cleans the work being soldered. Rosin also allows the solder to flow more freely over the heated area.

Soldering flux is a liquid or paste material that can be applied prior to heating a joint. It has a cleaning agent that clears the metal of any impurities and allows heated solder to flow more easily. Soldering flux is normally used when the items being soldered are dirty or large in size.

Tinning The Tip

The tip of your soldering iron needs to be tinned before it's used. Tinning is the process of coating the tip itself with solder. Heat your soldering iron up for the first time and then apply solder directly to the tip. The solder should melt and flow easily over the tip. Wipe any excess solder off by running it over the moistened tip cleaning sponge. Repeat this process several times until the tip is a shiny silver color.

Repeat the tinning process from time to time when you see that the tip is no longer a shiny silver color when heated. With use your soldering iron's tip may become dirty. To clean the tip let the iron cool to room temperature and remove any dirty or burnt plastic wire insulation that may have collected on it with a fine grade of emory cloth. Remember to tin the tip again after you've cleaned it.

Soldering Wires

Soldering all of your slot car track's wire connections will guarantee good electrical connections. A good electrical connection starts with clean materials and a good mechanical connection first though. If you are connecting a wire to a terminal strip or another piece of wire make a good strong mechanical connection first by crimping the wire with a pair of needle-nosed pliers.

Try to avoid touching the bare metal parts you will be soldering. The oil from your fingers will prevent the solder from flowing properly. If the parts to be soldered are dirty apply a small dab of soldering flux to them before soldering. Flux will clean the part and allow the solder to flow more easily.

With a good mechanical connection made you are now ready to solder the joint. The process of soldering involves heating the material to be soldered with your soldering iron. Your soldering iron is designed to heat the material being soldered, not the solder itself. Hold your soldering iron firmly against the item to be soldered and keep it there for about 15 to 30 seconds before applying solder.

After you've held the soldering iron on the piece to be soldered apply a small amount of solder to the work itself. Do not apply solder directly to the soldering iron tip and allow it to melt and flow onto the work though. You want the heated wire and terminal itself to be hot enough to melt the solder and allow it to flow over the entire connection.

Good soldering technique involves heating the work to be soldered sufficiently to melt the solder and allow it to flow easily over the material being soldered.

Heating solder on the tip of the iron and hoping it flows onto the item being soldered is not how soldering is done, and will all but guarantee cold solder joints that break and do not conduct electricity.

If you're touching the solder itself to the tip of your soldering iron to get it to melt then you are either not waiting long enough for the iron to heat your work, or the soldering iron heating element is too small for the work being done.

Once the solder has flowed evenly over the parts being soldered gently remove your iron from the work and let the solder cool naturally. Do not blow on a warm solder joint as this will fracture it. Let it cool naturally. A good solder joint will appear shiny and silver in color, but if it's a dull hazy silver color it either means the material was not heated sufficiently before the solder was applied, or the joint is contaminated with dirt or oil.

A dull hazy solder joint is often referred to as a cold soldered joint. Cold solder joints do not conduct electricity reliably, so if you suspect cold soldered joints re-heat them and apply new solder again.

Soldering Power Rails

Your slot car track's power rails can also be soldered. Soldered power rails will allow electrical current to flow more evenly around the entire racing circuit, and also provide for a smoother running race track. The power rail connections at each track section joint will need to be soldered.

You should start by thoroughly cleaning the entire track surface before you begin. Formula 409 Heavy-Duty Cleaner and Degreaser sprayed on a clean lint-free rag can be used to wipe down the entire track. Follow this up by wiping the track dry with a second clean lint-free rag.

With a clean dry track, apply a small dab of soldering flux on each of the power rails connections on a single section of track. Soldering flux is a must here. The metal power rails are made of a type of steel that needs to be very clean in order to allow solder to adhere to it. Soldering flux also contains a cleaning component that will properly prepare the metal for soldering.

Place your soldering iron's tip on a rail joint so that both sides of the joint are in contact with the heated tip. Let the metal rails heat up sufficiently to melt the flux and then apply a small amount of solder. Remove your soldering iron and let the joint cool naturally. Repeat this process for each joint in a single section of track.

If you're unsure of your soldering abilities practice the steps outlined above on scrap track sections until you feel comfortable working on your actual race track.

Soldering each and every power rail connection on your race track can take quite a while to complete, but the improved electrical current flow around the racing circuit will be obvious the first time you race on it. Take your time, and complete the work in sections. If you run cars on the track before completing the entire layout then re-clean the track before you continue soldering. The oil from your cars will get on the power rails and prevent good solid solder joints.

Silver-Plated Pickup Shoes

You can also improve the performance of your HO slot cars by tinning the pickup shoes with silver solder. Silver solder is available at most hardware stores and hobby shops. Silver solder however has a higher melting point than does normal lead/tin solder, so make sure you heat the pickup shoes sufficiently before tinning them.

Start by removing the pickup shoes from the chassis. Keep an eye on those small pickup shoe springs directly beneath the shoes and set them aside where they won't roll of your workbench and onto the floor.

With the pickup shoes removed, lightly sand them with fine grade emory cloth until they shine. Then place them in a small hobby wise or clamp of some type to hold them securely. Heat the shoes with your soldering iron and then apply silver solder to the contact portion of the pickup shoe. Let the silver solder flow evenly over the contact area and then remove your soldering iron. Repeat this process for the other shoe as well.

Shunted Pickup Shoes

Another way to improve your slot car's performance is to solder short flexible shunt wires directly to the rear of the pickup shoes and also to the motor's brush connectors. HO slot car pickup shoes normally conduct electricity to the motor via a mechanical hinge connection at the rear of the pickup shoe itself.

To improve the flow of current you can add pickup shoe shunt wires. Take a short length of 16 or 18 gauge stranded wire and remove about three inches of the plastic insulation to expose the bare stranded wire.

Cut the exposed wire off and then separate the individual strands. You should wind up with several lengths of very fine copper wire that are ideal for shunt wiring.

With the pickup shoes removed from the chassis, solder a single shunt wire at right angles to the bottom of the shoe. Repeat this process for the other pickup shoe as well, but solder the second shoe's shunt wire in the opposite direction. You should end up with a pair of pickup shoes, that when re-installed each have a single fine copper wire exiting towards the outside of the chassis.

Re-install the pickup shoes and springs on the chassis and then locate a point on the chassis or motor that is in direct contact with the motor's commutator brushes. Trim the shunt wires to length and carefully solder the other end of each shunt wire to this corresponding point.

Electrical current can now flow directly to the motor brushes via these shunt wires regardless of the condition of the pickup shoe retainer hinge.

Practice Soldering

If you're new to soldering, take the extra time and practice soldering scrap wires before attempting to solder your track's wiring or slot car parts. Soldering is not difficult, but if you're just starting out, practicing your newly acquired skills on unwanted items will assure that you don't damage your track or cars. Once you feel comfortable handling a soldering iron you can move on to the examples described above.

If you're planning on soldering your track's power rails practice first on some of those unused 6" or 9" radius turns, or 3" straights. Once you've perfected your technique you can move on to actually soldering your track.

Soldering Tools & Supplies

I stock and sell the correct tools and supplies needed for making power tap tracks and for soldering the rails on your slot car track for a smooth continuous flow of electrical current.

The tools listed below are the tools and supplies I use daily when making Custom Power Tracks and the Commercial Tracks I design and build for my customers.

View Weller Soldering Iron Handle in Pop-Up Window Weller Soldering Iron Handle $27.99
View Weller 45 Watt Heating Element in Pop-Up Window Weller 45 Watt Heating Element $36.99
View Weller 1/4" Thread-On Chisel Tip in Pop-Up Window Weller 1/4" Thread-On Chisel Tip $8.99
View Weller 1/4" Heavy Duty Chisel Tip in Pop-Up Window Weller 1/4" Heavy Duty Chisel Tip $10.49
View Weller 45 Watt Heater w/ Tip in Pop-Up Window Weller 45 Watt Heater w/ Tip $55.99
View Weller Soldering Stand & Cleaner in Pop-Up Window Weller Soldering Stand & Cleaner $42.99

View Weller 40 Watt Budget Soldering Kit in Pop-Up Window Weller 40 Watt Budget Soldering Kit $29.99
View Weller Budget 1/4" Replacement Tip in Pop-Up Window Weller Budget 1/4" Replacement Tip $13.99

I also stock the Weller Budget Soldering Iron Kit that includes a 40 Watt Heater in the handle, a 1/4" Chisel Tip and Stand.

View Weller 80 Watt Budget Soldering Kit in Pop-Up Window Weller 80 Watt Budget Soldering Kit $46.99
View Weller Budget 3/8" Replacement Tip in Pop-Up Window Weller Budget 3/8" Replacement Tip $14.99

This 80 Watt soldering iron is designed for scratch-building brass slot car chassis only and should not be used for electrical track work.

  Soldering Flux Paste (2 Oz. Tub) $12.99 Temporarily Out of Stock
View Solder 60/40 .031" - 1 Pound Spool in Pop-Up Window Solder 60/40 .031" - 1 Pound Spool $35.99
View Six Piece Soldering Tool Kit in Pop-Up Window Six Piece Soldering Tool Kit $5.99


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Page last updated on 27-Jan-2020