How Any One Can Solder

by Bob Herrick

In the world of Slotcar racing we have noticed that there are two kinds of racers, those who try to make race-cars from toy slot-cars  and those who build race-cars  The secret to a fast Race-car is the quality of fabrication and attention to detail. We have seen many racers who would be more successful and less frustrated if they paid more attention to the quality of soldering during the building process.

The first step to a high quality soldering job is the proper materials, and tools. Without the correct tools to do the job you go from being a winner to a loser. A high quality soldering iron is the place to start. You will need at least a 45 watt soldering iron, we recommend an Ungar 45 watt integral tip soldering iron. We also recommend 98-2 solder (98% tin and 2% silver) as the best solder to use, it is lighter, stronger, and easier to flow. You will pay a little more for this kind of solder but a 1 lb. roll of solder will last you almost forever (at least 100 or more cars). The only flux we recommend is stay bright brand. This flux will etch the steel thoroughly to allow the solder to bond completely. A nice thing to have is a flux dispensing bottle, one with a Teflon, or stainless tip which allows for more exact placement of the flux. You will also need a good soldering sponge, a block of Salamoniac, a toothbrush, dawn dish washing soap, and NEVERDULL brand polish (do not use any thing but NEVERDULL). Make sure that you are soldering in a well ventilated area and use safety Goggles.

If you are starting off with a brand new iron you will need to take a few steps to ensure a long life and better results from your investment. You need to tin your iron by plugging it in and allowing it to heat up. After approximately 30 to 90 seconds the iron should be hot enough to tin, so place a small amount of solder on the tip as soon as it will melt. Once you completely cover the iron with solder then wipe on your wet sponge till clean. If you wipe the tip of the iron on the Salamoniac and load it with solder it will make tinning a lot easier. If you do not get the tip completely tinned on your iron it will not last as long. This happens because the flux will eat through the plating and in to the core. Also you will not want to leave it plugged in for long periods of time as it will burn the tip. If you need to keep it hot for a race then keep plenty of solder on the tip to keep it from burning up.

For this discussion we will assume you are assembling the pillowblocks to a chassis. The first thing you will want to do is to prepare the surface you are going to solder. Take your Dremel Moto-tool with a sanding drum and lightly sand off the bluing from any point you plan to solder. Then on the bottom of the pillowblocks (or any where the laser or edm has cut) you will need to lightly grind with a Dremel cutoff wheel, but only until shiny. If you do not get this area clean all the flux in the world will not etch the surface enough to make the solder attach. Now place the pillowblock in the pillowblock slot, the fit should be snug. This is to keep the upright vertical. Also when hit from behind or in a corner the tight fit of the pillowblock will keep it in place and not allow it to break the solder and roll out of the joint.

Next you will want to place flux on the area to be soldered. Use only enough flux to wet the area you are going to solder but, do not use an excessive amount and get it all over the chassis. Flux is an acid that will cause oxidation and rust. When heated it etches the metal and allows the solder to bond to the steel. The flux will also allow a better heat transfer between the iron and the steel thus allowing the solder to flow faster and smoother.

Now wipe the tip of the iron on the sponge to get it clean, add a small quantity of solder to your iron. Place the tip of the iron at a 45 degree angle from the base of the work piece and along the seam of the chassis and the pillowblock. Slide the iron along the seam slowly and then remove the iron from the work piece. While the steel is still hot add a little more flux to the area to be soldered (being very careful not to inhale any fumes). Now repeat the process until the solder flows evenly around the entire joint. Remember to use as little solder as necessary to do the job as solder can quickly add up to be a lot of weight. The next step is to do the bottom of the chassis. While still hot add flux to the bottom of the pillowblock hole. Wipe solder on the pillowblock area and hold the iron on the area until the solder stops bubbling. If you get any pinholes in the solder just add more flux and re-heat the solder. Any pinholes in the solder will give your chassis a place for rust to start.

The last step is the most important to the long life of the chassis. Take the chassis and wash in hot water completely using the soap and a toothbrush. Be sure to get to every nook and cranny. Then when you have completely rinsed and dried the chassis thoroughly use a small amount of NEVERDULL and rub down the chassis until the discolored flux is removed and wipe off the residue. The NEVERDULL will prevent rust by removing the residue flux from under the discolored bluing and also leaves a protective coating on the steel. NEVERDULL is available at most hardware stores, truck stops or auto part stores. It also is known as magic wadding polish. It used to be made by themselves but, now has been acquired by the eagle one polish company. If you have access to a wire wheel with a fine wheel you can wire wheel all the joints to further improve the appearance of the chassis before using the NEVERDULL.

If you take the time to follow these recommendation’s on soldering you will find that you will produce a high quality Racecar that will not break apart in the first wreck. You may not be able to produce the professional results immediately but with practice you too will be soldering like the pros.

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