16 March 2015

A popular method of connecting your motor lead wires to the braid in your guide is to use small Allen (hex head) type screws.
Simply called the "Set Screw Connection", when it is done properly it provides a very reliable connection.

This method has been around a long time and some companies like Slot.it use it in their ready to run models. It creates a very secure connection that I prefer over using the press-in ferrule method.

The only drawback to it is that it can actually damage the wires you are trying to secure. As you install the screw, these same threads that help provide a solid connection can cut the small strands your wire is made up with and results in a weaker connection.

My solution is to "tin" the lead wire ends first to strengthen them. Here is a quick link on tinning.

If you are familiar with this method then you can just scroll down and quickly you will see my approach. Pretty simple, just tin and flatten.
But there are some that are new to our hobby so I want to discuss it more in depth.

The following is a reference list of the parts I use.
You might have your own sources for these items. Please disregard if you have your own source/brand.
They are listed as a courtesy for newcomers and for reference.
These are the part numbers/brands I use and therefore featured in the article.

Suggested List Of Materials
Slot Car Corner 22 AWG Ultra-Flex Silicone Insulated Stranded Wire
Slot Car Corner 3 MM M2 Set Screws
Slot Car Corner Braid (Tinned or Untinned)
Suggested List of Tools
Soldering Iron
Rosin Core Solder
.9 MM (0.35") Hex Driver
8" Linesman Pliers

For this method to work properly, you need to try and use the correct size and type of wire.
Too small of a diameter will lead to reduced current flow and strength.
Too large a diameter will result in fitment issues. There is not much room where this wire must go.
Combined with the screw that creates the pressure inside the guide, 22 AWG is as large as you need.
For our regular "home" type motors, you don't need any larger diameter wire.
22 AWG is ideal for the low amperage draw these motors have.

You also want a wire with a flexible insulation coating.
Silicone is ideal for this. Silicone coated wire is primarily designed for rapid and repeated movement.
You want your guide to turn as freely as possible, so reducing any binding when you can is highly advised.

Before you trim your wire, take a little time to see how much you need to remove.
This is not that critical of a step, but gives you a cleaner appearance.
I use the guide as a guide.

Slot.it & ScaleAuto guides shown for reference only. Measure the guide you will use accordingly.
Measure the front bulkhead of the guide as shown. This will tell you how much insulation you need to remove.
You do NOT want the wire going all the way through the guide bulkhead and sticking out the bottom. That is why I suggest this step.

Now that you know how far to trim, let's trim away. As you can see from the photo above, I removed approximately 3 mm of coating.
Now you can TIN the end of the wire. Remember, just a slight amount is needed to flow into the wire.
Once you have tinned the wire, use your pliers and flatten the end as shown below.

Your wire end should look very close to the above photo. The wire is now ready for installation.
In most cases I always prefer to install the braid and wire while the guide is removed from the car.
I just find it much easier to work with in this manner.

Once you install your braid, use a toothpick or like item to form the braid inside the bulkhead. This helps ease the installation of the set screw.

Installing the wire is easiest when the guide is removed from the car. It requires a fair amount of pressure to get the screw started but not anything excessive.
One thing you want to do is to try and hold the wire as centered as possible with one hand while inserting the screw.
Sometimes it will move to one side a little, but usually that does not hurt anything.
As long as you have a good contact area between the wire and the braid, you will be fine.

I installed and then removed a wire to show you how the screw threads into the tinned wire. You can see the threads it cuts, but it does not cut through the strands.

This is what the finished wire installed looks like.
Hope this small tip helps some of you.

- Harry
Feel free to contact me about this article or just our hobby in general.

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