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Magnet matching & measuring

In this article I'll explain what the need is for matching your motor or traction magnets and how to measure there strength.

There are various ways to measure magnet strength from the cheap to the expensive. A professional gauss meter will measure your magnets to their exact gauss reading and are very accurate. The scientific grade versions are very expensive (£200 plus). For the purpose of HO slot cars the cheaper methods more than suffices for our hobby. Probably the cheapest option is to use graph paper and a compass, to build a DIY Gauss meter or using weighing scales, which I’ll explain here.

I discovered the scales method thanks to an article on the Slot Car Monster website. Firstly you will need an On Balance Kilo Miniscale DK-1000 model weighing scale. It must be this model as the weighing plate consists of metal that attract magnets. This can easily be found on ebay for approx £8.

Then you need to carefully drill two holes in the plastic cover/tray so that you can access the on button and the tare button. The reason for this is that the scales will turn off after 60 seconds as they believe they are not being used. By drilling the holes you can use pen tip or small pointy object to turn the unit back on without having to remove the tray all the time.

Then once this is done mark an area on the plastic cover/tray with a permanent marker, mine is over the logo.

Now rest the scales on a flat table and turn them on. Wait for it to zero and then select what you want to measure your magnets in using the tare button, I choose Gr for grain

Place you magnet on the area you marked out on the cover/tray and you should see a minus reading (this is because the magnets is trying to pull the metal weighing plate towards it so it reads as a negative as opposed to a positive).

With a fine tipped permanent marker write the reading on the rear of the magnet.

After you have measured all your motor and traction magnets you will then want to pair those that are closest in strength, this is called matching. Ensure that you pair them so each pair has one north and one south magnet. They should naturally be attracted to one another.

Once you have done this you will want to pick the pair that are the closest and highest in strength for your chosen number 1 race car.

- Robin Cornwall

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