Need to work with a toroidal coil? The following toroid-cutting tips will help you prep for circuit deployment.
First, pick the correct ferrite toroid for your application, put the windings on, and secure it in a vise (do not over tighten). Consider using small sheets of aluminum, a soft metal, to prevent damaging the toroid.
Using a Dremel or similar tool equipped with a cutoff disc suitable for cutting metal, start cutting at a right angle w.r.t. the toroid. Safety glasses are required. Small pieces can chip from the ferrite as well as from the disc.
Go slow! It can take about 3 to 4 minutes to get this far. The rpm should be quite high, but not exceeding the disc’s maximum rated rpm.
Adjust the toroid so that your second perpendicular cut can be made easily. Be careful: the toroid loses its rigidity when cut, and the material is quite brittle.
Take your time and be sure not to force your way through, as the cutting disc is not suitable for grinding and prone to breaking when pressure is applied perpendicular to the disc radius.
Done! Be careful, the toroid may be hot from the cutting. Again, be gentle while handling the cut toroid, as it’s quite brittle and breaks a lot easier than when in its closed toroid form.
This article first appeared in the January 2013 edition of Elektor (120717). CircuitCellar.com is an Elektor International Media publication.