When I buy my high speed steel, 90 degree, under-cutting burs I always think of the words, “waste not, want not”. This little phrase has stuck in my mind for many years. If I find that some of my burs are getting past their prime then I examine each of these well used cutting teeth and decide if I should re-sharpen them. Some of my burs are $10.00 to over $15.00 per unit so why throw it away if it’s only slightly worn down?
The one problem in re-cutting burs is that the overall size is not the same as before re-sharpening. This however is no big deal. Why you say? The bur I’m resharpening now will become a size smaller, but when I resharpen the next larger bur, it will become the size that the bur I’m sharpening now was.
To resharpen the burs, I use my carborundum wheel to individually recut the very outside edge of the teeth. This may seem like a tedious chore, but after a short time you will develop a “feel’ for cutting the teeth and extend the use of your burs for many more months of hard work.
This method of re-cutting is not to be used for the 156C burs as their teeth are too close together. It can be used with the High Speed Steel 90 degree angle bur. This bur has its teeth a bit farther apart, and this “open tooth” spacing, is adequate for what we need for this procedure.
To recut the teeth, use a very thin carborundum wheel. Carefully thin out the edge of this wheel and proceed to touch only one tooth. Why? This way you can see if the new cutting angle is the same as what’s on the older bur. Hold the bur with your left hand and rotate it slowly keeping your hand and wrist supported and the elbow rigid. Once this re-tooling section has been accomplished, proceed with the next group of teeth. Now with greater care, start at the “pavilion” of the bur and work “outwards and upwards” towards the actual cutting area of the bur.
Then invert the bur and recut the teeth on the “crown facet” area of the bur. As before, cut the upper section of teeth one at a time, working towards the outside leading edge of the bur.
In a few minutes of very careful cutting, you now have a brand new bur, slightly smaller mind you, but it’s good for many months of constant use. Till the next time!