Tricks For Precurving Files

Greeley, CO...June 17, 1994

What do a flagpoles, a fishing rods and an endodontic files have in common?

They all are applications of the notched beam concept.

There is a principle in engineering called the notched beam concept.

If you bend a beam the metal gets compressed on the inside of the curve and stretched on the outside of the curve.

This applies to all kinds of metal beams small and large.

You may have noticed that flag poles, light poles, buildings and fishing poles are tapered.

This is done to distribute the stresses throughout the entire length of the beam.

If you permanently bend a beam at any point or if you cut a notch in the beam, all the stress and distortion of bending is concentrated at that point.

This is why you must discard any file that has a permanent distortion in it.

Or as my good friend Dr. Kit Weathers says, "Use a file one time less than it takes to break it."

If you attempt to pre-curve a file by using a hemostat or a pair of pliers,you only succeed in putting a multiplicity of small permanent bends in the file, any one of which can receive all the stress and can break at that point.

If those small bends are continuous then each takes its share of the stress and the file can bend without breaking.

Here's a video of the process.

The method we use is:

The result is a curved file with no sharp bends.

And it is easy to do.

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