Turning

Subject:
tool/work piece vibrations

Doug Dubowski
I am making some wooden mallets and have come across a vibration issue that leaves a series of helical "ruts" in the work piece. These ruts can run for a couple of inches along the length of the turning and also on faces of the turning perpendicular to rotation of the piece. The piece of wood is about 14" in length in total, with the actual mallet being around 10" in length, 2 3/4" in diameter at its widest point and the handle consuming almost half the length at at diameter of 1 1/2". I assume it is a vibration and resonance issue, but the piece is too small in length for a spindle steady rest. I only know they are there because the tool starts to chatter (and it can be a variety of tools - it happens with bowl gouges, spindle gouges and skews). The wood is kiln dried maple.

Once these ruts are created, they are a pain to get out - I have to essentially take a deeper cut to simply get beneath them, but am not sure how to avoid them in the first place. Should I be increasing/decreasing the speed (to avoid the resonance) and if so which is the preferred direction - up or down in speed? At the moment I am turning around 1500 - 1700 RPM. Am I exerting too much or too little pressure on the wood with the tool?

Any ideas as to how to avoid, much appreciated.

Doug

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