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- Feb 1, 2012
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- 13,727
It's for cutting a mortise pocket in the top of a window frame. A pulley was set in this pocket. It was strung with a counterweight to make it easy to raise ans lower a single hung window (top pane is fixed, lower pane raises and lowers).
There should be gears attached to each of the drill points. The center drill is direct drive. The other two bits will be reverse cutting. As the center bit cuts in the forward direction the gears turn the other two in the opposite direction.
If you have some AeroKroil and some patience I'd like to see the inside of that thing.