Hydraulic Die Forming Discussion Group
Re^3: EASY,EASY Anticlastic Stake Preparation

Jack Berry
berry2000@prodigy.net


Hi Anne. I think we have a slight misunderstanding. When I slide the delrin rod into the spinning rasp bit, the rod is continuously rotated which defines the curved axis perpendicular to the length of the rod. At no time is the rod held still while in contact with the bit - a situation which would grind a "straight bottom" as you said. In fact, if the depth of bite is held constant while rotating the rod the curvature of the axis perpendicular to the rod length will be identical to the curve of the uncut rod but displaced by the depth of cut. You can change this axis curvature by using a rod of a different diameter (easiest) or by varying the depth of cut while moving through the rotation. For example, going deeper at the center of the rotation will give a "flatter" curve.    ....Jack

On Sat Aug 17, Anne Hollerbach wrote
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>Jack,

>that's a terrific discovery! The only thing I would add would be a suggestion to take a circular file [round wood rasp or chain saw file] and significantly ease the bottom edges of each indentation. You literally create an anticlastic shape in the stake -- the bottom of the slot should fold around the center of the stake and the sides should scoop upward. What you don't want is an indentation with a straight bottom running perpendicular to the length of the stake. This will damage anything you want to form in it.

>So use the drill press to shape the X axis, and a round file or rasp to shape the Y axis, and away you go!
>Very nifty indeed.
>

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