Cause & Effect Connection - The Key to DESIGNING Multiple Axes Pieces
The Masai Herdsman pieces are great for introducing the link between Multiple Axes Effect and Cause.
The head's cross section is basically TRIANGULAR - THREE intersecting ARCS, turned on THREE AXES , all turned to the same diameter and whose centers are equidistant from the blank's center. WHERE you place the centers of the three arcs gives you a lot of options for the shape of the head, as you can see in the following illustration. And because you can make the triangular cross section asymetric you can give the head a definite front, sides and back. That means you can make the head face in any direction you want, relative to the torso.
The neck and legs cross sections are ROUND, turned on the blank's centerline and are tapered - all familiar to single axis spindle turning. It's the long thinning taper of the legs that can create a strength problem when refining the proportions of the piece iteratively - as we shall see.
The torso's cross section is LENS SHAPED - two intersecting arcs, turned on two axes. Like the triangular "head" , the torso has direction - a front and back - and you've got a lot of cross section options.
While turning a multiple axes piece, you usually have to figure out how to go from what you've got to what you want, In this next illustration, on the left we have What We've Got - and on the right What We Want.
What We've Got is rather squat and thick. What We Want is for the piece to be tall and narrow.
So let's work out how to get from HAVE to WANT.
On the left of the following illustrations are the centers and diameters we turn to. To the right, the results.
To make the head thinner, we turn on the centers of the three interesecting arcs that create the triangular head.
BUT, ON EACH AXIS, WE TURN ONLY HALF OF THE DIFFERENCE BETWEEN "HAVE" & "WANT".
Remember, we're playing with three INTERSECTING arcs. Change one arc and you affect the location of where it intersect the other two arcs. Multiple axes turning is similar to playing chess - planning two, three or four moves ahead - before making a move.
To make the torso thinner and narrower, on each of the two intersecting arcs, we need to turn off HALF of the DIFFERENCE between HAVE & WANT.
Look at the circles and centers in the illustration above - and then at circles and centers in the illustration below. Note that to narrow the width and depth of a cross section of the torso, the centers are the same, but the diameter of the circles merely get smaller (we turn off more wood on each axis).