Scherk intro

Mike Foster of Vermont first conceived and developed the techniques for turning a wooden construct that he calls a “Scherk Tower”.  He is also the first turner to complete the turning of a Scherk Tower.

The Scherk Tower is based upon Scherk’s Second Surface which is defined as a “surface that looks globally like two orthogonal planes whose intersection consists of a sequence of tunnels in alternating directions. Its intersections with horizontal planes consists of alternating hyperbolas” which looks something like this.

 

Scherk 01 thumb

From the first time I saw a picture of one of Mike’s Scherk Towers, I had the desire to turn my own so I contacted him and he generously offered advice as to how I should go about turning one.

 

The following are the steps I used to turn my Scherk Tower which I called Lacewood Scherk.

Start with a perfectly square blank with all four sides at right angles to one another. This is important for alignment purposes when boring tunnel holes.  My blank was 3 ⅜” square and 7” long.  Next I found the exact center of all four sides and scored a line with a marking gauge from top to bottom.  I scored the line using both adjacent faces on all sides to make sure I had the center.  Next on the face that was to be the “front” of my Scherk Tower I measured the length and found the exact center from top to bottom and marked that location.  I chose the sides of the lacewood blank with the most medullary ray/grain exposure to be the front and back of my tower.

In total my Scherk Tower has five tunnel holes passing through it.  There are three tunnel holes that pass from front to back and two tunnel holes that pass through the sides.  I decided that I would start with a ¾” bored hole as the basis of the tunnels for my tower.  In order for the holes to pass over each other there must be a wall thickness that has to be taken into consideration as part of the layout.  I arbitrarily assigned a desired ¼” wall thickness to be between the tunnel holes.

So I marked my first hole in the center of the “front” side at the 3 ½” location in the exact center from top to bottom and side to side. Next I rotated the blank to one of the adjacent sides and measured 2 ½” from the top and made a mark and then measured 2 ½” from the bottom and made a mark on the center line that I had scored earlier.  The attentive reader will notice that the difference between these centers is 1” (¾” tunnel hole diameter + ¼” wall thickness). I then rotated the blank back to the “front” side and measured 1 ½” from the top and bottom and made marks.  These tunnel holes will be separated by 1” (¾” hole diameter + ¼” wall thickness) from the holes located below them in the adjacent sides. In the picture below the reader might note that there were other location marks for tunnel holes that were being considered but ultimately discarded.

These marks locate the 10 different axes upon which the blank will be located for boring and turning.  But how is that possible you ask?  The blank will be located with stop blocks and when the blank is turned over the turning can be bored and turned at exactly the same place on both sides.

Scherk 02 thumb

 

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Monday the 25th. Thanks for visiting Woodturners Unlimited.