|Project by Dave Hair||posted 09-12-2013 04:12 PM||4355 views||28 times favorited||30 comments|
My cosine wave table was inspired by the wonderful work done by Nico Jose (see http://lumberjocks.com/projects/46821 ). He is an artist and I am a copycat, with modifications.
I used the cosine of every 5 degrees from 0 to 60 degrees as the distance from the origin (left or right end of the table) multiplied by the length of the top piece of wood to generate the wave shape. In other words, cosine of zero degrees is 1.0000 so the X-axis shift is 0.0. The cosine of 60° is 0.5000 so when multiplied by the width of the top (20” = 508 mm), gives an X-axis shift of 254 mm (or half way across the top). I worked in millimeters, finding it easier to to calculate in a spreadsheet than inches and fractions.
Angle COS mm from front edge
0 1.0000 0.0
5 0.9962 1.9
10 0.9848 7.7
15 0.9659 17.3
20 0.9397 30.6
25 0.9063 47.6
30 0.8660 68.1
35 0.8192 91.9
40 0.7660 118.8
45 0.7071 148.8
50 0.6428 181.5
55 0.5736 216.6
60 0.5000 254.0
Simply by flipping a second build of triangles one can complete the sequence to the back of the table. This particular table took four triangle sets to complete.
The woods that I selected are mostly the ‘common’ exotics like paduak, holly, sapele, purpleheart, canary wood, wenge, bloodwood, hickory, wormy walnut, ambrosia maple, mahogany, leopardwood and red palm (marvelous, splintery stuff).
I really liked Nico’s gaps in the top pieces, so I copied that too.
The pieces are held together with glue and pin nails. I had a great deal of mental difficulty staggering the ends of the tops (see the images) and also getting the angles of each piece correct. The spreadsheet that I used to calculate all of trigonometric requirements never quite matched the workshop reality.
However, without the Kreg miter gauge on the tablesaw, I don’t think I could have built it. That miter gauge was rock solid and right on. And making sure the tablesaw blade was truly vertical was absolutely essential (preaching to the choir here).
So it is sitting in a fairly dark room out of any hope of sunshine to avoid the fading of paduak and purpleheart for as long as possible.
Thanks again to Nico’s creativity.