Drilling triangle holes 1a

According to The Wolfram Demonstration Project
Oval rotates inside triangle.
Loci of various points on the oval are shown.
The red locus is the section of the drilled triangle hole.
Its corners are sharp.
An inscribed round hole of the triangle hole must be predrilled.
For more see:
http://meslab.org/mes/showthread.php?p=111832#post111832

Inventor files of this video:
http://www.mediafire.com/file/6y63lfxle80v343/DrillingTriangleHole1abInv.zip/file

Видео Drilling triangle holes 1a канала thang010146