The Raytech Hand Piece Modification

AKA the RayDial

  Click for a large photo

The platform machines, like the Raytech have an entirely different geometry of stone movement and angle of cut indication than the more popular mast type machines.  

With a mast machine, any dial indicator or other method of showing movement is measuring radial movement of the dop arm, and doesn't really measure the depth of cut, but indicates a translation of radial movement.  IE at 90 degrees, a 0.001" indicated movement translates to about 0.005" of stone movement. (a 1.5" to 7.5" lever arm ratio or 5 to 1 ratio).  When you approach 0 degrees, the depth of cut measured changes drastically.  You are cutting near the tangent of the arc defined by the dop arm.  A 0.001" indication on the dial might  be less than the 0.001" read on the dial. However, the cam action you apply at these very low angles and  the spring of the mast makes it very difficult to get an accurate angle on the cut.

With a platform machine, there is considerably less variation on the ratio of movement.  With the RayDial, the ratio of indicated movement vs actual movement of the stone ranges from 1.6 at 90 degrees to 1.2 at zero degrees.  IE at 90 degrees, 0.001" on the dial will mean the stone has moved 0.0016".  In all instances, the cut angle, when the dial reaches the zero indicated movement, will be exactly the angle you set.   You are measuring a movement that is not dependant on the angle you are cutting.