Michael L Overmyer

US Patent:

51526417, Oct 6, 1992

Filed:

Oct 15, 1991

Appl. No.:

7/776836

Inventors:

Michael S. Overmyer - Millbury OH
Thomas A. Peitz - Sylvania OH

Assignee:

Royal Tool, Inc. - Toledo OH

International Classification:

B23B 3500
B23B 4100

US Classification:

408 1R

Abstract:

A method and apparatus for controlling glass drilling in which the starting position for the drill bit is calibrated prior to drilling. The drill bit is initially spaced close to the surface to be drilled and the rotating bit is slowly advanced toward the surface while a cooling fluid is discharged through an axial passage through the bit. Contact between the bit and the surface is determined by sensing either an increase in the fluid back pressure or a decrease in the fluid flow rate. The determined bit position is stored and used as a starting position when subsequently drilling holes. The starting position may be modified for subsequent workpieces to compensate for bit wear.