All drilling operations should start with a center drill; this gives an accurate and clean starting point, and reduces the chance of the drill bit "walking" off center.
A quick way to set the lathe cutter bit on center:
Cut a strip of sheet metal about 1/2 inch wide and 6 or 8 inches long. Bring up the cutter with the cross feed to the work and then clamp the sheet metal strip gauge between the cutting edge of cutter and the work. If the cutter is on center, the gauge will lean toward you. If the cutter is above center, the gauge will lean away from you.
This is real time save and quite accurate.
- Gordon W. Corwin
- 6986 Church Street
- Highland, California
Take a slice of metal of the same diameter as the work and center-drill it in the lathe. This can be put on top of the work in a machine vice and will act as a guide. This will also work for square stock. From "Cross Drilling" by Stan Bray, "World of Model Engineering" No 3, 1989, http://www.model-engineer.co.uk/sites/7/documents/wome-3-pt3.pdf
Lathe Tool Angle Chart
See Cutting Angles of Tool Bits.
Lathe Tool Angle Chart by H.J. Coventry. From "The Miniature Locomotive", Nov-Dec 1953.