Page 114 - HOLE MAKING CATALOG p185-310

GUNDRILLS When using a gundrill on a lathe machine, a USER GUIDE
short solid carbide centering drill should be Drill Penetration Instructions
used prior to the gundrill. Once the gundrill
enters the pre-drilled hole, it is self-guided. 1 Rotate the drill counterclockwise prior
to and during hole penetration
1 Drilling a pre-hole (drill diameter +0.02 mm)
2 Stop the drill rotation and start the coolant
Never try to penetrate the workpiece by using a gundrill
3 Rotate the drill clockwise prior to drilling operation
2 Gundrill penetration through the pre-hole
The influence of a Tool vs. Workpiece rotation
A shallow pre-hole can’t lead the unbalanced gundrill
Rotating tool Rotating Rotating tool
workpiece & workpiece

2 x D min

Worst Medium Best

The maximum misalignment between the

drill bushing and the workpiece center line

should not exceed 0.02 mm (.0008”).

Rotating Workpiece

Bushing

Stationary Drill

Max.
0.02 mm
.0008"

298 ISCAR