When mounted on a twist drill, the GN-Gratex II serves as a deburring and chamfering tool. Depending on the circumstances, it might be used in combination with spacers to create countersinks.
The GN-Gratex II is designed for spiral drills of type N. The use in combination with other types is restricted. By default the chamfer has an angle of 90°. If required, other angles can be produced. If there are any questions,
When inserting the twist drill into the GN-Gratex II-tool, make sure that the cutting edges of the GN-Gratex II just butt against the chamfers on the back of the spiral drill. The two screws are used to tighten the GN-Gratex II und fit into the flutes of the drill.
After roughly locating the GN-Gratex II by tightening the screws, the fine adjustment is made using the depth gauge of the drill spindle. Because the dimensions of a drill's back end aren't standardized, the GN-Gratex II might not fit on every brand of drill. In this case the arbor hole of the GN-Gratex II should be reground to adapt to the drill's diameter.
GN-Gratex II for spiral drills is suitable for all common machinable materials. When creating blind holes, especially in materials creating long chips, the evacuation of chips might be difficult. This may be avoided by emptying the flutes of chips frequently and adding a lubricant solvent.