# Starting position and drilling depth

Using stop rings, you can define the following parameters:

- Starting position of the drill bit

- Drilling depth

Pos | Part | Function
--- | --- | ---
1 | Starting position ring | Defines the starting position for drilling. This allows for quick positioning of the drill bit at the pre-defined safe distance to the surface. The starting position can be adjusted.
2 | Depth ring | Defines the drilling depth.
3 | Depth valve | Controls the drilling depth. Once the depth ring reaches the valve, it activates the valve, and the spindle retracts into the starting position. The motor automatically switches off after retract.
4 | Starting position valve | Controls the starting position for drilling. Once the starting position ring reaches the valve, it activates the valve that switches off the motor.

You can calculate the distance between the depth ring and the drill head (dimension L in the figure below) for the desired drill depth D according to the following formula:

L (mm) =D (mm) – 31.0 mm

L (in) = D (in) – 1.2 in