A depth limiting device for a drill includes a main body, an axial braking structure, and a limited shrinking structure. The axial braking structure is attached to the main body. The limited shrinking structure surrounds a drill rod of the drill, is slidably attached to the main body, and is in a home position or a compressed position. The axial braking structure axially brakes the drill rod such that the drill rod moves together with the depth limiting device. When the drill rod enters into a subject, the limited shrinking structure is pressed against the subject, moves from the home position to the compressed position, and stops the drill rod from entering further into the subject.

A position controlling device for a carpenter angle drill/hollow chisel mortiser has a mounting group, a positioning group, and a retaining arm. The mounting group has two crossbars and a bridge bar. The bridge bar is connected to the crossbars. The positioning group is connected to the mounting group, and has two limiting blocks, a holding frame, and a circuit breaker. The limiting blocks are connected to the bridge bar between the crossbars. The holding frame is securely connected to one of the limiting blocks. The circuit breaker is mounted in the holding frame and has a contacting slice and an electric wire. The contacting slice is elastically connected to the circuit breaker, and transversally extends out of the holding frame. The retaining arm selectively abuts the contacting slice of the circuit breaker to enable the circuit breaker at a turn-off condition.

A position controlling device for a carpenter angle drill/hollow chisel mortiser has a mounting group, a positioning group, and a retaining arm. The mounting group has two crossbars and a bridge bar. The bridge bar is connected to the crossbars. The positioning group is connected to the mounting group, and has two limiting blocks, a holding frame, and a circuit breaker. The limiting blocks are connected to the bridge bar between the crossbars. The holding frame is securely connected to one of the limiting blocks. The circuit breaker is mounted in the holding frame and has a contacting slice and an electric wire. The contacting slice is elastically connected to the circuit breaker, and transversally extends out of the holding frame. The retaining arm selectively abuts the contacting slice of the circuit breaker to enable the circuit breaker at a turn-off condition.