A drive system for releasably interconnecting a motor shaft of a rotary hand held power tool and an input shaft of an attachment device. The system includes an elongated flexible drive shaft connected to the input shaft, wherein the flexible drive shaft has an outer end portion with a non-circular cross-section configured to engage a complementarily shaped cavity of an output shaft operatively attached to the power tool motor shaft, where the output shaft has a generally cylindrical outer configuration along its length and a rearward mounting portion for attachment to the motor shaft, an intermediate portion having the complementarily shaped cavity for receiving the flexible drive shaft and a forward portion with an enlarged concentric opening for receiving and guiding the outer end portion of the flexible drive shaft into the cavity during mounting the attachment device on the power tool.