Abstract: An adjusting device includes a positioning member, a driving member attached to the positioning member and including an indicating block, a moveable member, and a resilient member. The moveable member is slidably attached to the positioning member and includes a receiving portion. The receiving portion includes a plurality of graduations. The indicating block extends through the positioning member and is received in the receiving portion. The resilient member is received in the receiving portion. The driving member drives the moveable member and the retaining member from a first position to a second position. If the moveable member and the retaining member are in the first position, the resilient member is uncompressed, the indicating block is away from a predetermined one of the plurality of graduations. If in the second position, the resilient member is compressed, and the indicating block is level with one of the predetermined graduations.