US Patent 8684641 Locking hole saw collar

An assembly includes a hole saw, an arbor, a collar and a nut. The hole saw is formed from a back plate and a skirt which has a cutting edge on its free end. A passageway is provided through the hole saw. The arbor is rotatably mounted to the hole saw and extends through the passageway. The collar is nonrotatably mounted on the arbor. The collar has a protrusion extending from an end face thereof. A nut is rotatably mounted on the arbor. The collar is trapped between the nut and the hole saw. The nut directly bears against the end face and the protrusion of the collar, which causes the nut to cock relative to the collar. As a result, the nut does not easily come loose on the arbor, even during aggressive use.