A sewing machine includes a needle bar, a needle bar release mechanism, a drive portion, a contact member, and a switching mechanism. The needle bar is configured to move up and down. The needle bar release mechanism is configured to connect and disconnect the transmission of the driving force between the drive shaft and the needle bar. The drive portion is configured to drive the needle bar release mechanism. The contact member is configured to come into contact with the needle bar in a case where the needle bar is positioned at a top dead point of the range within which the needle bar is able to move up and down. The switching mechanism is configured to switch the position of the contact member between a first position and a second position.

A spar for a propeller blade comprises central structural member extending from a root to a tip of the spar. A first portion of the central structural member extends from the root of the spar and a second portion extends from the tip and adjoins the first portion. The central structural member includes a first plurality of plies of composite material on a pressure side thereof and a second plurality of plies of composite material on a suction side thereof wherein the first plurality of plies are in contact with the second plurality of plies in the second portion from a leading edge to a trailing edge thereof. A plurality of yarns extends through the central structural member in at least the second portion.

A spar for a propeller blade comprises central structural member extending from a root to a tip of the spar. A first portion of the central structural member extends from the root of the spar and a second portion extends from the tip and adjoins the first portion. The central structural member includes a first plurality of plies of composite material on a pressure side thereof and a second plurality of plies of composite material on a suction side thereof wherein the first plurality of plies are in contact with the second plurality of plies in the second portion from a leading edge to a trailing edge thereof. A plurality of yarns extends through the central structural member in at least the second portion.

A sewing machine includes a needle bar, a needle bar release mechanism, a drive portion, a contact member, and a switching mechanism. The needle bar is configured to move up and down. The needle bar release mechanism is configured to connect and disconnect the transmission of the driving force between the drive shaft and the needle bar. The drive portion is configured to drive the needle bar release mechanism. The contact member is configured to come into contact with the needle bar in a case where the needle bar is positioned at a top dead point of the range within which the needle bar is able to move up and down. The switching mechanism is configured to switch the position of the contact member between a first position and a second position.

A sewing machine assembly includes a sewing machine frame, a needle bar, a drive shaft, and a vibration dampener system. The needle bar configured to linearly reciprocate relative to the sewing machine frame along a needle bar axis. The drive shaft is coupled to the needle bar and configured to rotate about a drive axis to drive linear reciprocation of the needle bar along the needle bar axis. The vibration dampener system is coupled to the drive shaft to reduce vibration of the sewing machine assembly caused by linear reciprocation of the needle bar during use of the sewing machine assembly.

A sewing machine assembly includes a sewing machine frame, a needle bar, a drive shaft, and a vibration dampener system. The needle bar configured to linearly reciprocate relative to the sewing machine frame along a needle bar axis. The drive shaft is coupled to the needle bar and configured to rotate about a drive axis to drive linear reciprocation of the needle bar along the needle bar axis. The vibration dampener system is coupled to the drive shaft to reduce vibration of the sewing machine assembly caused by linear reciprocation of the needle bar during use of the sewing machine assembly.