Abstract: A looper drive assembly for a buttonhole sewing machine includes a long arm which is driven by a double cam, followers and an oscillating plate at one end and the arm generally reciprocates longitudinally. V-shaped plates are pivoted at a second end of the arm. Ends of the V-shaped plates are connected to rocking links which carry the looper needles. The links are pivoted on shafts and support the V-shaped plates and the second end of the arm. As the arm reciprocates, the V-shaped plates swing, pull and push lower ends of the link and oscillate the links around shafts for alternating engagement of the looping needles with thread carried through a fabric by a main needle.

Abstract: Bight stitches at sides and bar tack stitches at ends of a buttonhole site are formed by periodically oscillating a needle bar holder over lesser and greater angles while a needle is in an up position. The needle bar holder is fixed to a horizontal transverse shaft. One end of a long, generally vertical arm is clamped to the shaft, and a generally horizontal link is pivoted to a lower end of the arm and to an adjustment slide in an upper arm of the inverted Y-shaped follower plate. The Y-shaped follower plate is pivoted on a central horizontal pivot. A double cam engages cam follower rollers oppositely extending from lower ends of the Y-shaped follower plate. Periodically, while the needle is up, the cams move the follower plate back and forth.

Abstract: A stop cam is positioned on the main drive shaft of the buttonhole sewing machine. A stop lever moves axially between an engaged and a disengaged position. A heavy compression spring absorbs machine kinetic energy when the stop lever is in contact with the stop cam. A slide bar is positioned on one side of a lower end of the stop lever to hold the stop lever away from the stop cam. A spring positioned on the stop lever, opposite the slide bar, moves the stop lever into alignment with the stop cam. The tripping of a pedal moves the slide bar away from the stop lever thereby allowing the spring to move the stop lever into an engaged position. After substantial slowing, reaching the maximum displacement and spring loading, the cam presents a low flat surface to the stop lever. The spring pulls the lever against the flat and any remaining kinetic energy is too little for the cam to continue turning and raise the stop lever.

Abstract: A counter-weighted eccentric or crank is clamped to an end of the upper drive shaft. A link is pivoted between the eccentric and an end of a short leg on a V-shaped rocker. The base of the V-shaped rocker is pivoted on a fixed pin. The long arm of the V-shaped rocker is connected to a needle bar to drive the needle bar up and down. The movement of the needle bar carries a main needle and thread through a workpiece to make stitches in the cloth.

Abstract: A double cam drive operates on a main drive shaft of a buttonhole sewing machine is disclosed. Three double cams are arranged sequentially on the main drive shaft. A first double cam operates a looper mechanism, a second double cam drives a feeder, and a third double cam drives a needle bar mount for operating a bite mechanism to deflect a needle housing to make side stitches and tacks. Each double cam has a cam collar and two generally-circular concentric cams. Each cam of a double cam is positioned off-center on the cam collar with one cam positioned opposite the other. The three double cams have mounted collars at axial ends for securing the double cams to the shaft. Spacers are positioned between any two adjacent double cams for creating the proper spacing between the cams. A follower plate is pivoted on a stub shaft and has two rollers. The first roller contacts an outer surface of the first double cam and the second roller contacts an outside surface of the second double cam.

Abstract: A main cam of a buttonhole sewing machine has four cams connected together in an assembly which includes a drive disk switch spring. A worm hub and a drive disk are connected together. A shifter mechanism has right and left shifter arms and springs which periodically capture and release the drive disk switch spring. The drive disk and worm hub are driven by a worm gear on the main drive shaft. One of the shifter arms holds the switch spring in a detent, disengaging the switch spring from the drive disk while the buttonhole sewing machine sews bight stitches along a first side of the buttonhole site in a workpiece. The workpiece is clamped between a clamping plate and a clamp. The clamping plate moves in steps while the needle is up. When the clamping plate reaches the end of the intended buttonhole a shift plate is moved, moving the shift arms, releasing the switch spring from the first switch arm and positioning the second switch arm for capturing the switch spring.

Abstract: A buttonhole sewing machine drive motor is turned on with an on switch. A large foot pedal engages the drive pulley on the motor and drives a V-belt. The V-belt drives a pulley and a timing pulley, which in turn drives a timing belt. The timing belt drives a clutch timing pulley, which freely rotates around a main drive shaft of the buttonhole sewing machine. When a small foot pedal is pressed downward, an air-activated over-the-center toggle connection moves a slide bar which moves a clutch switch spring. Parallel extension on the clutch switch spring move thrust washers and an interposed thrust bearing. The thrust washers compress a clutch disc assembly which engages the clutch timing pulley. A switch bushing is locked to the clutch disc assembly, and brake springs in a hand wheel assembly are locked to the switch bushing. The brake springs engage a hand wheel disc which is connected to a hand wheel and which is connected to an end of the main drive shaft for turning the drive shaft.

Abstract: A grooved barrel cam is mounted on a needle bar drive shaft. As the last step, after stitching is completed and power is removed, an engaging arm inserts a follower pin into the cam. A knife cam follower lever drives a knife drive shaft and a knife driving lever. The knife driving lever drives a knife holder downward. A connector at a middle of the knife holder maintains the holder vertical. A knife is secured at the bottom of the knife holder. The cam and a tension spring angularly return the cam follower lever, the shaft and the knife lever and lift the holder, when the cut has been completed. A compression spring around the knife drive shaft moves the follower away from the cam once the engaging arm has released the follower. Engaging the knife cam follower and operating the knife driving mechanism on the last revolution after the clutch is released helps exhaust the kinetic energy of the sewing machine before bringing the machine to a stop.

Abstract: A feed mechanism for a buttonhole sewing machine has a movable plate with a clamped piece of cloth. A rack is formed on a rearward extension of the plate. A pinion engages the rack, and a large gear is fixed to the pinion. An upper driving gear drives the large gear and is fixed to a vertical stub shaft which extends through the base of the sewing machine. A lower driving gear is mounted on the lower end of the vertical stub shaft beneath the work-supporting surface. A longitudinally shiftable horizontal shaft is mounted beneath the vertical stub shaft. A left bevel gear and a right bevel gear are keyed to the shiftable shaft. The shaft may be shifted so that either one or the other bevel gear engages the gear on the vertical stub shaft, or to an intermediate position in which the bevel gears are disengaged. The horizontal shaft is driven by a ratchet mechanism.