Computer-controlled, High-speed, Lockstitch Buttonholing Machine LBH-1790 The machine offers increased flexibility. It achieves the highest productivity and seam quality. The machine eliminates oil stains on the sewing product. Thanks to our advanced dry-head technology, no lubrication is required except for the hook section. This eliminates oil stains on the sewing product.     The machine can be completely changed into a dry-head machine by replacing the hook with an optional non-lubricated hook. (In this case, the maximum sewing speed will be 3,300rpm.) Only a minute-quantity of clean oil is fed to the hook section from the oil tank. JUKI's unique active-tension (Electronic thread-tension-control system). Needle thread tension for sewing parallel and bartacking sections of buttonholes can be separately controlled through the operation panel and stored in memory according to various sewing conditions (e.g., type of thread, type of material and sewing speed).     The machine is able to change the needle thread tensions at the parallel and bartacking sections of the buttonhole, to produce a beautiful buttonhole shape. This capability helps greatly in preventing thread breakage.     Needle thread tension is activated at the beginning and end of sewing. This prevents unthreading of the needle thread, and thread fraying that is likely to occur at the beginning of sewing.     Thread tension for basting stitching can be specified separately. Frame shape offers improved operability. The hollowed type frame promises efficient sewing of vertical buttonholes. The machine can be operated with its head positioned horizontally.     The distance from the machine arm to the needle has been lengthened and the left side section of the needle entry has been reduced by a large margin. This helps in the smooth placement of the sewing product on the machine, thereby ensuring improved workability. The sewing product can further be placed on the machine easily by installing the auxiliary table (standard accessory). In addition, the needle entry is located in the center of the bed, promising easier positioning of the sewing product.       Basting stitch mechanism is effective for the production of beautiful buttonholes. The basting stitch is effective on elastic materials such as knits. Two different stitching styles are possible, i.e., “basting stitch” and “joining stitch.” These two styles of stitches may also be combined. (Sewing is carried out in the order of joining stitch, basting stitch and regular stitch.) Basting stitch: Since the needle thread is tucked in without fail, it will never jut out of the buttonhole seams. Basting stitch can be sewn by nine rounds. Joining stitch: It works to prevent the buttonhole from expanding, thereby helping to finish beautiful buttonholes. Without basting stitch With basting stitch Basting stitch Joining stitch (The state in which the material is stretched in the lengthwise direction after buttonholing)       Sewing settings can be easily changed.   Purl stitching   Whip stitching   State of first-round stitch   Finished state of double stitching (For a changeover between purl stitch and whip stitch, threading of bobbin, as well as the bobbin thread tension need to be changed.)   • For double stitching, the bartacking section is skipped and only the parallel sections are sewn twice. This prevents any excessively tight finishes in the bartacking section of the buttonhole. • First- and second-round stitches can be sewn using different stitch widths.         Shorter length of bobbin thread remaining on the material. The new model of the bobbin thread trimming mechanism cuts the bobbin thread so that it leaves a shorter length of thread on the material. Furthermore, the machine produces bartacks at the end of sewing, thereby preventing finished seams from coming undone.     With the soft-start function, the number of stitches, as well as the sewing speed at the start of sewing can be specified, thereby preventing the needle thread from slipping off from the needle eyelet. (From the first to the fifth stitches, the sewing speed can be specified on a stitch-by-stitch basis.)       The machine is equipped with a multiple knife-dropping function. Thanks to the multiple knife-dropping function, it is no longer required that the knife be changed at the time the buttonhole size is changed. The number of knife dropping times can be automatically set according to the buttonholing size in cases where the buttonhole size is frequently changed for small-lot productions or during the cycle sewing of buttonholes that are different in size.     The double-acting solenoid type knife mechanism is free from the faulty dropping/returning of the knife. In addition, the knife pressure can be changed according to the material to be sewn.     The knife supports sewing lengths of 41mm at the maximum. In addition, knife mechanisms for 70mm and 120mm are optionally available. With this, slots such as the belt holes of child seat belts can be buttonholed.         Cycle sewing and continuous sewing. Cycle sewing Twenty different programs can be registered, and as many as 15 different patterns can be stored in one program. Continuous sewing The machine is able to continuously sew two or more different patterns without requiring the work clamp foot to be lifted. As may as 20 programs can be registered, and six different patterns can be stored in one program. (Related parts need to be exchanged for optional ones.) Easy threading. The needle bar can be shifted to the rightmost end position with the work clamp foot lowered. This facilitates threading of the machine head.       Position of the needle bar during sewing   The needle bar can be shifted to the right at the time of threading Many functions of the pedal. The machine is provided as standard with a newly-developed auto-lifter driven by a stepping motor. This helps reduce the operator's fatigue. This helps reduce operator fatigue. As for the pedal, one-pedal and two-pedal models can both be changed over and the intermediate stop, which facilitates positioning of the sewing product, can be specified. The work clamp foot lift can be set as desired. The reverse-rotation needle-up function offers a maximum work clamp foot lift of 17mm. Explanation of pedal motion Pedal motion Pedal type 2-pedal 1-pedal (without intermediate position) 1-pedal (with intermediate position) Initial position Intermediate position Maximum position Maximum position Setting of sewing product Presser goes up as high as the pedal toe down amount of the left side pedal. Presser comes down when the left side pedal is depressed. Sewing position The first step of the right side pedal Sewing position The first step of the right side pedal Intermediate position The second step of the right side pedal Sewing position Start of sewing The right side pedal is depressed. The second step of the right side pedal The third step of the right side pedal End of sewing Presser automatically goes up to intermediate position. Presser automatically goes up to maximum position. Presser automatically goes up to maximum position. Major drive mechanism is electronically controlled. An electronic control feature has been adopted for the material feed mechanism, needle rocking mechanism, needle thread trimming mechanism, bobbin thread trimming mechanism, cloth cutting knife mechanism and presser bar lifting mechanism. In addition, mechanisms such as V-belts, stop-motion mechanisms and cams have been substantially reduced to ensure operation with lower vibration and noise.     A direct-driven system that directly connects the compact AC servomotor to the main shaft has been adopted.     All adjustment values are entered as data. They can be set or stored in the memory on the operation panel.