Shuttle Cover The shuttle cover slides sideways to reveal the Bobbin Case. The cover should always be closed when operating the machine (Photo 28).
Table and Lubrication A sewing machine head needs ample lubrication at various points. Most lubrication is done via a light oil to areas having felt wicks that retain the oil and dispense it slowly to the moving parts. Photos 29 & 30 show red marked points where this Juki machine should be oiled per the manufacturer's instructions. Other oil reservoirs may be included in your particular machine. Be sure to check the manual carefully. Ample lubrication is necessary, just exercise care in not over oiling the machine. Too much oil fly off the machine and get into your upholstery project and possibly staining it permanently.
Photo 29 This JUKI machine includes red marks at select holes to aid in lubricating your machine. Use the recommended oil and use what is required. Too much oil can splatter onto your work. Refer to your owner's manual for specific lubrication information.
Photo 30 Additional lubrication points are shown. This cover can be removed for lubrication and inspection.
Thread Thread available from the upholstery industry comes in different compositions, colors and sizes (Photo 31). Composition can be Nylon or Bonded Nylon, Cotton and Polyester. There are different terminologies for thread size: V, (T) and Ticket. This Thread and Needle Chart from Toledo Industrial Sewing machines provides a good reference. V69 and V92 are commonly used for stitching seams together and the larger thread sizes can be used for top stitching, an application where a thick thread is desired to make a stronger stitch appearance such as on a door panel. Superior Threads offers a Thread Guide that shows thread sizes.
Photo 31 Various colors of thread are shown in cones. The large cone of white is a nylon where as the small ones are poly cotton blend. Unique colors are usually offered in smaller cones.
Needles and Bobbins You will need an assortment of needles and bobbins for your projects. Most are sold in small packages of 12 or a full box of 100. Same goes for bobbins. Purchase a few dozen and have them on hand. You will want to wind several bobbins of each color required for your project. You may not use them all immediately, but you don't want to have to interrupt your sewing in the middle of a project to wind a bobbin. (Photo 32).
Photo 32 A sample of bobbins and needles. Needles come in a variety of sizes and point styles.
Stitch Tension The tension of a seam's stitches is important. If the top tension is too tight, the thread from the bobbin will get pulled up to the top of the hole and will been seen. Conversely, if the top tension is not tight enough the bobbin's thread will be too tight and pull the top thread down. The perfect stitch is one where the top tension is matched against the bobbin's tension and the loop that is created is in the middle of the layers of material (Photo 33). This is especially important for two reasons. If the tension is low on either side the seam may pull apart, weaken or even break. Or, if different color threads are used for each side of the material, you don't want the different color thread from the back side showing up on the front side. For more on bobbin and machine thread tension adjustments, visit Superior Thread's education section on adjusting bobbin tension and machine thread tension adjustments.
Photo 33 Graphic showing the importance of stitch tension. Too much tension on top can pull the bottom thread too high (top of graphic) and like wise too little can cause the junction of the top and bottom threads to be at the bottom. Correct tension is where the junction of the two threads is in the middle (middle of graphic).
Lock Stitch A lock stitch is usually a series of three stitches that are forward stitched, then reversed and again forward stitched. This is done using the Reversing Lever and for beginners, rotating the hand wheel. Once you get experience, it's possible to use the treadle and motor to do lock stitches and it goes pretty quickly once you get accustomed to the machine's operation.