4 - Basic Knowledge Series for lockstitch machines - Basic k

It does not provide adequate efficiency of feed on multi-layered parts of the material, resulting in undesired stitch gathering. • When putting in a heavy-weight material, such as a multi-layered part, from the right side of the feed dog, efficiency of feed is inadequate when starting sewing. In this case, undesired stitch gathering can result.

[Features of the feed dog with four rows of teeth] This type of feed dog provides increased efficiency of feed since it has teeth on the near side of the needle entry. Therefore, the feed dog smoothly feeds a multi-layered part of material and securely catches the material at the start of sewing. (Fig. 10)

This type of feed dog does not smoothly feed the material at sharp curves.

• In particular, the feed dog is suited for sewing long materials which require smooth feeding of multi-layered parts at the start of sewing and a straight-feeding capability. • In general, the troubles described below are likely to occur according to the "teeth" configuration of the feed dog. • When the feed dog teeth are as sharp as a blade: The teeth can be a cause of damaged materials, broken sewing-thread and broken chain-off thread. • When the teeth surfaces are not level, the material may not be fed straight. (The material may skew to the right or left.)

In this case, slightly abrade the tooth surfaces with an oilstone or the like for correction. If the teeth have been significantly deformed and cannot be corrected, replacement of the feed dog is recommended.

5. Height and inclination of the feed dog

(1) Height of the feed dog The feed dog height can be adjusted in the range of 0.5 mm to 1.2 mm according to the sewing material. Standard heights of the feed dog are as follows:

For light-weight materials -> 0.5 mm to 0.6 mm For medium-weight materials -> 0.7 mm to 0.8 mm For heavy-weight materials -> 0.9 mm to 1.2 mm

When the height of the feed dog is too high: Efficiency of feed is adequate, but puckering is likely to occur.

When the height of the feed dog is too low: Efficiency of feed is inadequate, but puckering is not likely to occur.

Basic Knowledge Series for Lockstitch Machines | © 2018 Superior Sewing Machine & Supply LLC