Mechanical adjustment-
Adjustment of the Synchronization
机针与送布时间的同步调整：（
needle plate
、
top of the feed dog
、
Pinhole bottom flush
）
To get the synchronous
adjustment of needle and the feed dog, easy breakage when feed dog is too slow, back stitch is more obvious. When
the feed dog is too quickly, the thread is not tight, especially when using a thick thread is more obvious.
