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sewing machine 
Machine used to assemble two pieces of fabric by means of a series of stitches made with a needle and thread.
tension block 
Parts that control the tension of the upper thread.
thread guide 
Part that leads the thread toward the tension disk.
tension disk 
Each of the parts between which the thread passes during threading.
tension dial 
Graduated dial used to regulate the tension of the upper thread.
tension spring 
Spring that keeps the upper thread between the tension disks.