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Specifies a method of test for determining the variation of needle thread tension at given positions of the tension regulator. The method is applicable to motor-operated household sewing machines, but it may also be possible to apply it to hand- or treadle-operated machines. Includes additionally to principle, material and apparatus, procedure, expression of results and test report an annex which specifies the cotton thread.
||Household sewing machines - Determination of stability of needle thread tension