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A sewing machine is a machine used to stitch fabric and other materials together with thread. [1] Sewing machines were invented during the first Industrial Revolution to decrease the amount of manual sewing work performed in clothing companies. [2]
An additional looper above the material can form a top cover stitch simultaneously. The needle threads form parallel rows, while the looper threads cross back and forth all the needle rows. Coverstitch is so-called because the grid of crossing needle and looper threads covers raw seam edges, much as the overlock stitch does.
The major minus pitch technique also works for inch-based threads, but you must first calculate the pitch by converting the fraction of threads-per-inch (TPI) into a decimal. For example, a screw with a pitch of 1/20 in (20 threads per inch) has a pitch of 0.050 in and a 1 ⁄ 13 in pitch (13 threads per inch) has a pitch of 0.077 in.
The Unified Thread Standard (UTS) defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada. It is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in these countries.
Unified Miniature Screw Threads: V Thread Form: 0.60 UNM ANSI/ASME B1.11-1958 (R2016) Microscope Objective Thread: V Thread Form ASME B1.13M-2005 (R2015) Metric Screw Threads: M Profile: V Thread Form ASME B1.15-1995 (R2003) Unified Inch Screw Threads (UNJ Thread Form) V Thread Form ASME B1.20.1-2013: Pipe Threads, General Purpose (Inch) Pipe ...
Both tools can be used to clean up a thread, which is called chasing. However, using an ordinary tap or die to clean threads generally removes some material, which results in looser, weaker threads. Because of this, machinists generally clean threads with special taps and dies—called chasers—made for that purpose. Chasers are made of softer ...
A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by a dash or sometimes the multiplication sign, × (e.g. M8-1.25 or M8×1.25). If the pitch is the normally used "coarse" pitch listed in ISO 261 or ...
This thread form also allows for the use of a split nut, which can compensate for nut wear. [8] The line of General Purpose (GP) Acme threads (ASME/ANSI B1.5-1997) are not designed to sustain external radial loads and both the nut and bolt are, ideally, independently supported (the nut by a linear guide and the screw by shaft bearings).