| Solid Carbide Thread Mills TOSCO Solid Carbide Thread Mills are manufactured with rigid specifications
  for both dimensional and material integrity. The highest quality micro grain
  HIP tungsten carbide material is ground to exacting tolerances established by
  the TOSCO engineers. This results in tools which have maximum strength,
  long life and unsurpassed repeatability. Solid Carbide Thread Milling Cutters
  are stocked with TiALN coating. Uncoated tools or
  other coatings are available upon request. Either full form or stagger tooth
  designs are available, with options of straight or spiral flute. All TOSCO tools
  can be easily sharpened between centers by the user or returned to TOSCO for
  resharpening or refurbishing. Class of thread
 
A classification system exists for ease of manufacture and interchangeability of fabricated threaded items.
Most (but certainly not all) threaded items are made to a classification standard called the Unified Screw
Thread Standard Series. This system is analogous to the fits used with assembled parts.
 
Classes 1A, 2A, 3A apply to external threads; Classes 1B, 2B, 3B apply to internal threads.
 
Class 1 threads are loosely fitting threads intended for ease of assembly or use in a dirty environment.
 
Class 2 threads are the most common. They are designed to maximize strength considering typical machine shop capability and machine practice.
 
Class 3 threads are used for closer tolerances.
 
For more information see: http://en.wikipedia.org/wiki/Unified_Thread_Standard
           |