M2 High Speed Steel Precision ground thread Class 2B ISO R.529 BS949 Pt 2 Parallel shank with square Straight Flute Right hand threading Full form with Taper, Second, or Bottoming lead for UNC threads to ANSI B1.1 Usually supplied in bright ground finish Tap basic dimensions shown in mm May be used by hand or in machines to produce accurate threads in most materials
*IMPORTANT. Length of thread is indicative only and can vary between manufacturers within normal practice. It is not necessary to have a long thread length because of the thread length that is required to be made - in recent years shorter thread lengths are being recommended increasingly, especially when for machine operations. ISO R.529 sets a maximum threaded length, but not a minimum. **Some stocks of sizes above 1,3/4” have four flutes, and these may be supplied when available. Taps may be supplied with coatings such as TiN (Titanium nitride) to special order, the quantity ordered determining the unit price. Taps to special tolerance classes (i.e. other than 2B) may be supplied to special order, the quantity determining the unit price. oversize taps (for making threads which are to be subsequently plated, or for insert repair) may also be ordered, and are subject to quantity scales as above. Please be sure to specify the exact oversize required, or the insert repair system used. Sets of Taps A set of three hand taps in this series will consist of taps with taper, second, and bottoming leads. They are full form, and so differ only in the length of the chamfered lead provided, so it may not always be necessary to use a full sequence of three taps to make the finished thread [compare this with serial form taps -shown here (in metric size) under DIN352. Unified serial form taps may be supplied, but only to special order]. # Unified number sizes. Nominal “inch” sizes for unified screw threads below 1/4” major diameter are no longer recognised — since the introduction of the unified system in 1949. The major diameter in inches of the number sizes now used is given for reference below. Requests for UNC or UNF diameters below 1/4” , but expressed as inches (which have never officially existed) may occasionally still be met. “1/8” UNC and UNF can be supplied as #5, but other diameters have no exact equivalent and would be completely special.
