THSG - BA Taps
In stock
SKU
THSGBA
M2 High Speed Steel Precision ground thread Class 2 ISO R.529 BS949 Pt 2
Parallel shank with square Straight Flute Right hand threading
Full form with Taper, Second, or Bottoming lead for BA ‘Thury’ threads to BS 93
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
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. Other serial form taps
may be supplied, but only to special order].
British Assocation thread were designed in 19th century using a derivation of metric dimensions
where 0BA = 6mm x 1mm pitch [0.236” x 25,4 TPI] and each succeeding number represented 90% of the preceding.
It is no longer a mainstream thread system but is still used widely in legacy electronics and instrument work, and a
few other industries. It should be noted that no size, even 0BA, is interchangeable with the present metric system as
the thread profile, based on a Swiss design, is very different.