Can't find what you are looking for ? - then please let us know by e mail  or give us a call and we'll do our best to help

Tapping Terminology

Home Up Tapping Terminology Tapping Guide Metric Taps BA Taps Metric Dies Drill Bits UNC Taps BA Dies Glow Plug Taps UNF Taps UNC & UNF Dies BSW Taps BSF Taps BSW & BSF Dies Trend Snappy

New Feature!


Please click here for
further information



Below we have attempted to briefly explain the tools and their use plus some other terminology used in the process of hand tapping of threads.

Blind Hole   A hole drilled into a material from one side without penetrating the opposite side.
Tap hole diameter  

This is the diameter of the hole that should be drilled prior to tapping the female thread

Taper Tap

This is the initial tap used to start the tapping process for a female thread. They have a long lead in of 7 to 10 threads.  Also often referred to as '1st Tap'. For softer materials it is often possible to go straight to a second tap.

Second Tap

As the name suggests, this is used after the taper tap to produce the full thread in 'through holes' or 'blind' holes where the thread does not need to go close to the bottom of the hole. Sometimes referred to as 'intermediate taps'

Bottom Tap

Used where the thread is required to extend near to the bottom of a blind hole. Often termed a 'plug' tap in the UK. Note that the tips of the smaller sized bottom taps are pointed. Larger taps for thread sizes of M8 & 5/16" and larger have a flat end. 

Split Dies Dies are used to cut male threads - i.e. as on a screw. The most common form are split dies which enable some adjustment of the diameter for increased accuracy and to compensate when the die eventually wears.
Tap Wrench / Handle

A tool for holding the tap during the hand tapping process. We offer the option of a 'Tee Handle' style (left) ideal for the smaller sizes, and the traditional adjustable tap wrench type (below).

Adjustable Tap Wrench

A tool for holding the tap during the hand tapping process. The more traditional style with a larger range capacity of tap sizes. Gives better control of the larger sizes.

Die Holder

A tool for holding the die during the thread cutting process


This page was last modified on : September 27, 2020

Send mail to with questions or comments about this web site.
General & Sales Information:

All Trademarks and Trade names acknowledged.

Privacy Policy

Model Fixings Ltd trading as,,

Registered in England and Wales, Company No 8887251. Vat No GB917415524

Modelfixings is registered and fully compliant with PCI DSS (Payment Card Industry Data Security Standard) requirements