Editing Tap and die (section)

== Die ==
[[Image:ThreadingDies.jpg|thumb|Five die sizes and types]]

A ''die'' cuts an external thread on [[cylinder|cylindrical]] material, such as a rod, which creates a male threaded piece that functions like a [[Screw#Differentiation between bolt and screw|bolt]]. Dies are generally made in two styles: solid and adjustable.
An adjustable die may be adjusted either by an integrated screw or by a set of screws set in to the die holder (termed a "die stock"). 
Integral adjusting screws may be arranged to work axially, where the movement of the adjusting screw into a threaded hole in the die forces the slit section of the die open, or tangentially where a screw threaded in to one side of the slit bears against the opposite side of the slit. 
Dies without integrated screws are adjusted inside the die stock by radially-arranged screws. Two screws in the stock bear in to indentations on either side of the slit, tending to squeeze the slit closed, whilst a third screw with a tapered tip screws in to the slit forcing it open. Working these three screws against each other adjusts the die. 

Integrated screws appear to be common in the US but are almost unknown in the UK and Europe. 

The dies shown in the image to the right are adjustable:
* top left:  an older split die, with top adjusting screw
* bottom left:  a one piece die with top adjusting screw
* center:  a one piece die with side adjusting screw (barely visible on the full image)
* right:  two dies without integrated adjusting screws

Solid dies cut a nominal thread form and depth, whose accuracy is subject to the precision the die was made with, and the effects of wear.  Adjustable dies can be slightly compressed or expanded to provide some compensation for wear, or to achieve different classes of thread fit (class A, B and more rarely, C). Adjustable taps also exist but are not common. These have a tip that is split through the flutes and an axial screw which forces the cutting edges slightly apart. 

The work piece (blank) to be threaded, which is usually slightly smaller in diameter than the die's major diameter, is given a slight taper (chamfer) at the end that is to be threaded. This chamfer helps center the die on the blank and reduces the force required to start the thread cutting.<ref>
{{cite web
 |url         = http://www.tapdie.com/html/taps_dies_terminology.html
 |title       = Taps and Dies Terminology
 |publisher   = TapDie.com
 |access-date  = 2006-12-03
 |url-status     = usurped
 |archive-url  = https://web.archive.org/web/20061119001822/http://www.tapdie.com/html/taps_dies_terminology.html
 |archive-date = 2006-11-19
}}</ref>  Once the die has started, it self-feeds. Periodic reversal of the die is often required to break the chip and prevent crowding.

''{{visible anchor|Die nut}}s'', also known as ''rethreading dies'', are dies made for cleaning up damaged threads,<ref>{{cite web|url=http://www.tpub.com/content/construction/14256/css/14256_231.htm|title=Types and Uses - Continued - 14256_231|website=www.tpub.com|access-date=7 May 2018|url-status=live|archive-url=https://web.archive.org/web/20090309154922/http://www.tpub.com/content/construction/14256/css/14256_231.htm|archive-date=9 March 2009}}</ref> have no split for resizing and are made from a hexagonal bar so that a [[wrench]] may be used to turn them.  The process of repairing damaged threads is referred to as "chasing."  Rethreading dies cannot be used to cut new threads as they lack chip forming teeth.<ref>{{cite book | last = Keenan | first = Julian Paul | title = ASVAB - The Best Test Prep | publisher = Research & Education Association | year = 2005 | isbn = 978-0-7386-0063-5 }}</ref> However the external profile of a die does not strictly map to its function. Manufacturers of dies have produced models in a hex form which are intended for the creation of new threads.<ref>{{Cite web |title=High Carbon Steel 38 Piece Do-it-yourselfer Tap & Die Set |url=https://vermontamerican.com/products/high-carbon-steel-38-piece-yourselfer-tap-die-set/ |access-date=2022-07-02 |website=Vermont American |language=en-US}}</ref> These appear identical to solid dies in all aspects besides the external shape. Hexagonal thread cutting dies are used with a die stock with hexagonal holding features.