Nota BCP

PLUG

• A plug tap is tapered for approximately
three thread.

• Sometimes the plug tap is the only tap
used to thread a hole going through a
workpiece.

BOTTOMING

• A bottoming tap is not tapered but
chamfered at the end for one thread.

• It is used for threading to the bottom of a
blink hole.

• When tapping a blink hole, first the taper
tap, then the plug tap, and complete the
hole with a bottoming tap.

Tapping workpiece process

• STEP 1 > Drilling
• STEP 2 > Countersinking
• STEP 3 > Taper
• STEP 4 > Plug
• STEP 5 > Bottom

Tap Wrench

 Tap Wrenches have adjustable jaws that permit the use
of a variety of tap sizes (from 1" down to 1/16" diameter.

 The tap wrench is often used where there is limited
space between the spindle and the work piece

DIES

• Threading dies are used to cut external threads on round work. The most
common threading dies are the solid, adjustable split, and the adjustable
and removable screw plate die.

• The solid die is used for chasing or recutting damaged threads and may be
driven by a suitable wrench. It is not adjustable.

• The adjustable split die has an adjusting screw that permits an adjustment
over or under the standard depth of thread. This type of die fits into a die
stock.

TAP DRILL SIZE

• Before a tap is used, the hole must be drilled to the correct tap drill
size. This is the drill size.

>simple formula:
TDS = D – 1/N
Where TDS = tap drill size
D= major diameter of tap
N= number of thread per inch