Thread Cutting Part 1: Cutting an internal thread

Stage 1: Marking Out a) Accurately mark out the position for the threaded hole. b) Centre punch the position for the hole

Stage 2: Drilling c) Carefully drill the hole. a) Choose the appropriate drill size from inside the box of taps b) Find the closest drill size in the box

Stage 3: Choosing the correct Tap Taper Tap Second Tap Plug Tap Each size of Tap is available in 3 types: Taper, Second and Plug. To start with choose the Taper plug and fit it into the Tap Wrench. Tap Wrench Taps are made from High Speed Steel (HSS)

The Taper Tap has a tapered lead in which extends over the first eight or nine teeth of the cutter which makes it easier to start the thread The Second Tap has a slight taper (over the first three or four teeth) The Plug Tap is for finishing the thread and has no tapered teeth (only a slight chamfer at the start to provide a lead in) Taps

Stage 4: Taper Tap Cutting a) Fix your work piece securely in the vice. c) Holding the Tap Wrench as horizontal as possible start turning the tap in a clock wise direction. b) Apply a small amount of cutting compound to the tap d) Once the tap starts cutting solid resistance to the cutting action will be felt. At this point the tap should be turned back about ½ a turn to break off the swarf. This process should be repeated until the taper tap has passed through the metal. Cut ThreadBreak Swarf

Stage 4 Taper Tap Cutting e) Once the taper tap has passed through the bar it should be withdrawn, cleaned and returned to the box

Stage 5 Second Tap Cutting a) Fit the Second Tap into the tap wrench, apply cutting compound and re-cut the thread.

Stage 6 Plug Tap Cutting a) Fit the Plug Tap into the tap wrench, apply cutting compound and re-cut the thread. (the plug tap should be easy to turn)

Stage 7 Testing Test the thread with an appropriate sized Bolt

The End