Introduction: How to Tap Screw and Bolt Threads
A very useful tool and skill to have is tapping screw and bolt threads. Tapping is a process of cutting threads into a hole so it can accept a bolt or screw called threading. With a little bit of practice it is a very simple and easy process provided you take your time. Also taps can be used to repair threads in bad condition.
Taps can be bought individually or you can buy a tap and die kit that will include a variety of sizes. Tap and die kits come with both taps and dies and is your best value. This Instructable covers tapping but dies are similar in that they are used to add threads to a rod instead of a hole, thereby making a "bolt". Whereas tapping/threading makes the "nut"
You will need the following:
- Tap and Wrench or Tap and Die set.
- Drill bits
- Lubricating or Cutting Oil (almost any lubricate will work, just use something)
- Material that will be tapped
Step 1: Tap Used
There are different types of taps. The one used in this Instructable is a tapered tap. A tapered tap is easier to start and is used for materials that are hard to cut or if the hole to be tapped is small.
Step 2: Video of Tapping a Hole
Here is a video on the whole process. The written steps follow.
Step 3: Drill Hole in Material for Tapping
The tap you will be using will need a corresponding drill bit to drill a hole in the material you want to tap. The tap will come with instructions that tells you what drill bit size to use. It will be smaller than the tap size so the tap will have material to cut into to make the threads.
Step 4: Tapping the Hole
Put the tap in the handle or wrench and add some lubricating/cutting oil to the tap. The oil will help the tap cut into the material and makes removing the cut material (chips) easier. The lubrication also prolongs the life of the tap. Turn clockwise until you feel the tap cutting into the material, don't over turn if the tap does not cut with ease. You will need to back out the tap to clear the chips every feel turns. I usually do one or two turns and then back out a turn or two. Once you start you will get a feeling for it. Repeat until the depth of threads is reached and the tap threads in and out easily. Wipe clean the oil and chips or blow out any stuck chips with air.
Step 5: Test With a Bolt With the Correct Threads.
Make sure the threads are clean, blow out with air if necessary. Try your bolt in your freshly cut threads. If it binds run the tap through the threads to clean them up.