Where to use each Type of Thread Taps
Posted: December 10, 2018 By: MattM
It’s inevitable you’ll come across an instance where you’ll need to tap or repair threads on a project. Threaded fasteners hold just about everything you in your life including the car you drive. When tapping or repairing threads there are 4 common hand taps and they each have a specific use. Eastwood Tap and Die Kits have just about every tap and die you would using in a home shop. Below we cover the most common types of taps and where you’d commonly use them.
- Bottoming Tap- A bottoming tap will be easily identified by the blunt end with only the first 1-2 threads tapered on the tap. This tap is used most commonly for tapping or correcting threads on a blind hole. In the automotive industry this tap is commonly used to safely tap holes in an engine where a pointed tap like a spiral or bull nose tap could actually puncture through the bottom of the hole and permanently damage an engine. The lack of taper on the bottom of the tap will allow the tap to fully thread to the depth of its reach. If you’re tapping a new hole we suggest to start with a taper tap and about halfway down switch to a bottoming tap to assure a full tap through the hole.
- Plug Tap- A plug tap or “second tap”has 3-5 tapered or chamfered threads on the end that help with starting a tapped hole. These work well for cleaning up threads on a hole that is already there. The first few tapered threads will help the tap get centered and clean up existing threaded holes. You can also use this tap after a spiral or taper tap has started the hole. Allow the taper tap to cut into the hole about 30-50% and follow with the plug tap. If you’re tapping a through hole you can use the plug tap to complete the hole; turning it completely through the hole past the tapered threads.
- Tapered Tap- Tapered taps are what you’ll most commonly find in a beginner tap kit. These have a steep chamfer on the end of the tap and the first 7-10 threads will be tapered. These are great for starting a new hole or a pre-existing tapped hole with there first 3-5 threads are damaged and another tap won’t catch. This tap can be used on through holes, but like a plug tap you should thread the tap past the tapered threads.
- Spiral Point “Bull Nose” Tap- This style of tap is one of the more common taps you’ll find in a basic tap kit. They have a heavy chamfer on the end and are designed to push the chips forward of the tap to ease the forced needed to tap a hole. These work well for through holes and cleaning up holes with damaged threads but should be avoided on a blind hole as you will miss up 8-10 or more threads and can damage the bottom of the hole.
If you want to get shop supplies for tapping holes for a DIY garage you can find them in our Tap and Die selection. This includes time-savers like ratcheting tap handles, and universal thread repair tools.