Are a Plug Tap and a Bottom Tap the Same?
No, a plug tap and a bottom tap are not the same, although they are both types of taps used in machining and threading processes. They differ significantly in their design, application, and the type of threads they create. Understanding these differences is crucial for selecting the right tap for a specific job and ensuring accurate, efficient thread creation.
What is a Plug Tap?
A plug tap is a type of tap with a relatively short, tapered cutting section. This taper allows it to easily start the threading process, even in slightly misaligned holes. The flutes (grooves) on a plug tap are designed to carry away chips effectively, making it suitable for through-hole threading where chips can readily escape. Plug taps are typically used as the second tap in a sequence of three (taper, plug, bottoming). They are not intended for creating full threads all the way to the bottom of a blind hole.
What is a Bottom Tap?
A bottom tap, also known as a bottoming tap, has a very short cutting section with almost no taper. This allows it to create complete threads all the way to the bottom of a blind hole (a hole that doesn't go all the way through the workpiece). The minimal taper means it requires precise alignment to start the threading process. Because of its design and the difficulty of chip evacuation, bottoming taps are more prone to breakage than other types of taps. They are generally used as a final tap to ensure the full depth of the thread is cut.
What are the Key Differences Between Plug and Bottom Taps?
The table below summarizes the key differences:
| Feature | Plug Tap | Bottom Tap |
|---|---|---|
| Taper | Significant taper | Minimal or no taper |
| Cutting Section | Relatively long | Very short |
| Application | Through holes, second tap in a set | Blind holes, final tap in a set |
| Chip Removal | Good chip evacuation | Poor chip evacuation; prone to clogging |
| Starting | Easier to start, even misaligned holes | Requires precise alignment |
| Thread Depth | Does not cut full threads to the bottom | Cuts full threads to the bottom |
| Breaking | Less prone to breakage | More prone to breakage |
What Happens if I Use the Wrong Tap?
Using a plug tap in a blind hole could result in incomplete threads, while using a bottom tap in a through hole might lead to the tap breaking or binding. Always select the correct tap type based on the type of hole (through or blind) and the desired thread depth.
What are the different types of taps available?
Beyond plug and bottoming taps, there are also taper taps, which have a long taper and are used as the first tap in a multi-tap sequence to start the thread and make initial cuts. The choice of which tap to use often depends on the material being tapped and the desired thread quality.
Using the correct tap is essential for creating accurate, clean threads. Understanding the differences between plug and bottoming taps will ensure you select the right tool for the job and avoid potential damage or frustration.
