Tapping blind holes Which tap is specifically used to cut threads to the full depth in a blind hole (minimal chamfer length)?

Introduction / Context:
Tapping sets commonly include three taps: taper, second (plug/intermediate), and bottoming. Understanding the chamfer length and application ensures full thread depth in through and blind holes without damaging the tap or the workpiece.

Given Data / Assumptions:

• Blind hole with limited depth.
• Need to produce full thread depth near the hole bottom.
• Standard hand taps with progressive chamfer lengths.

Concept / Approach:
The taper tap has the longest chamfer and is easiest to start but cannot reach near the bottom. The second tap has a moderate chamfer and deepens the thread. The bottoming tap has 1–2 lead threads, allowing the full thread profile to be formed close to the bottom of a blind hole.

Step-by-Step Solution:

Verification / Alternative check:
Manufacturer data sheets specify lead threads and intended use; bottoming taps are explicitly indicated for blind holes.

Why Other Options Are Wrong:
Taper/second taps cannot produce full depth near the bottom due to longer chamfer.“Any one of these” is incorrect because only the bottoming tap reaches near the bottom.Pipe taps are specialized for tapered pipe threads, not general metric/UN blind holes.

Common Pitfalls:
Attempting to use only a bottoming tap to start may cause misalignment or breakage; proceed progressively or use machine tapping with proper guides.

Final Answer:

Bottoming tap