Standard spindle taper used on drilling machines The drill spindles on conventional drilling machines are commonly provided with which standard taper?

Introduction / Context:
Tapers allow self-holding, accurate alignment, and quick tool changes in machine tools. Drilling machines around the world largely standardize on a particular taper for compatibility of spindles, sleeves, and drill shanks.

Given Data / Assumptions:

• General-purpose pillar, radial, and bench drills.
• Self-holding taper fits without drawbar for typical sizes.

Concept / Approach:
The Morse taper series (MT1–MT7) is the de facto standard for drill spindles and shanks due to its self-holding characteristic, ease of ejection with drift slots, and broad availability. Other tapers exist in machine-tool practice but are not the predominant standard for drill spindles.

Step-by-Step Solution:
Identify common practice: drills and sleeves marked MT numbers.Confirm self-holding design suits drilling thrust loads.Select “Morse taper” as the standard.

Verification / Alternative check:
Tooling catalogs, drill sleeves, and spindle specifications consistently reference Morse tapers.

Why Other Options Are Wrong:
Seller’s, Chapman, Brown & Sharpe, and Jarno tapers exist but are less common for drill spindles in modern general-purpose drilling equipment.

Common Pitfalls:
Confusing milling spindle tapers (e.g., CAT/BT, R8) with drilling tapers; mixing Morse taper numbers with taper-per-foot specifications of other standards.

Final Answer:
Morse taper