ASME B107.51-2001 — Star Drills: Safety Requirements

🪛 ASME B107.51-2001, an American National Standard published by the ASME B107 Committee, establishes safety requirements for the design, construction, testing, and use of hand-held star drills. A star drill is an ancient purely manual drilling tool: its working end carries a cross/star configuration of four cutting edges, and the operator drives it by repeatedly striking the top of the shank with a hammer while slowly rotating the body, so the impact chiseling of the edges drills a round hole in brick, tile, concrete, or stone. Before the spread of power rotary hammers it was the standard tool for making holes in masonry, and it remains valuable where no power is available, in confined spaces, and for accurately positioned auxiliary holes. The Standard was issued on February 28, 2001.

1. Scope and General Framework 📌

Section 1 (General) states that the Standard provides safety requirements for the design, construction, testing, and use of hand-held star drills intended for drilling holes in brick, tile, concrete, or stone. Key points:

• Only safety-relevant details are specified; manufacturing processes are not;
• It serves as a guide in selecting, testing, and using the tools covered;
• It supports the development of manuals, posters, and safe-practice training;
• It may be used by state authorities or other regulatory bodies and is intended for voluntary use by establishments that use or manufacture the tools.

Referenced documents include ANSI Z87.1 (occupational and educational eye and face protection, with supplement Z87.1a-1991), ANSI Z535.4 (product safety signs and labels), the ASTM bar and tool-steel specifications (A29/A29M, A322, A331, A576, A681), ASTM E18 (Rockwell hardness), and the HTI Guide to Hand Tools.

2. Construction and Nomenclature 🔧

Section 3 (Glossary), with the nomenclature figure (Fig. 1), defines the principal parts:

3. Materials, Mechanical Properties, and Tests 🧪

Section 4 (General Requirements) specifies:

• Materials: carbon and alloy steel bars, special-quality hot-wrought/cold-finished bars, alloy tool steels (ASTM A29/A29M, A322, A331, A576, A681);
• Mechanical properties: after heat treatment, edges and body must meet the specified Rockwell hardness range (per ASTM E18), with edges wear-resistant but not brittle and the body tough;
• Tests: specified impacts and loads are applied per the Standard’s methods to verify chiseling capability and body capacity;
• Acceptance: after testing, no cracks, chips, or permanent distortion affecting safe use may appear.

Because a star drill endures continuous high-frequency hammering and chiseling impact, the edge hardness/body toughness balance is even more critical than for ordinary chisels: too hard and edges shatter, too soft and they roll over quickly, collapsing drilling efficiency.

4. Safety Requirements and Limitations of Use 🛠️

• Eye protection: dust and fragments fly continuously; operators and bystanders must wear eye and face protection per ANSI Z87.1 (goggles and dust mask);
• Correct grip and rotation: hold the mid-to-rear of the body with one hand and rotate slowly, strike the shank top vertically with a suitable hammer; never place the hand in line with the cutting edges;
• Struck-face upkeep: grind back or discard a mushroomed struck face immediately to prevent flying fragments;
• Anti-slip start: begin with light blows and slow rotation so the tip does not skate on smooth surfaces;
• Stable work: pad and protect the surface around the hole to contain edge spalling at the hole mouth;
• Marking and training: safety signs per ANSI Z535.4 and training per this Standard.

5. Engineering Practice Essentials ⚙️

• Drilling sequence: locate with a center punch → open the hole with light blows → maintain a steady hammer cadence, rotating about 45° after each blow → withdraw periodically to clear chips;
• Rotation matching: rotate once every one or two blows; too little rotation redrills the same spot (slow), too much prevents the edges from gripping;
• Resharpening: regrind dull edges to the original star geometry on a grinding wheel, keeping all four edges equal, cooling thoroughly, and re-verifying hardness;
• Procurement acceptance: request hardness and test data from suppliers to confirm conformance with this Standard.

6. Frequently Asked Questions ❓