Machine guarding, grinders and portable tools

0:00 Intro

Machine guarding, grinders and portable tools, for the ASP exam. Every rule and number here is cited to its primary source, on screen.

0:10 Learning objectives

In this lesson, you'll learn to: state the machine guarding and point of operation rules, apply the fan blade and compressed air limits, know the grinder work rest and guard exposure numbers, and explain flange sizing and the ring test.

0:27 1910.212 · General machines

212, guarding must protect the operator and others in the machine area. Hazards include point of operation, nip points, rotating parts, and flying chips and sparks. Guards are affixed to the machine where possible, secured elsewhere if not, and must not be a hazard themselves. Point of operation is where work is actually performed on the material.

0:52 1910.212(a)(3) · Point of operation

If the point of operation exposes an employee to injury, it shall be guarded. Absent a specific standard, the guard must keep any part of the operator's body out of the danger zone during the cycle.

1:11 1910.212 · Fans and drums

Special handtools for placing and removing material only supplement guarding, never replace it. Fan blades must be guarded when the blade periphery is less than 7 feet above the floor or working level. The guard openings can be no larger than one-half inch.

1:29 1910.215 · Abrasive wheels

Revolving drums, barrels and containers need an enclosure interlocked with the drive, so they cannot revolve unless it is in place. Abrasive wheels are used only on machines with safety guards, with narrow exceptions. One exception: mounted wheels in portable operations, 2 inches and smaller in diameter.

1:52 1910.215(b) · Guard exposure

On offhand grinders, the work rest opening is one-eighth inch maximum, so work can't jam and break the wheel. Clamp it after each adjustment, never adjusting with the wheel in motion. Each listed grinder type has a maximum angular exposure of the wheel periphery and sides. Bench and floor stands: should not exceed 90 degrees, beginning not more than 65 above the spindle plane. Contact below it allows 125. Cylindrical grinders: 180 degrees, beginning not more than 65 degrees above the spindle plane.

2:31 1910.215(c) · Flanges

Surface grinders using the periphery, and cutting-off machines: 150 degrees, beginning not less than 15 below the spindle plane. Swing frame and automatic snagging: 180, top half enclosed.

2:51 1910.215(d) · Mounting

Top grinding: 60. Abrasive wheels are generally mounted between flanges not less than one-third the wheel diameter. Type 1 cutting-off flanges are at least one-fourth; Type 27A may be under one-third, but not under one-fourth. Both flanges normally match in diameter. Blotters spread flange pressure, with listed exceptions. Immediately before mounting, the user inspects and sounds every wheel: the ring test.

3:19 1910.242 · Hand and portable tools

Check that spindle speed does not exceed the maximum operating speed marked on the wheel. Tap gently with a nonmetallic implement. A cracked wheel sounds dead and shall not be used.

3:37 On the job

Wheels must be dry. Tap 45 degrees each side of vertical, 1 or 2 inches from the periphery, then rotate 45 degrees and repeat. The employer is responsible for the safe condition of tools, including employee-furnished tools. i. Even then, it requires effective chip guarding and personal protective equipment.

4:02 Common exam traps

You're the safety manager at a fabrication shop. A new wheel is going on an offhand bench grinder, and the work rest looks loose. First, the user ring tests the wheel. A dead sound means it is not used. Next, confirm spindle speed does not exceed the maximum marked on the wheel. Then set the work rest to one-eighth inch maximum, with the wheel stopped, and clamp it. Now, five traps that catch people on exam day.

4:36 Recap quiz

One: handtools only supplement guarding. Two: fan blades under 7 feet are guarded, openings no larger than one-half inch. Three: work rest gap is one-eighth inch maximum, not one-fourth. Four: flanges are generally one-third, with exceptions like Type 1 and 27A cutting-off wheels at one-fourth. , with chip guarding and PPE. Question 1. Maximum work rest opening on an offhand grinder? A: one-eighth inch. B: one-fourth inch. C: one-sixteenth inch. D: one-half inch. A. One-eighth inch prevents the work jamming between wheel and rest. Question 2. A fan's blade periphery is 6 feet above the floor. What is required? A: no guard. B: only if someone is nearby. C: openings up to 1 inch. D: openings up to half an inch. D. Under 7 feet, blades are guarded with openings no larger than one-half inch. Question 3. A bench grinder wheel must be touched below the spindle plane. Maximum guard exposure? A: 60. B: 90. C: 125. D: 180 degrees. C. Contact below the spindle plane allows up to 125 degrees. Want to see where you stand on every ASP domain? com.

25 questions, free, no card. You get a readiness score for each ASP domain.