Machine Hazards and Housekeeping
The two ways a machine injures you - it catches hold and pulls you in, or it closes on you - plus the environment around it and the habits that keep both off you.
Rotating machinery
Rotating machinery
Rotating machinery injures you by catching hold of something and pulling it in. It does not have to catch your hand. It catches a sleeve, a glove, a lanyard or a strand of hair, and your hand goes wherever that goes.
Gears, pulleys and belts, chains and sprockets are extremely dangerous. Where a rotating part meets another surface there is a wedge that closes to nothing — an in-running nip point, the place the machine feeds things into itself. It is where the belt runs onto the pulley, where the chain runs onto the sprocket, where the gear teeth mesh.
The contact and the injury happen in different places. You touch the belt out in the open, where it looks like a moving strap; the belt carries you to the pulley, where there is no gap at all. That distance is why staying clear of the nip point is not enough on its own — anything the machine can grip is a handle it uses to bring you there.
What gets caught
- Loose clothing, jewelry and unsecured hair — see clothing, jewelry and hair.
- Gloves. Gloves or rags are for handling sharp objects such as cutters, and only once the machine is shut down. NEVER wear gloves at a running machine — a glove catches where bare skin would pull free, and takes your hand with it. See chips and gloves.
- A long stringy chip still connected to the cut — see Metal Chips and Swarf.
It does not take teeth, and it does not take speed. A plain smooth shaft turning slowly will still wind hair or cloth onto itself, and once it has a turn or two it does not let go.
The word for this, and where it comes from
“Nip point” is not shop slang. It is the term the machine-guarding standard uses. 29 CFR 1910.212(a)(1) requires guarding against “hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks.”
OSHA’s Machine Guarding eTool puts it plainly: “In-running nip point hazards are caused by the rotating parts on machinery.” Its longer treatment, Concepts and Techniques of Machine Safeguarding (OSHA 3067), gives three kinds:
- “Parts can rotate in opposite directions while their axes are parallel to each other. These parts may be in contact (producing a nip point) or in close proximity.” — meshing gears.
- “Nip points are also created between rotating and tangentially moving parts. Some examples would be: the point of contact between a power transmission belt and its pulley, a chain and a sprocket, and a rack and pinion.”
- “Nip points can occur between rotating and fixed parts which create a shearing, crushing, or abrading action.”
So belts, chains, sprockets and gears are rotating hazards by name. What makes them dangerous is that they draw material in — not that two parts close on each other.
OSHA is just as direct about the plain shaft: “Rotating motion can be dangerous; even smooth, slowly rotating shafts can grip hair and clothing, and through minor contact force the hand and arm into a dangerous position.”
These parts are meant to be behind covers, and the standard is specific about it — 29 CFR 1910.219(f)(3): “All sprocket wheels and chains shall be enclosed unless they are more than seven (7) feet above the floor or platform.”
The rotating parts that have no cover
Belts, gears and chains belong behind covers. The working end of a machine does not. The spindle — the driven shaft the motor turns — the chuck that grips the tool or the work, and the stock (the raw material) held in it all turn out in the open. Nothing is between you and them, because you have to reach them to do the job.
So everything above about what gets caught applies here with nothing in the way — and it applies to every machine that turns, not only the loud ones. A drill press is quiet, it is slow, and it looks like the harmless one. It is still an open chuck spinning, and it will wind hair, a sleeve or a glove onto itself like anything else. Slow is how long it takes, not whether it happens.
The lathe is where this goes furthest, and the reason is what a lathe is. Most machines hold the work still and move a cutter across it; a lathe does the opposite and turns the work. What is spinning in the open is then not a bit the width of a pencil — it is the whole part, as long and as heavy as that part happens to be. That is why the fatality reports for lathes describe something other than a hand injury: a person wound onto their own workpiece.
The question, before anything is switched on: what is turning, and what of mine can reach it? A sleeve, a glove, loose hair and a strip of abrasive cloth held against the work have each pulled somebody into a machine. Every one of them is easier to deal with before the spindle is turning than after.
None of this is a ranking. The mechanism is the same on every machine that turns, and the one that can catch you is whichever one you are standing at.
What the investigations actually describe
Oregon’s state fatality-investigation program, summarizing the record for this class of machine: “The most common causes of death and injury from metal lathes include entanglement of clothing in moving parts, being hit by loose objects on the lathe (e.g., chuck keys, tools, metal shavings) and being struck by a part that has not been adequately secured.” (OR-FACE 2012-18-1, Experienced Journeyman Machinist Killed While Operating an Engine Lathe, 2014.)
Four investigated deaths, all the same event — something attached to a person touched something turning, and the machine did the rest:
- Smoothing a part while it turned. A 69-year-old machinist with over 30 years’ experience “reached over the work piece to smooth out a radiused transition with emery cloth and a file in hand” and “his loose clothing (left arm sleeve) became entangled around the rotating work piece”. A co-worker 30 feet away heard “a strange ‘winding-up’ sound”. Of that same part, the shop foreman had said that “the rough surface could grab clothing or gloves”. (OR-FACE 2012-18-1.)
- Stock sticking out the back of the spindle. A 52-year-old machinist was set up on a 103-inch steel bar: “Due to the length of the material, 24 inches were sticking out the back of the lathe, unguarded, and held in place with a clamping device that rotates as the lathe rotates.” He reached across the running machine and “the sleeve of his shirt became entangled”. (Kentucky FACE 21KY002, 2021.)
- A burr on the end of the bar. A lathe operator in his twenties had a 1 7/8-inch stub of 1-inch bar standing past the tailstock. “The right pocket of his shirt was caught by the rotating tailstock burr. His shirt wrapped around the stock and tightened at the decedent’s neck and chest.” The listed contributing factor is “walking to and/or reaching over unguarded rotating bar stock”. OSHA makes the same point in general: the danger “increases when projections such as set screws, bolts, nicks, abrasions, and projecting keys… are exposed on rotating parts.” (Michigan FACE 14MI034, 2014; OSHA Machine Guarding eTool.)
- A drill press. “As Employee #1 reached into the unguarded point of operation, his shirt sleeve or gloves became entangled in the drill bit. Employee #1 was pulled toward the machine, entangling Employee #1’s long hair. The drill press continued to spin, completely pulling Employee #1 into the operating area.” She died of her injuries. The same report records that the spindle “had speeds that ranged from 45 to 1115 rotations per minute”. (OSHA accident 114097.015, 20 February 2019.)
Why abrasive cloth keeps appearing. The UK Health and Safety Executive publishes a sheet on this one task: “Every year there are serious accidents involving the use of emery cloth on metalworking lathes. These accidents result in serious injuries such as broken bones, dislocations, lacerations, amputations and occasionally death.” The mechanism it names is the one above: “Accidents occur when hand-held emery cloth is entangled in the rotating parts of the machine or where the emery cloth is snagged on the rotating component dragging the operator into the danger zone.” Its own rules are that emery cloth “should NEVER be applied directly by hand on manual metalworking lathes”, and that gloves “increase the risk of entanglement and” are “never acceptable near rotating parts of machinery”. (HSE Engineering Information Sheet No 2, rev 1, 2015 — that is HSE’s guidance; ask what the procedure is in the shop you are standing in.)
And the drill press is not the exception it looks like. OSHA’s own drill-press training script lists, among the ways accidents happen, “getting dangling jewelry, loose clothing, or hair caught in the drill chuck (rotational hazard)”, and states: “The primary hazards of drill presses are contact at the point of operation and rotational hazards. An operator can risk serious hand injury when working too close to the drilling area, wearing gloves, loose clothing, loose hair, or jewelry.”