Manual Polishing Hazard *link*

great white

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http://www.labour.gov.on.ca/english/hs/pubs/alerts/i07.php

Alert: Machine Shop Lathes: Entanglement Hazards During High-Speed Polishing
  • ISSN: 1195-5228
  • Issued: September 1994
  • Content last reviewed: June 2009
Hazard Summary:
A lathe operator was fatally injured while polishing a slotted steel shaft with emery paper. Before putting it in the lathe, he had machined three keyway slots along the 3" diameter shaft. After securing it between the chuck and the tailstock of the lathe he began polishing with a long strip of emery paper looped around the rapidly rotating shaft. The slots caught the strip of paper, which entangled his gloved hand and pulled his arm around the shaft, severing it from his body. He died later from extensive head, neck and chest injuries.

Three similar incidents, all resulting in critical injuries, were reported to the Ministry of Labour in 1993. In all cases, emery paper being used to polish workpieces in lathes entangled the operators' gloves or loose clothing, causing broken arms.

There is a hazard of entanglement whenever lathe operators use emery paper or similar material to sand or polish a rotating shaft with keyway slots or similar slotted profiles. Without warning, the paper may catch in the sharp edges of a slot, fold into the cavity, and wrap itself around the shaft, sometimes entangling the operator's gloved hand or loose clothing.

Locations and Sectors:
The machine tool industry; trade schools.

Recommended Precautions:
Manual polishing of workpieces on lathes shall be done before milling keyways or other slots. (Manual polishing can be done safely either with a file wrapped with emery paper or with an emery paper feeding device that is secured by the tool post.)

Gloves shall not be worn in any situation where they may get entangled in machinery.

The Occupational Health and Safety Act states that an employer shall:

"provide information, instruction and supervision to a worker to protect the health or safety of the worker" (25(2)(a)) and "take every precaution reasonable in the circumstances for the protection of a worker" (25(2)(h)).
The Regulation for Industrial Establishments (R.R.O. 1990, Reg. 851) states:

"Jewellery or clothing that is loose or dangling or rings shall not be worn near any rotating shaft, spindle, gear, belt or other source of entanglement." (83(2))
The following requirements must also be observed by lathe operators and employers:

  • Operators shall wear safety glasses and appropriate foot protection.
  • All power transmission parts shall be guarded.
  • The power to the drive motor shall be shut off before mounting or removing accessories.
As well, the Ministry of Labour recommends that the following safety precautions be taken:

  • Ensure that the lathe has a start/stop button within easy reach.
  • Use a lifting device to handle heavy loads.
  • Ensure that lifting attachments will not become entangled with any moving parts.
  • Ensure that permanent chip and coolant shields are in place.
  • Remove the chuck wrench immediately after adjusting the chuck.
  • Remove all tools, measuring instruments and other objects from the saddle or the lathe bed before starting the machine.
  • Stop the lathe before taking measurements of any kind.
  • Use a brush or rake to remove cutting.
  • Never reach over a rotating chuck when filing.
  • Never use a file without a handle.
  • Never use callipers or gauges on a rotating workpiece.
  • Use a centre support or follow rest while making heavy cuts on long slender workpieces.
  • Maintain adequate working clearances around the lathe, and keep them free of oil and grease.





I just thought it was worth posting. I certainly didn't know, other beginners may not either....
 
Some good advice! Should print it out in 48 pt. type and post it next to the lathe.
 
That's good to keep in mind, even with smaller machines. Sometimes I think people underestimate the torque available at smaller diameters. And naturally, we want to spin the part fast to "shine" it up. All it takes is a few milliseconds for the paper to wrap around enough to touch itself and grab the rotating part. I would imagine this is kind of like the 2 types of bikers there are.....those who have gone down, and those who will. I've had it happen to me a few times, even with all the years I have been at it. But, I have learned never to have too firm a grip on the paper. If the machine want it, that's fine with me. No arguments. What unnerves me is to see someone holding a long piece of paper pinched between one hand, wrapped around the part, and applying pressure with the other hand on the back of the part. This gives the paper an excellent opportunity to get slack enough on the front to grab and wrap. It all happens too fast. I have seen broken fingers and lost hide, but only read about severe cases like mentioned. I'd rather not see or hear of anyone here having any accident.
 
If you think you must use "strip" polishing media, make the strip extra long, no gloves,and hold the strip two fingers at each end........ If it catches, it will be yanked
from your hand.........
 
With key-ways or slots milled into a shaft you would role the edges of the slots trying to polish under power. Big No-No !
I have long respected the power of even very small machines and the tendency of emery to grip and role with the shaft.
That was not an experienced operator.
 
It astonishes me that people insist on wearing gloves around stuff that spins...

I never thought about that angle before. I just don't wear gloves when running a lathe, mill or drill press because I want a good feel for what the tool is doing to the work.

And I totally agree with Tony, a loose grip on the emery or other polishing cloth, If the machine wants it, let it go. Then turn off the machine to recover it.
 
Gloves are a no no, so are rings, jewelry, watches, long hair, etc.
 
I prefer wet and dry paper (no cloth backing) with a very light mineral oil for polishing shafts etc then when it grabs it tears.
I do a lot of polishing with buffing wheels.
These grab the work far to easily.
Be very careful of the long threads that can emanate from the wheel, I usually burn them off as soon as I notice them.
 
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