[Hallb-engineering] Fwd: Lathe Chuck Jaw Near-Miss

Douglas Tilles tilles at jlab.org
Fri Feb 15 15:14:20 EST 2013

----- Forwarded Message -----
From: "Tina Johnson" <cjohnson at jlab.org>
To: "Scott Thompson" <thomps at jlab.org>, follkiej at jlab.org, delk at jlab.org, brockj at jlab.org, hoegerl at jlab.org, "Chris Holdzkom" <holdzkom at jlab.org>, "Christopher Keith" <ckeith at jlab.org>, "Tom Carstens" <carstens at jlab.org>, "Ed Folts" <folts at jlab.org>, "Doug Tilles" <tilles at jlab.org>, "Walter Kellner" <kellner at jlab.org>
Cc: cjohnson at jlab.org, "Bert Manzlak" <manzlak at jlab.org>, "Henry Robertson" <robertsn at jlab.org>, "Steve Neilson" <sneilson at jlab.org>
Sent: Friday, February 15, 2013 3:05:58 PM
Subject: Lathe Chuck Jaw Near-Miss


Following a recent "Near-Miss" event in the Machine Shop, we are asking that you please share the following information with your work groups.  If you have any questions or concerns, feel free to contact me. 

IMPORTANT- Please Share With Your Work Group 


On 12 February 2013 approximately 10:00 a.m., a shop worker was chucking up a part to face- off (i.e., to machine a surface perpendicular to the centerline of the lathe).   He was using a six inch, six jaw precision chuck.   During the process of turning on the lathe spindle, three of the chuck jaws were expelled from the chuck.   One hit him in the forehead causing a minor laceration.   The second hit the wall behind the lathe.   The third on landed in the lathe’s chip pan.   He started the lathe in low gear, which, in hindsight, helped to minimize damage.   The items below contributed to the event: 

A)    The chuck was opened beyond the maximum diameter recommended by the manufacturer and it was not marked with the maximum opening diameter for the configuration used.   This has been corrected with a witness groove machined in the face of the chuck. 

B)     The machinist did not stand to one side before starting the lathe and the sign on the lathe had been worn off by use.   New signs have been affixed to the lathe head and chip guard. “Do not stand in line of chuck when starting”. 

C)     The three jaws that were ejected from the chuck would have fallen out if the machinist had manually rotated the chuck before starting the lathe, and if the chuck had not been bound up with dirt, dried coolant, and grease.   The chuck was thoroughly cleaned before reuse 


Thank you in advance, 
Tina Johnson
Reporting Officer/
Administrative Assistant
JSA/Jefferson Lab
12050 Jefferson Ave
Suite 602
Newport News, VA 23606
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