usma  

[USMA:48354] Fw: Fw: Why no 18 mm Sockets or Wrenches in Standard Metric Sets

John M. Steele
Wed, 11 Aug 2010 05:00:55 -0700

This chart disagrees with the other one I consulted (and I probably trust this more):
http://www.sizes.com/tools/socket_wrenches_metric.htm
 
It says 18 mm is strictly an ANSI spec head, all other specs use 17 mm or 19 mm heads for 12 mm bolt.  However it does show 18 mm sockets as available in the US, which agrees with the fact I have them.  If anybody uses ANSI spec fasteners, it should be Americans, and the tools to fit should be available here (unless they are all made in China). :)

----- Forwarded Message ----
From: John M. Steele <jmsteele9...@sbcglobal.net>
To: trus...@grandecom.net; U.S. Metric Association <usma@colostate.edu>
Sent: Wed, August 11, 2010 6:51:25 AM
Subject: Re: [USMA:48350] Fw: Why no 18 mm Sockets or Wrenches in Standard Metric Sets

My open-end wrench set and my half-inch drive socket set both include 18 mm (I checked), so I can't relate to the statement they aren't sold here.  In ANSI/ISO thread spec, 18 mm is the A/F (across flats) head size for a 12 mm bolt.  In the DIN and JIS standards, 18 mm is not used, they jump from 17 mm to 19 mm.  It might depend on where the set was made, and screw standard they assumed.
 
Both sets mentioned above are Craftsman brand, so Sears is one possible source.  Also, it is possible to buy individual sockets and wrenches for sizes not included in the sets.
 
PS: American cars are pretty metric.  An occasional US fastener may be found on a purchased module or subassembly, but I doubt you would find many installed by the OEM.

From: Paul Trusten <trus...@grandecom.net>
To: U.S. Metric Association <usma@colostate.edu>
Sent: Wed, August 11, 2010 3:03:23 AM
Subject: [USMA:48350] Fw: Why no 18 mm Sockets or Wrenches in Standard Metric Sets

Randy,  I am posting your question to the USMA listserver, and I'm confident that one of our list subscribers will have an answer for you and reply to your question.
 
Paul
----- Original Message -----
Sent: 10 August, 2010 11:45
Subject: Why no 18 mm Sockets or Wrenches in Standard Metric Sets

Dear Paul,

I have a question my father asked about metric. Here in the US socket and wrench sets are sold without 18 mm, yet my father needs that a lot to work on various machines. I checked my own set and indeed it goes from 17 to 19 mm with no 18 mm. I had a friend who claims it was to keep Americans from using certain sockets on American (non-metric) cars and stripping them out. If you have any idea let me know.

Thanks,

Randy
--
Randy Bancroft   P.E
Randwulf Technologies
2837 Perry Street
Denver, CO  80212
Cell (303)-507-9889
www.randwulftech.com