After measuring some wrenches around the house, I was wondering what exactly constitutes a "tight" fit on a fastener? Several snap-on and craftsman open ends measured .006 and .007 over their listed size, while some measured as tight as .005 and as wide as .010. For example, a 1/2" combo wrench whos open end actually measures .507. This leads me to wonder what is considered a tight fitting wrench?
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Wrenches: What constitutes a tight fit?
- Thread starter Kyle86
- Start date
Min opening = 1.005W + 0.001in
Max opening = 1.01W + 0.005in
W is the basic width of the nut flats (ie max nut size)
Tor 1/2" the range should be .5035 - .5100"
This is for SAE, Metric is a bit different but similar.
So tight would be anything under .5035"
Max opening = 1.01W + 0.005in
W is the basic width of the nut flats (ie max nut size)
Tor 1/2" the range should be .5035 - .5100"
This is for SAE, Metric is a bit different but similar.
So tight would be anything under .5035"
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HandyManny
Well-known member
I believe the tolerances should be no more than .010" over the actual size of fastener (actual size it is supposed to be). Anything tighter than .005" and you are going to have a hard time getting the tool onto a dirty fastener. There needs to be space there, just no more than .010"
That is a decent rule of thumb but the larger wrench sizes will have even larger openings.
ANSI/ASME B18.2.2-1987 from Machinery Handbook 26 says 1.005W + 0.001 is Minimum wrench opening and 1.010W + .004 is Maximum wrench opening. Bolts also have tolerance.
See example above, for 1/2" bolt head size, the tolerance would range from .004" to .021" and still be considered in tolerance.
The wrench can range from 0.504" to 0.510"
and the bolt can range from 0.489" to 0.500".
When the bolt size is larger the wrench can have a lot more tolerance and still be within spec.
For instance a 1" wrench should never be smaller than 1.006" and can go up to 1.015" before it is too large. Again, keep in mind the fastener will ADD to this tolerance in almost every case because it is supposed to be smaller than the nominal bolt head size.
ANSI/ASME B18.2.2-1987 from Machinery Handbook 26 says 1.005W + 0.001 is Minimum wrench opening and 1.010W + .004 is Maximum wrench opening. Bolts also have tolerance.
See example above, for 1/2" bolt head size, the tolerance would range from .004" to .021" and still be considered in tolerance.
The wrench can range from 0.504" to 0.510"
and the bolt can range from 0.489" to 0.500".
When the bolt size is larger the wrench can have a lot more tolerance and still be within spec.
For instance a 1" wrench should never be smaller than 1.006" and can go up to 1.015" before it is too large. Again, keep in mind the fastener will ADD to this tolerance in almost every case because it is supposed to be smaller than the nominal bolt head size.
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Is there a standard for expansion under torque?
That would be a trait of the type of steel used in manufacture ie: chrome alloy, chrome vanadium, stainless etc. and the type of tempering used in the hardening process of each manufacturer.
fury9
Well-known member
to me a tight fitting wrench is a six point on a nut that doesn't wiggle too much
So at what size would a wrench be considered worn out or defective?
Max opening = 1.01W + 0.005in
W is the basic width of the nut flats (ie max nut size)?
Is there a standard for expansion under torque?
The first question is answered by your second question, and no, but there are standards for tool clearance from obstructions.