Originally Posted by
Curt Harms
A number of years ago Grizzly fasteners had metric threads but SAE sized (or so it seemed) heads. I guess the thinking was that most purchasers wouldn't have metric tools. I haven't bought any Grizzly machines in a long time so don't know if that is still true.
Many of the more common sizes of bolt heads have close equivalents in the SAE and metric world. The most frustrating exceptions are 3/8" & 10mm. Both sizes are common.
A mechanic friend told me a long time ago if a complete metric tools set was purchased there were about four SAE sizes that would be needed to have a complete set of tools for both. If a full set of SAE tools were purchased there would be seven wrenches needed to complete a set to use for both systems.
jtk
Just for the heck of it here is an equivalent chart of mine made up in the past:
Metric to SAE wrench sizes. 6.5mm is common in many wrench sets. A t next to the wrench size indicates this wrench will be tight on its equivalent size nut, i.e. a 14mm wrench is snug on a 9/16 nut.
Millimeters Inch
6 ------- N/A
6.5 ------- 1/4t
7 ------- N/A
8 ------- 5/16
9 ------- 11/32t
10 ------- N/A
11t ------- 7/16
12 ------- N/A
13 ------- 1/2t
14t ------- 9/16
15 ------- 19/32 (not common)
16 ------- 5/8
17 ------- N/A
18 ------- N/A
19 ------- 3/4 (This is such a perfect match, it is used internationally for automobile wheel nuts)
20 ------- N/A
21 ------- N/A
22t ------- 7/8
32 ------- 1-1/4 If memory serves me well, this is the size of the hub nut on the rear axle of Volks Wagons before '68 or so.
That has 7 metric sizes throughout the range not covered by an SAE wrench set.
3/16 would be tight on a 5mm, neither size is included with most sets.
Three common SAE sizes, 3/8, 11/16 and 15/16 are not covered by the metric sizes.
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)