I came across a set of these Proto wrenches with unfamiliar markings. The wrenches are combinations (open on one end and box on the other, the same size on both ends), but I don't know how to read the markings. The wrench in the picture measures out as a 13/16 on both ends. Any help on the marking would be appreciated. J
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Unknown wrench markings
- Thread starter GT6cops
- Start date
Conductor562
Well-known member
I'm on a mobile and can't see the pic very good. I addition to the size, there should be a date code consisting of 2 letters, and a model #. Anything beyond that (with the exception of PROTO and USA or Los Angeles) would be somewhat unusual and may indicate a tool made under a specific contract.
Wish I could see the pic better.
Wish I could see the pic better.
Conductor562
Well-known member
1216 is the model # for 13/16. Been in use forever.
I want to say BS is your date code. Not sure off the top of my head, but I can tell you it's after 1956 and the registered symbol tell me it likely IR era. The reason I 2nd guess the BS date code theory is because of the fact that it's repeated twice.
As for the 1/2 and 7/16 markings, do me a favor. Measure the beam of the wrench. If it's 1/2" wide and 7/16" thick I believe we may have our answer.
I want to say BS is your date code. Not sure off the top of my head, but I can tell you it's after 1956 and the registered symbol tell me it likely IR era. The reason I 2nd guess the BS date code theory is because of the fact that it's repeated twice.
As for the 1/2 and 7/16 markings, do me a favor. Measure the beam of the wrench. If it's 1/2" wide and 7/16" thick I believe we may have our answer.
neophyte
Well-known member
1/2 inch British Standard, 7/16 inch Whitworth.
Whitworth and British Standard were standards used for fasteners and threads in Britain. The hex heads of bolts were standardized to the size of the threads. Whitworth was a coarser thread used for iron bolts, British Standard was a finer thread used for steel fasteners. A 1/2 inch British Standard wrench/spanner was used to turn the head on a 1/2 British Standard bolt, but the across the flat dimensions were not 1/2 inch. The British Standard fasteners typically had a head size that was one size smaller than the Whitworth fasteners, so a wrench made for the head on a 7/16 inch Whitworth fastener, would turn the head on a 1/2 inch British Standard fastener. The Whitworth bolt head dimensions were typically measured in decimal inches. A 7/16 inch whitworth wrench should have a jaw size of .820 inches, just over 13/16". This chart shows size comparisons and likely has a less convoluted answer.
Whitworth and British Standard were standards used for fasteners and threads in Britain. The hex heads of bolts were standardized to the size of the threads. Whitworth was a coarser thread used for iron bolts, British Standard was a finer thread used for steel fasteners. A 1/2 inch British Standard wrench/spanner was used to turn the head on a 1/2 British Standard bolt, but the across the flat dimensions were not 1/2 inch. The British Standard fasteners typically had a head size that was one size smaller than the Whitworth fasteners, so a wrench made for the head on a 7/16 inch Whitworth fastener, would turn the head on a 1/2 inch British Standard fastener. The Whitworth bolt head dimensions were typically measured in decimal inches. A 7/16 inch whitworth wrench should have a jaw size of .820 inches, just over 13/16". This chart shows size comparisons and likely has a less convoluted answer.
Last edited:
Conductor562,
No soap!, the beam measures 11/16 wide and 1/4 thick. I find it mystifying that the wrench has no obvious markings as to its 13/16 size - only if you know that 1216 is the model number do you know the size - not too user friendly. J
No soap!, the beam measures 11/16 wide and 1/4 thick. I find it mystifying that the wrench has no obvious markings as to its 13/16 size - only if you know that 1216 is the model number do you know the size - not too user friendly. J
neophyte
Well-known member
1216 is the model # for 13/16. Been in use forever.
I want to say BS is your date code. Not sure off the top of my head, but I can tell you it's after 1956 and the registered symbol tell me it likely IR era. The reason I 2nd guess the BS date code theory is because of the fact that it's repeated twice.
As for the 1/2 and 7/16 markings, do me a favor. Measure the beam of the wrench. If it's 1/2" wide and 7/16" thick I believe we may have our answer.
If 1216 is a standard number for a 13/16" wrench, Proto likely used the standard blank from a 13/16" wrench and broached the blank to the Whitworth/British Standard dimensions rather than making a completely different set of dies for Whitworth wrenches.
NHBandit
Well-known member
Spent more than half my life wrenching on old Triumph motorcycles. Those are for working on British stuff as already posted. Just recently sold off my Snap On Brit stuff when I sold my last British bike.