The 5.5 mm is a rare size, I believe it is the only metric size that has a .5 between sizes.
Why are SAE sockets formatted in fractions?
- Thread starter Crash Bandicoot
- Start date
Aren't Ford headlight adjusters 4.5mm?
That would be a good one to round off. 16-9/16" would be close.
The local broadsheet used to have syndicated home projects on Saturdays. The articles came from the U.S., and someone on the Canadian side would do a hard conversion on the units.
Typical example: "Take a piece of pine about 60.96 cm long and about 76.2 mm wide ..."
The American article would have said about 2' (or 24") long and about 3" wide.
Given that the measurements were approximate ("about"), a conversion to four significant figures was misleading.
And given that most Canadians can easily flip back and forth between Imperial and SI anyway, the conversion was completely unnecessary.
I still remember the owners manual for my Saturn. If the oil level was low by 3.76mm, it was time to add.
"Thought it were time to add, but it were only down 3.73 mm. Let 'er run as she is!"
The SAE ( Society of Automotive Engineers) was established in the USA in 1905. At the time there were all sorts of ways of describing wrench sizes. The SAE adopted the standard SAE sizes we see to this day. In 1975 the USA adopted the metric system and the automobile industry switched over but for quite a while there were cars with both SAE and metric fasteners. Looks like they’re all metric now.
If you're familiar with tape measures using feet and inches, sure. If your only exposure is metric, 27/50 isn't wrong at all.
WRT SAE vs metric, I find it interesting that the world has no choice when it comes to ratchet and breaker bar drive sizes. It's either 1/4", 3/8", 1/2", 3/4", etc.
Which also reminds me I need to post a picture of a 3/4" drive Craftsman ratchet I saw in my FIL's toolbox the other day. He's a retired owner/operator OTR trucker and has a set of BIG TOOLS.
Which also reminds me I need to post a picture of a 3/4" drive Craftsman ratchet I saw in my FIL's toolbox the other day. He's a retired owner/operator OTR trucker and has a set of BIG TOOLS.
Also known as 6.35 mm, 9.53 mm, 12.70 mm and 19.05 mm drive ratchets. Go into a parts store and ask if they have any 9.53 mm drive ratchets.
It's not wrong, but it is awkward. If one doesn't want to round to a common fraction, 16.54" works better (for me) than 16-27/50".
I was gonna say better to not round down to 16.5, and best not to LCD. Just use 100ths. 16.54"
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To someone in the metric world, what is a "common fraction", specifically when related to a tape measure or ruler ?
A common fraction would be in the format of x/2, x/4, x/8, x/16, x/32, x/64.
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I consider any fractions down to 16ths of an inch common, 32nds and beyond not so much. This is my personal opinion only, likely based on my ye olde SAE sockets and wrenches.
Note that all SBC bores and strokes fit this pattern until the great heresy when the 327 was stroked to 3.48" to create the 350. Even at that, at least they didn't say the stroke was 3-12/25".
Edit: I think all Imperial/SAE fractional denominators should be 2^x (in the automotive world). Just my eight farthings.
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I have a 2.5, 3.5, 4.5 and 5.5 from my ancient days repairing Compaq laptops that used rediculous jewelry sized garbage
Even better are small metric torx.
Why ? Those are socket / wrench sizes. Outside of the US (and Canada), how common do you think SAE tools are ?
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