All late model cars that I have worked on, whether it be American, Japanese, German or other seem to have all metric fasteners. It does not seem to matter what type of fastener is used, whether it be a regular 6 point hex bolt, 12 point nut, allen, Torx or triple square (XZN), they are all metric. I have a set of standard (fractions of inch) allen, 6 point and 12 point sockets that I have used maybe 10 times in the last few years. Is the industry standard now metric fasteners only? Anyone know of any examples of anything built new today (motorcycles, boats, refrigerators) that still uses standard fasteners?
yes.
not a specific example, but anything which uses pipe threading might still work in fractional.
The semiconductor manufacturing equipment made by the company that I work for does.
I forget what, but I recently ran into something fairly new with fractional fasteners. What amazes me is the good stock of fractional fasteners and SAE wrenches still sold. Last I looked, even the 3/16’’ screws seem to have gone back to #10’s, or at least the labels.
I just redid the front brakes on my 02 Cavalier. The caliper bolts have 3/8’’ Allen heads. Only fractional thing I have found on it. Well maybe some of the sheet metal screws are.
Generally anything used in construction is still in non-metric sizing. Especially things that have to fit together with existing systems (like plumbing, electrical, etc.) Even basics like wood, concrete blocks, or bricks. They still use 2x4’s, for example (though the manuracturers have downsized them from real 2 inches by 4 inches now).
2x4 is the unfinished size. The finished size is 1.5 x 3.5.
Lumber sizes have been “nominal” for a long time. For that matter, the actual sizes have steadily become smaller.
In answer to the OP’s question. Harley Davidson motorcycles still use SAE sized fasteners.
That’s the current finished size. It used to be 1.75 x 3.75. The lumber industry tries to claim that it is the finishing from a rough cut that makes it smaller, but that is untrue. If you go to an actual lumber mill (like we have in northern Minnesota), they start out by cutting them smaller than 2 x 4 inches. That’s why the size decreased – it isn’t like the smoothing finishing used to take off 1/4 inch, and now takes 1/2 inch – lumber is no smoother than before.
(Also, there was a time when they were actual full size 2 x 4’s. I once did some work in my grandmothers house (built pre-1900) and things did not fit right. Ended up I had allowed for ‘nominal’ 2 x 4’s, while the ones in the house were actual full size!)
Some of the screws in PC cases use US thread sizes (HDD mounts for example). Others are metric.
When did you come across the sizes you expressed? (1.75"x3.75") I’m not doubting that you ran into lumber of that size, it’s just that it must have been quite some time in the past. I haven’t encountered lumber of that size, straight from the lumber yard or mill, in a very long time. Treated lumber, on the other hand, can be bigger than the normal or finished size (1.5" x 3.5") due to swelling from the chemicals injected under pressure, but rarely more than 1/8" (in my experience) and it will generally shrink back down to normal size after drying.
And speaking of “not fitting right”, the framing dimensions have changed over the years, as well. Houses built (approx.) pre-1930 (It depends on what part of the country you’re talking about) used different spacing measurements for the rough framing members. The standard today is 16" o.c. (on center) for wall studs, in previous times 20" o.c. was the standard.
(My fathers house has those measurements. Built in 1930 in Houston, Texas)
By the way. Interesting link, Beowulf. Thanks! 
hand tools are easier to explain in that there are still billions of things out there that were originally manufactured with non-metric fasteners. So fractional tools will be sold for a long time to come.
it doesn’t explain your caliper bolts, but one other thing to keep in mind is that there are some sizes of metric screw heads that are close enough to fractional that they seem almost identical. 8mm=5/16", 13mm=1/2", 16mm=5/8", and so on. They’re not truly identical, but frequently close enough.
as for sheet metal screws, since they’re intended to go in non-tapped/non-sized holes, I guess it doesn’t matter as much.
As far as hex head bolts are concerned, the only size that I’ve come across that is consistently interchangeable, as regards the wrench that will fit, is the 9/16" = 14mm.
True, you can get some metric wrenches to fit SAE hex heads and vice versa, but if they’re torqued very tightly, you run a serious risk of rounding off the bolt head.
And that sucks, massively! :mad:
Commercial aviation aircraft built by Boeing and Airbus use standard fasteners and all measurements used in construction of the aircraft is in inches.
Well, for Airbus: fasteners and frame pitches are in standard inch measurements when converted back to imperial, but by and large the rest is metric-based (at least from the A380 and newer, not sure about the older programs) and the working units for Airbus are metric. For example, standard profiles and sheetmetal thicknesses are all in tenths of a millimeter as defined, not a hard conversion from imperial standards.
NB
My GMC Sierra has a mixture of metric and SAE sizes. I need both sets of tools all the time. And remember, a few sizes are near duplicates such as 1/2" and 13mm.
:dubious:
See post #13. Using a wrench or socket that doesn’t fit properly can cause something that started out as a relatively simple repair job. 
To suddenly transform into an unholy nightmare, of rounded off bolt heads and nuts, elevated blood pressure, bruised and bleeding knuckles and a vastly inflated, final cost. :eek: :mad:
At least, it did for yours truly. :smack:
Harley-Davidson: where archaism is a virtue!
Anything manufactured in America is gonna have standard fasteners - by anything I really mean an incredibly small subset of anything - more like, things which are custom built for an application in a factory or warehouse actually in America.
I worked for a company where we built machines for customers and we used standard. Metric is the devil according to them.
I just wish it’d become national policy to switch everything already. Standard is old school. I hate fractional - guessing sizes by sight is the biggest pain in my ass at work.
Uh, not necessarily. We have suppliers that have factories that build our factories, and every non-plumbing fastener that we specify is metric. There are only a very few things that are standard any more. Heck, “standard” is a misnomer these days, as our standard is metric. Because we still follow OSHA and MIOSHA, though, some of our specs are still standard, such as the height of safety barriers in feet and inches. Interesting, the CSA (Canada) publishes virtually all of their standards in non-metric units, too.