Why are SAE sockets formatted in fractions?

[D60]

To go back to your given examples, "SAE" is a common term to refer to fractional hardware and tools.

Nobody is selling "break pads" by that spelling. It's not an accepted term, no matter how many dopes have used the wrong word.

So much this. I was trying to stay out of the pedantic weeds, but I would argue saying "SAE" is more akin to calling a supercharger a blower or an aggressive cam a bumpy stick.

Basically, it's slang and while it shouldn't fly in a technical white paper, we all know what it means in a forum like this which is more like casual conversation among, well, bench racers (keyboard racers) than your final dissertation for an engineering degree.

Next pedantic argument: "Nothing 'flies' in a technical written paper, dude!" Yep, that's because it's a figure of speech and does not refer to any physical object actually taking flight.

 

[ZeeOSix]

So much this. I was trying to stay out of the pedantic weeds, but I would argue saying "SAE" is more akin to calling a supercharger a blower or an aggressive cam a bumpy stick.

If you read the link in my last post, the fastener industry has been using the term "SAE fasteners" (which require the matching SAE tools) ever since the early 1900s. The SAE standardize that fastener and tool system for the American auto industry a very long time ago, and that's why the term "SAE fasteners and tools" is entirely valid and accurate.

 

[Lenny5160]

If you read the link in my last post, the fastener industry has been using the term "SAE fasteners" (which require the matching SAE tools) ever since the early 1900s. The SAE standardize that fastener and tool system for the American auto industry a very long time ago, and that's why the term "SAE fasteners and tools" is entirely valid and accurate.

It's a valid pedantic argument to state that current SAE standards use metric measurements, so saying "SAE" to mean "not metric" is inaccurate. But, we all know what it means and I really can't recall tools being differentiated by any other terms.

 

[ZeeOSix]

It's a valid pedantic argument to state that current SAE standards use metric measurements, so saying "SAE" to mean "not metric" is inaccurate. But, we all know what it means and I really can't recall tools being differentiated by any other terms.

Yes, the SAE has defined both English/Imperial fasteners and also metric fasteners, but the Imperial system was used by SAE way before metric came along in the US automotive industry. Obviously, the fasteners and tools that use factional inch measurements (the English/Imperial system) are different than the fasteners that use the metric system. My argument is that the term "SAE fasteners" is not a "made-up" definition of the fasteners and tools by "bench racers". The term is used because the SAE is officially behind it all, not "bench racers".

 

[Exhaustgases]

Yes ! I liked that link above.
So it is interesting that those SAE wrenches were not marked in inch fractional bolt head dimensions. As written here.

(((((Finally, another wrench stamped SAE, with ends marked 3/8 and 7/16. In fact, the 3/8 end measures .570 inch (instead of .375") and the 7/16 end measures .640 inch (instead of .4375). Again, a sloppy fit on a 9/16" and 5/8" A/F bolt head. These are exactly the A/F dimensions specified under the SAE criteria for these diameters of bolts. )))))

 

[ZeeOSix]

Yes ! I liked that link above.
So it is interesting that those SAE wrenches were not marked in inch fractional bolt head dimensions. As written here.

(((((Finally, another wrench stamped SAE, with ends marked 3/8 and 7/16. In fact, the 3/8 end measures .570 inch (instead of .375") and the 7/16 end measures .640 inch (instead of .4375). Again, a sloppy fit on a 9/16" and 5/8" A/F bolt head. These are exactly the A/F dimensions specified under the SAE criteria for these diameters of bolts. )))))

They went for a sloppy fit back in those days. Guess they liked rounded off hex bolt heads, lol.

 

[Rmay635703]

Torque specs are way more complicated than that, regardless if the fastener is SAE or metric.

They are and they’re also not so long as you have hard joints and best practices followed. If your not building a toaster use grade 8, flanged, spiralic or deformed, coarse thread, then the torque range is always the same.

American here - the metric system is far, far superior, logical, and easier to use.

Metric measurements are superior, metric hardware standards are absolutely horrific.

SAE you have one common standard, metric there are a dozen competing ones.

They went for a sloppy fit back in those days. Guess they liked rounded off hex bolt heads, lol.

Coated and flanged fasteners used to have immense variations allowed, good riddance to grade 2, cast and DAC

Sadly pipe thread (and other) fittings have minimal control on the outer diameter so you still have to deal with sloppy fit up.

It's a valid pedantic argument to state that current SAE standards use metric measurements, so saying "SAE" to mean "not metric" is inaccurate. But, we all know what it means and I really can't recall tools being differentiated by any other terms.

You do realize most metric fasteners do not follow SAE standards?

See this chart (available various places online) of some of the metric hardware standards you are forced to commonly use in the US commodity market.

How many do you suppose are SAE?

Metric has a British metric
a German metric and Asian metric and
a French metric which are at the same time sort of comparable/ compatible but also may require completely different tools to install.

This moronic assembly of standards is why metric costs more and is more prone to error in the real world.
If you say choose one and stick with it, first expect to double hardware costs and second which one? Everybody is doing their own thing. Not much different than 120 years ago before SAE existed or the difference between USS AG VRS SAE standards

 

[burbguy82]

Not coming up in something like the construction world, I also struggled until I went to school for machining.

We were forced to memorize all fractions in 1/16ths, and then that made it easy for me. Now I can relate fractions without thinking about it, but if I'm doubting myself I'll confirm that yes, "eight twelve" is indeed more than "seven-fifty" and so on.

I know most of the 32nds in fractions, too. Handy for measuring holes with calipers and immediately knowing what that translates to.

Oh and friends don't let friends use calipers with a fractional readout. That's like clip-on ties or velcro shoes

I dont even understand fractional readouts on calipers, more specifically, why they are even offered.

A handle moves in .001, or at least mine does.

Point being, if the measurement you are taking is so vague, that the nearest number fractionally will do, you dont really need a caliper, you need a tape measure.

 

[D60]

I dont even understand fractional readouts on calipers, more specifically, why they are even offered.

A handle moves in .001, or at least mine does.

Point being, if the measurement you are taking is so vague, that the nearest number fractionally will do, you dont really need a caliper, you need a tape measure.

Yep, a 64th is about 15 thou which is a mile in caliper-land

Try putting in pistons that are +/- .015. (although, granted, you wouldn't use calipers to measure exact sizing of a piston)

 

[burbguy82]

Yep, a 64th is about 15 thou which is a mile in caliper-land

Try putting in pistons that are +/- .015. (although, granted, you wouldn't use calipers to measure exact sizing of a piston)

Most of the machining i have done is firearm based. For instance, in AK barrels, typically the size of the trunnion on most 762x39 guns is .906, and they are a press fit. Typically the size of the barrel is about 1.5-2 thou over. .001 is what i like for a nice fit, and man what a difference it makes with pressing.

.0005 makes a big difference.

.015 might aswell be a mile.

 

[Kira]

Just for reference:
There's an O-ring on the neck of a 2xAA Maglite. It seals against the inside of the reflector.
You turn said reflector to turn the light on.

That O-ring is 7/128" and is the only thing I ever saw sized with a 128 denominator.

 

[Rmay635703]

Most of the machining i have done is firearm based. For instance, in AK barrels, typically the size of the trunnion on most 762x39 guns is .906, and they are a press fit. Typically the size of the barrel is about 1.5-2 thou over. .001 is what i like for a nice fit, and man what a difference it makes with pressing.

.0005 makes a big difference.

.015 might aswell be a mile.

Press fit we had -100F cooling and an oven a few parts still needed the press and you only got 1 chance

 

[burbguy82]

Press fit we had -100F cooling and an oven a few parts still needed the press and you only got 1 chance

Yeah so the dimensions are very critical, but the hole is supposed to be smaller than the stick, so to speak. It is scary.

I made a few different tools to adjust the depth, and to remove the barrel if i messed up, which was maybe 25%.

This is of course off topic on this thread. Maybe you should make an AK thread, i will join in.

 

[chris719]

Not sure why I prefer metric on my car yet do all my PCB work in mils

Mils is a better unit for PCB work since 1 mm is big and 1 micron is tiny. You get to work in small but not fractional numbers more often.

 

[supton]

Mils is a better unit for PCB work since 1 mm is big and 1 micron is tiny. You get to work in small but not fractional numbers more often.

Yeah, that's what I tell myself too. What I've noticed so far is, anything over 1mm in size is 1.xx or 1.xxx mm, but anything under 1mm is documented in microns. Which works nicely. I'm almost used to recognizing that 75um is 3mil (the typical min space/trace I look for in any new PCB vendor) and 127um is 5mil. But no fractions involved. [yes I know how to use fractions. I prefer not to.]

But I like how 0.25mm is close enough to 10mil. I like designing on a 10mil grid and using 10mil features, and 0.25mm is close enough that it looks the same. I'm forcing myself to use mm on my side work when I can (but I basically change EDA tools doing that, change of enviroment, change in thinking is much easier).

 

[Rmay635703]

Yeah so the dimensions are very critical, but the hole is supposed to be smaller than the stick, so to speak. It is scary.

I made a few different tools to adjust the depth, and to remove the barrel if i messed up, which was maybe 25%.

This is of course off topic on this thread. Maybe you should make an AK thread, i will join in.

You don’t need to weld or thread a part with a press fit, the hole is smaller in that case so heat and cooling is needed if the fit is too extreme.

Believe me the collar or bushing will never fall off in those cases

 

[Fair enough]

Yeah, that's what I tell myself too. What I've noticed so far is, anything over 1mm in size is 1.xx or 1.xxx mm, but anything under 1mm is documented in microns. Which works nicely. I'm almost used to recognizing that 75um is 3mil (the typical min space/trace I look for in any new PCB vendor) and 127um is 5mil. But no fractions involved. [yes I know how to use fractions. I prefer not to.]

But I like how 0.25mm is close enough to 10mil. I like designing on a 10mil grid and using 10mil features, and 0.25mm is close enough that it looks the same. I'm forcing myself to use mm on my side work when I can (but I basically change EDA tools doing that, change of enviroment, change in thinking is much easier).

A lot of people don’t know the term mils is thousandths of an inch. It’s a lot easier to say mils. In a fabrication shop, like machine shop, you have to know all of it so not to have to even think about it. Very old American machine tools used metric a lot, it wasn’t a mystery.

 

[Fair enough]

I dont even understand fractional readouts on calipers, more specifically, why they are even offered.

A handle moves in .001, or at least mine does.

Point being, if the measurement you are taking is so vague, that the nearest number fractionally will do, you dont really need a caliper, you need a tape measure.

They are offered because if you can use them, senility won’t happen for awhile. It’s like a test.

 

[Cherrybomb]

Back in the 70's when America and Gerald Ford was President their was talk of the good ol U.S.A going Metric,we didn't realize how simple then it could of been.I had a car,metric and sae mix,a real P.I.A.

 

[ZeeOSix]

Just to make it more confusing ... lol.