At my new job I jun into allot of metric and an almost equal amount of standard and its a real pain in the neck to run back to the box a couple times figuring out if its metric or not. And even the other day I was working on my dads 87 chevy pickup and the fastener we always thought was 9/16 I fugured out was a 14mm becausethe 9/16 socket fit a little sloppily. So is there any way you can tell if a fastener is metric or standard? or should I just figure its metric?
Metric VS Standard fasteners
- Thread starter Matt018
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Good Question.I've noticed that most metric,were marked.The SAE have the hash marks for the grade.I just assume anything made post 1987 in vehicles is automatically metric in most cases,and then vehicles before that are hit and miss.Thats for the Gm vehicles I work on,I know other applications would be different,and Im sure there are pre 87s with metric,I just use it for the cut off.Of course Im sure there is a better,more effecient way of knowing..
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BrokewrenchLS1
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OldsRocket
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kythri
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kythri
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diesel research
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Captain Ron
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They solved this problem years ago http://www.metrinch.tv/ love my set.
StevePgh
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The best reference on anything related to fastners can be found at "BoltDepot.com". There is a link on their page for their printable reference sheets. A higher quality chart (on hardness and SAE/Metric) than the ones linked to above can be found at this link
ibedayank
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add to this... whitworth and british imperial thread
BigAl62
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In the old days when GM started using metric nuts and bolts they were blue to help identify them. Of course when they rusted or you were working on a different make you were SOL! For the longest time the domestic auto makers couldn't seem to decide whether to go to metric or stay SAE so a lot of vehicles were a mix, man did that ****! Not as bad anymore though.
Moose-LandTran
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Move to Europe and avoid American cars like the plague.
slipjointed
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I'm seriously considering moving overseas solely so I don't have to screw with two competing tool sets any more. The Metric system is just vastly superior.
I'm a proud American, but if there's one thing I'm ashamed of, it's our country's adamant refusal to move away from the imperial system.
I grew up using SAE fasteners, but whenever I do projects at home, I always use Metric fasteners when possible.
I'm a proud American, but if there's one thing I'm ashamed of, it's our country's adamant refusal to move away from the imperial system.
I grew up using SAE fasteners, but whenever I do projects at home, I always use Metric fasteners when possible.
William Payne
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Carry a metric/imperial 6 inch ruler on hand. Great for getting a rough idea of what sizes things are. If you want to know the exact size then a pair of vernier calipers are handy.
Milton Shaw
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What I found generally to be the case on GM cars. Anything that bolted to the engine was standard, anything that bolted to something else was metric. For instance, the altenator mounting bolt went to the engine, standard, the adjustment bolt went to the altenator it was metric. That was generally the way they were. But the one that gets you now is metric heads on standard thread bolts. I see a lot of stuff from china with that combination. Wish they could make up their minds. For instance a 5/16 bolt with a 12mm head, instead of 1/2 inch head.
AZ_Catskinner
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I've never found anything "superior" about metric. I find metric to be extraordinarily annoying, especially given that I work in heavy industry where thousandths of an inch still rule the roost for precision.
I also find the "decimals are better than fractions" argument to be idiotic at best. Example) 1/8" and .125" are the same damned thing. How often do we see millimeters hashed down to decimals because they aren't accurate enough? Why not just go to thousandths of an inch and be done with it? Neither system is "superior" to the other in any way.
Moose-LandTran
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I'm proud to be English/British, we invented the Imperial System and i still think metric is infinitely better.
Moose-LandTran
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Ok, firstly, you're wrong. Totally wrong. Imperial ***** and metric is simple and superior. No two ways about it.
Example:
11/32" + 5/16" + 1/8" + 1/2" + 9/16" = ???
Decimal metric, so easy to add up. Don't you get that thou is metric within imperial?
William Payne
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I live in a metric based country so metric mostly but do encounter both, I love american stuff so am familier with the imperial system and while imperial in decimals can be confusing I have taught myself how to know what a fractional measurement is in mm.
I know 1 inch is 25.4mm, so say I wanted to know what 9/16 of an inch is in metric I would just devide 25.4 by 16 then times it by 9.
I know 1 inch is 25.4mm, so say I wanted to know what 9/16 of an inch is in metric I would just devide 25.4 by 16 then times it by 9.
Moose-LandTran
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You can work out 25.4 divided by 16 then times by 9 in your head?
I just know from memory that it's 14mm.
William Payne
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I have a calculator in my toolbox, if im not near that I carry a little pocket book with all the conversion charts and things like that in it.
As far as Metric/SAE conversion for wrenching,I suppose that I just get the eye for the bolt.At first I might not know what sizing it is in metric,but I seem to catch on to identifying them fairly is.That is the common sizes though,The not so common metrics sizes I probably couldn't identify from a quick glance.Come to think about it,the only metric bolts I've encountered lately were 10,11,13,15,18,19,and 30 on a wheel hub.
AZ_Catskinner
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1-27/32" OR 46.831mm.
Metric within Imperial? I don't follow. Thousandths ARE fractions, just typically written in long form (decimals).
Here's the basic gist of the two measuring systems:
Imperial - fractional system based on units that came from an arbitrary average of British shoe sizes.
Metric - decimalized system based on arbitrary units pulled out of a French guy's ***.
Again I say that neither is superior to the other, EXCEPT for Metric's ability to be understood by people who cannot comprehend basic fractions.
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Welderguy24
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Couldn't have said it better myself, It's all personal preference. If I catch someone at work using a metric bolt when a standard could be used, I cut off his hand!
QFT right there.
Don't let the door hit you on the **** on the way out, on second thought, let it.
If you'd leave over that, just GO,
My solution to this problem is to work on vehicles that are all metric, which isn't that hard. most of the vehicles i see are metric, and maybe fewer than 10 in a year that are standard. All my metric tools are SO, and all my SAE tools are Cman.
I'm with you. My tool box is filled with metric only. My standard stuff goes into a catch all bin that I go through if I run into the rare occasion I'm working with a standard fastener.
The Dutchman
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Maybe the following scenario will shed light on, & simplify the way I personally feel, metric vs inch based. With inch based machine screws, for example, when referring to the fastener's size (nominal diameter), you've got fractions (as opposed to decimals); you've got decimals, & you also have "codes". An example of what I mean by "code" would be "#12 machine screw". This scenario is a little fragmented & arbitrary, isn't it?
Whereas, again, regarding metric machine screw sizes, it's always the # of mm in integers--no decimals (rarely, anyway). No fractions; no "codes".
It seems the latter system is much simpler, & therefore more efficient.
P.S. Another situation would be, say you want to screw a male fastener into a threaded hole & you want the length of engagement to be 2.5 X the bolt diameter. Much easier & quicker to make the calculation if you're using metric. It's the little things that add up!
Whereas, again, regarding metric machine screw sizes, it's always the # of mm in integers--no decimals (rarely, anyway). No fractions; no "codes".
It seems the latter system is much simpler, & therefore more efficient.
P.S. Another situation would be, say you want to screw a male fastener into a threaded hole & you want the length of engagement to be 2.5 X the bolt diameter. Much easier & quicker to make the calculation if you're using metric. It's the little things that add up!
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garboui
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I use both at work. I am also the one thats doing the design so its up to me what system of fastener that I want to use. I must say that 80% of the time if its not a standard sized or featured fastener my preference goes to which ever system comes with better availability. Once married to a system over availability for one particular fastener the rest will follow the same system as much as I can .
That being said I do prefer metric over imperial fasteners. Reason being, that when using sizes under 1/4" I have no clue as to what the nominal thread dia. is, WTF #sizes. Where metric is at least straight forward with this, M3 = 3mm, etc..
That being said I do prefer metric over imperial fasteners. Reason being, that when using sizes under 1/4" I have no clue as to what the nominal thread dia. is, WTF #sizes. Where metric is at least straight forward with this, M3 = 3mm, etc..
Ditchdigger
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To be able to properly drill and tap all common SAE sizes you would need a set of fraction bits a set of letter bits and a set of gauge bits. 3 sets of drill bits!
To do the same in metric you simply need one drill set.
Certain metric thread pitches are only avaliable in certain grade bolts. That way someone cannot screw in a 5.5 class bolt where a 12.9 is required. That is smart thinking.
To do the same in metric you simply need one drill set.
Certain metric thread pitches are only avaliable in certain grade bolts. That way someone cannot screw in a 5.5 class bolt where a 12.9 is required. That is smart thinking.
Metric is easy though, compared to the bastardized ways we measure precision with SAE. I mean, we use fractions of an inch for tools, but use a decimalized method for machining, in tenths, hundredths, thousandths, or ten-thousandths of an inch.
With the SI units, fractions simply aren't used. Meters (1), centimeters (.1 of meter), millimeters (.01 of meter), and micrometres (also written as micrometers, .000001 of meter).
When a cylinder is bored over .030", that's 762 micrometres, or .000762 meters, but is best written as .762mm. Likewise, a cylinder that's 4" is 101.6mm. Boring over what would be .030" would bring the size to 102.362mm.
If one designs parts to a metric standard, one can get dimensions that are nice to work with that are similar to existing SAE designs. Instead of a 4" bore, go wit ha 100mm bore. Instead of a 3.58" stroke, go with a 90mm stroke. Or, instead of smaller like this, go bigger. Go with a 105mm bore and a 95mm stroke. Now, if you need to bore over, bore over 750 micrometres (.750mm) and things would work just fine. Or, 1mm, which is just under .040 inches.
We use SAE units because we're comfortable with them. If we would be willing to deal with the discomfort of the switch, we would be able to get used to the new system within a generation or two.
We wouldn't even have to convert for everything. I'd be fine with leaving miles per hour as the standard. If we did change that too, we'd look at Km/h or alternatively written as kph. 15mph school zones become 25kph school zones. 65mph freeways become 105kph freeways. 45mph surface streets become 70 or 75kph surface streets. If anything, the presence of the third digit for kph speeds exceeding 62mph could actually be an advantage for safety, as drivers might be more sensitive to their speed with the added digit.
I would find it much easier to do all kinds of things with SI units.
dankicksass
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Nearly every time I choose a fastener for a project, it's standard. It's just so much easier to get specialty stuff in standard; if I run out of stock on chrome bolts, castleated nuts, clock-locks or other non-vanilla stuff, I can just call my local guy and they'll run it down here in a half hour. I can't get anything more interesting than a locknut in metric without waiting three days on stock. I hate waiting. That isn't to say I don't keep a good assortment of metrics around, but I don't use them unless it's factory replacement.