Mils, thou or mm? - Page 1
Forum section: electronics / projects

author: VK3DRB
author_rank: Super Contributor
timestamp: December 15, 2013, 02:15:30 am
content: Many workplaces in the electronics industry use "mils" was a verbal abbreviation for thousandths of an inch. For example, 100 mil pitch means 0.1" pitch between legs, or holes or whatever. Apparently "mils" was derived from French meaning thousand. Maybe it is just laziness... "a hundred mill pitch" is easier to say than "a two point five four mil pitch".Where I work, the mechanical engineers all use "mils" as meaning millimetres. We work closely with the mech engs to make sure our boards physically fit.But maybe all electronics engineers and technicians should say "mils" for millimetres, and "thou" for thousandths of an inch. It make a lot more sense to rid this confusion and everyone adopt the same lingo.Anyone else had similar experiences? Agree/disagree?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 15, 2013, 02:31:05 am
content: I live in bilingual Canada. In mechanical it's thous for thousands of an inch, but in others (like plastics) it's mils for thousands of an inch. Just consider yourself lucky you don't have to deal with "gauge" too!If I do a drawing in metric, I emblazon "METRIC DRAWING" across it somewhere. Can't argue with that.

author: minime72706
author_rank: Frequent Contributor
timestamp: December 15, 2013, 02:33:32 am
content: Mechanical folks, at least in the United States, usually work in inches (mils) because they kind of have to given the environment where most, if not all, tools are meant for the Imperial system.A mechanical engineer or technician or anyone who uses the utterance "mils" for millimeters is just plain wrong unless MAYBE they NEVER encounter inches anywhere.'Thou' sort of makes more sense considering we don't say "milli-inches", but I don't hear it often. I also don't think it's a very "clear" utterance - I feel like I might misunderstand someone if there was any sonic interference when they are telling me something involving 'thou'. When I hear 'mils', my brain automatically assumes a context of measurement.Millimeters is four syllables and therefore comparably ... uhh ... cumbersome. Maybe I'm biased because "microns" is what I would be more likely to hear where I used to work (unemployed). I worked on integrated circuits, so the defining features of the design would involve nanometers and microns, while when discussing die-level details with packaging (IC packaging) and mechanical folks, we would use microns or mils. They often preferred mils because it just so happens that the standard for PCB and mask design seems to be mils. They are aware of microns, but often haven't 100% memorized the conversion.

author: Lightages
author_rank: Unknown
timestamp: December 15, 2013, 02:37:03 am
content: I hate, HATE, the idiocy we have in this world still because of the short sightedness of a bunch of uneducated money grubbing "leaders". The imperial system should be banned from the face of this earth and anyone who advocates its continuation should be made to work as forced labor to make the conversion for everyone on the earth on demand 24hrs a day 365 days a year without vacation. And if they make a mistake they get no food for a week. Morons morons morons.......Oh sorry, I have no opinion on this.....Hundreds of billions of US dollars have been lost because people were afraid to lose an initial billion or so dollars during the change over. Nothing like living in a world where you never know if your airplane has enough fuel (http://en.wikipedia.org/wiki/Gimli_Glider), or if that 400 million dollar spacecraft is going to smash into the planet instead of orbiting it (http://en.wikipedia.org/wiki/Mars_Climate_Orbiter), or if the piece of equipment you are working on has imperial fasteners, or metric, or whitworth, or all three at the same time. Does your factory repair shop stock metric and inch bolts of every type just to cover the possibility that the next thing you need to repair has one or the other? Which drills and taps do you have on hand? Which wrenches and Allen keys? Is it a metric straight pipe thread or an imperial tapered? What size is that shaft and bearing? AHHHHHHHHHHHIMHO, anyone who uses stupid ambiguous "lingo" for science and engineering should be fired and sent to the metric conversion calculation farm for one year each utterance of such nonsense. Say "millimeters" or "inches" or stand before my firing squad. Idiots.....

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 15, 2013, 02:44:21 am
content: Again from bilingual Canada - the one thing the imperial distance measuring system (just inches) has over the metric system as used is that the imperial system has 1/2n fractional precision where the metric system uses 1/10n. This is far more practical in all respects; you generally want to double precision not 10x it to death. It also makes dividing by two (which you want to do 9 times out of 10 in construction and fabrication) much easier mentally. I'm sure it's why inches have held on in Canada but all other Imperial measurements have fallen into disuse.I love metrication but hate decimalization. Give me a 2n fractional metric system and we'll be done.

author: c4757p
author_rank: Super Contributor
timestamp: December 15, 2013, 02:52:20 am
content: I'll take a system with fractions in the same base as my number system, TYVM. Fractions suck ass. Leave the binary fractions to the computers.

author: IanB
author_rank: Super Contributor
timestamp: December 15, 2013, 03:05:06 am
content: Quote from: VK3DRB on December 15, 2013, 02:15:30 amYou don't have a location (flag) shown next to your avatar, so we have no idea where you work. This is vital, as the answer depends entirely on your location.Everywhere in the world except the USA engineering drawings have dimensions marked in millimetres. If you see a number like "564" on a drawing, this means 564 mm, and if someone says "the inside diameter is 564 mil" they mean it is 564 mm.In the UK and other Commonwealth countries, where Imperial measurements were used in the past, then one thousandth of an inch was "one thou". If an old-timer says "five thou" they mean 0.005 in.In the USA you have to assume all measurements are in the Imperial system unless someone explicitly says they aren't. If an engineer in the USA says "5 mils" you must assume they mean 0.005 in. If that engineer meant 5 mm, they must say "five millimeters" or you can feel free to remonstrate with them for being wrong. Whack them upside the head with a rubber mallet and tell them to wise up.So basically, the answer depends entirely on the answer to one question: "Is this inside the USA, or outside the USA?"Outside the USA, "mil" is shorthand for millimetre; inside the USA mil means one thousandth of an inch. No exceptions allowed.

author: KerryW
author_rank: Regular Contributor
timestamp: December 15, 2013, 04:14:51 am
content: He is in Australia (VK call sign).I am in the US, and I always take "mils" to mean thousandths of an inch, and "microns" to be thousandths of a millimeter.

author: TMM
author_rank: Frequent Contributor
timestamp: December 15, 2013, 05:06:17 am
content: i use 'mil' for millimeters.e.g. "i need this cut to 350 mil long"

author: calexanian
author_rank: Super Contributor
timestamp: December 15, 2013, 05:07:39 am
content: Quote from: KerryW on December 15, 2013, 04:14:51 amAgreed

author: free_electron
author_rank: Super Contributor
timestamp: December 15, 2013, 05:48:30 am
content: MILS and THOU are essentially the same and mean 1/1000 inchmetric is MM or MILLIMETERMICRON is 1/1000 MM-> MIL does NOT exist. it has no meaning. do not use this.MILS is short for "milliemes". French for thousandths as in 1/1000 not thousand. ( 1000 would be "mille" )I dont care either way. i use what is given and most convenient. Altium can handle both grid systems and swap on the fly. if you give me dimension s in MILS i enter them in mils , if given in mm i enter them in mm.The same goes for many other cad programs. Illustrator , Rhino all accept mm cm m in mils as suffix behind a numberin altium i can even type expressions as 12mm + 34 mil.this point is moot. yes it would be easier if we all were on the same system from the getgo , but we aren't. water under the bridge. move on.Blame the bloody romans. They invented the base 12 system. (Uncia means 1/12 part. inch , ounce mean 1/12 of the larger unit )It then traveled to the stiff upper lip british who carried it across the pond and populated what is now the US.So don't blame the 'mericans. the Romans invented it and the British spread it .

author: WarSim
author_rank: Frequent Contributor
timestamp: December 15, 2013, 05:53:12 am
content: You guys are hilarious.Misuse of notation has been regional for decades. Are you just noticing it now?I also got a kick out of the inference that fractions can only be used with Imperial.If there is some obscure rule about it, be very wary of equipment from Sweden.I work on stuff from all around the world. Get over it, and buy a calculator.Try translating specification from a non-technically migrated language to English.It's allot more challenging than some simple unit conversions.Sent from my iPad usingTapatalk

author: Bored@Work
author_rank: Super Contributor
timestamp: December 15, 2013, 07:25:05 am
content: Quote from: Paul Moir on December 15, 2013, 02:44:21 amHave you ever heard of the number 5? It can, for example be used in 5/10n. Upsi.QuoteWell, tell me how imperial makes dividing 0.472 in by two "much easier mentally". I'd say dividing 12 mm by two is much easier mentally.Seriously, I find this "imperial is easier to divide", precision and other "arguments" hilarious every time they are brought up. People are coming up with them not recognizing that the numbers they use in their "proofs" are always fudged.24 in is sooooo easy to divide? Yeah, sure. Now try with 7 in. Ups. You never see 7 in in these "proofs".Or take the argument that 200 miles on a road marker are so much easier than 321.9 km. Yeah, only that the 200 miles are already rounded and the place of the marker had been selected to be roughly 200 miles away from the destination. In metric land you wouldn't put 321.9 km on a marker, you would place the marker roughly 300 km from the destination and write 300 km.

author: Stonent
author_rank: Super Contributor
timestamp: December 15, 2013, 07:45:09 am
content: We used inches to put men on the moon. How many other countries have done that?So in that respect, we're the cock of the walk.Second why complain about decimalizing inches? That's better than fractional notation.Third, cars in the US are almost completely metric. I think the tires are still non-metric though.Chemistry I'm sure is almost entirely metric.So I guess all that leaves is electronics and carpentry.Carpentry doesn't bother anyone outside the US unless we're flying houses overseas. But also with carpentry you have to interface a lot with existing hardware and standards. A wall plate for a switch has been pretty much the same for the last 40 years at least

author: IanB
author_rank: Super Contributor
timestamp: December 15, 2013, 07:47:22 am
content: Quote from: Bored@Work on December 15, 2013, 07:25:05 amBut you wouldn't have 0.472 in when working in inches. The example would be 15/32 in, and then dividing it by two gives 15/64 in.

author: Stonent
author_rank: Super Contributor
timestamp: December 15, 2013, 07:54:33 am
content: Quote from: IanB on December 15, 2013, 07:47:22 amBesides, what if you're machining a part with a diameter of 4.72mm but you need to mentally convert that to radius because the cutting tool is set as the distance from center. Again no easier or harder.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 15, 2013, 09:25:11 am
content: Quote from: Bored@Work on December 15, 2013, 07:25:05 amNo no, you're wrong and your ignorance shows.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 15, 2013, 09:29:57 am
content: Nowadays I almost always use a mm grid for PCBs, as most SMD parts are metric pitch

author: tszaboo
author_rank: Super Contributor
timestamp: December 15, 2013, 09:38:51 am
content: Quote from: Stonent on December 15, 2013, 07:45:09 amSince the soviets did everything else before with their metric system that is a huge achievement. You know, they sent animals, and robots likehttp://en.wikipedia.org/wiki/Lunokhod_1

author: Psi
author_rank: Super Contributor
timestamp: December 15, 2013, 09:52:30 am
content: It's the same in the computing field. IT engineers are forever getting annoyed at people confusing bits vs byteetc. MB (megabyte) and Mb (megabit)Or even writing mb (millibit), which is ridiculous, you can't store information in fractions of bits.

author: hobbes
author_rank: Newbie
timestamp: December 15, 2013, 10:19:14 am
content: Quote from: Psi on December 15, 2013, 09:52:30 amYou can *measure* information in fraction of bits. E.g. Shannon entropy.

author: peter.mitchell
author_rank: Super Contributor
timestamp: December 15, 2013, 10:38:39 am
content: Quote from: IanB on December 15, 2013, 07:47:22 amLets instead compare measured distances instead of specified distances, because they aren't chosen based upon what seems nice in the number system, instead they are a measured value;1.277 inches vs 32.548mm1.4799 inches vs 37.59mmIt makes NO difference.Quote from: Psi on December 15, 2013, 09:52:30 amAnd don't even get me started on KiB(IEC) vs KB(JEDEC), MiB vs MB, GiB vs GB etc...

author: VK3DRB
author_rank: Super Contributor
timestamp: December 15, 2013, 11:25:18 am
content: Quote from: KerryW on December 15, 2013, 04:14:51 amI am in Melbourne. I used to work with the American IBM for many years and we universally used thou. My first job out of uni was fixing IBM card punch machines and believe me, after fixing thousands of machines, I got a "calibrated eyeball" for adjusting contact gaps - like 10 thou, 20 thou, 50 thou.Now I now design electronic circuits and write embedded code in the medical industry and we all use mm.We have developed our own own C coding standards and Altium PCB schematic/layout standards. They are a must! Our Altium standards state all alignment grids and footprints shall be in mm. To not use standards is a recipe to grey hair and annoyances. The point is, it is far more important that everyone reads from the same page than to get one's way. Anyone who has had to take over bug infested, poorly designed and badly written C code would agree.With dimensions, if everything is either in mm (or inches for our American friends), there is less chance of errors being made. Some older US-Centric datasheets only have components in inches - it is easy enough to the convert to mm. Fortunately rarely, some careless vendors use measurements without even describing the units - this can lead to mistakes for some odd-ball components.True, as someone said imperial measurements were used to get man on the moon. The communist Chinese are heading that way, and they will be using metric measurements. It is a moot point.

author: Bored@Work
author_rank: Super Contributor
timestamp: December 15, 2013, 12:09:35 pm
content: Quote from: IanB on December 15, 2013, 07:47:22 amYou are making up the numbers to make them fit. Exactly the kind of pseudo-proof I complained about.

author: c4757p
author_rank: Super Contributor
timestamp: December 15, 2013, 12:52:05 pm
content: The whole idea of thou/mil wrecks the /2 argument anyway. What's 217mil in inches? Oh look! Hey decimal point, I missed you!This "nice fractions" bullshit only works for relatively close scales. The length of my car vs the length of its windshield wipers. It sucks horribly when you must try to scale among vast differences (the distance to the next city vs. the circumference of my tires). This is where we get idiocy like 5280 feet/mile.Imperial fractions only save you from calculation when all your numbers are nice, and metric does that too! Who can't divide by two if they get to pick a nice starting point? 1000 - 500 - 250 - 125 - 62.5 - 31.25 ... Now divide 3 feet and 9 17/32king's dicksinches by two.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: December 15, 2013, 12:57:22 pm
content: Since we're using a base-10 counting system, it makes sense to base our measurements on powers of 10, not a mix of multiples of 7, 24 and whatever else imperial/customary entails. That's why miles is used for distances, and kfeet is used for altitudes. And that's why "mils" are thankfully used, instead of picas and points. Instead that unit introduced an ambiguity between different fields of work. Then look at the relationships between length, area, volume and mass in the two systems.Metric is like a puzzle where all the pieces fit, and imperial/customary is like fitting a square peg into a round hole.

author: jmaja
author_rank: Frequent Contributor
timestamp: December 15, 2013, 01:30:28 pm
content: Quote from: Stonent on December 15, 2013, 07:45:09 amAre they? It seems they decided to go metric in 1977 "AIChe goes metric":http://www.readcube.com/articles/10.1002%2Faic.690270102I had a presentation in AIChe meeting about ten years ago. Every paper had to use SI units, BUT use 8.5"x11" paper size, which I found very amusing under title "AIChe goes metric". I think 90+% of the presentation were given using Imperial units although the papers were in SI.Also the chemical handbooks I have are based on Imperial units, which makes them very difficult to use, since you must use several conversion in a row.I have extremely hard to understand why would anybody want to continue with Imperial units, which are so difficult to use and prone to errors in science and engineering.Even the very basic engineering equations like F=ma becomes difficult with Imperial units and it gets much worse when you have powers in equations. This is all due to totally rotten system for representing different scales (e.g. inches, feets, yards and miles vs. mm, m and km).

author: xrunner
author_rank: Super Contributor
timestamp: December 15, 2013, 02:06:49 pm
content: Quote from: Stonent on December 15, 2013, 07:45:09 amLOL - can you imagine going into Home Depot and asking for the 5.1 x 10.16 mm studs (2 x 4s).Just doesn't have the same ring to it.P.S.: A 2 x 4 isn't 2 x 4 inches anyway ...

author: 8086
author_rank: Super Contributor
timestamp: December 15, 2013, 02:40:41 pm
content: It's not hard to figure out units when talking in context.If we're talking PCBs, 1 mil is different enough to 1mm that you can usually work out which one someone means, even if they continually switch between them and call them both mils.Thou is just the same as mil. But I haven't encountered anyone using it IRL.I generally use mm for everything.

author: Neilm
author_rank: Super Contributor
timestamp: December 15, 2013, 03:00:33 pm
content: I tend to use mm for board design at work as I have to worry about clearances to meet international standards and these are all worked out in mm.

author: deth502
author_rank: Frequent Contributor
timestamp: December 15, 2013, 03:54:27 pm
content: Quote from: xrunner on December 15, 2013, 02:06:49 pmit is, actually. thats why they call it a 2x4. when they rough cut lumber it is 2"x 4". then it is kiln dried, which shrinks it a little. if you buy a kiln dried 2x4 from a sawmill, your going to get something right around 2"x4" +0/-1/8". the lumber is then processes, planed down, corners rounded, and shipped to your home depot. after planing them smooth they are approx 1 1/2" x 3 1/2". when you work with rough cut lumber you will learn that 2x4's are 2x4, 1x is 1", and 5/4 is 5/4"now, when i hear "mils" i think milradians, so fuck all 'a yall.

author: rolycat
author_rank: Super Contributor
timestamp: December 15, 2013, 04:02:36 pm
content: Quote from: xrunner on December 15, 2013, 02:06:49 pmYou'd get very funny looks inanycountry if you asked for 5.1 x 10.16 mm studs. That would be 0.2 by 0.4 inches.QuoteIndeed. However, if you're buying studwork timber in a country like the UK you would likely ask for 38 x 89 mm, whichis38 x 89 millimetres.You might very well pronounce 'mm' as 'mil'...When most people buy timber they don't really care what it looked like when being rough cut in the sawmill

author: xrunner
author_rank: Super Contributor
timestamp: December 15, 2013, 04:14:32 pm
content: Quote from: rolycat on December 15, 2013, 04:02:36 pmLOL, yea didn't have enough coffee this morning.

author: KerryW
author_rank: Regular Contributor
timestamp: December 15, 2013, 04:20:21 pm
content: QuoteAre you building a doll house? (a 2x4 is ~5x10 CM, not MM)Both systems are arbitrary, and whether you are talking .472" or 4.72mm, you need to measure using appropriate instruments.The scaling argument doesn't carry much weight, either. I have never had to measure mile distances to the inch, or kilometer distances to the mm. But I have a calculator, should I ever need to.It can be frustrating to compare, for example, two motors, one with torque listed in oz-in and the other in N-cm. How hard is it to provide both on a spec sheet?On the other hand, current flow is NOT arbitrary. Electrons are what is flowing, and they flow from negative to positive. They go from the emitter to the collector, NOT from the collector to the emitter. They go from the source to the drain. Now, how many people who think I should trade one arbitrary system for another would be willing to trade their demonstrably incorrect system ("current flow") for a correct one? (I learned electron flow in the US NAVY)

author: c4757p
author_rank: Super Contributor
timestamp: December 15, 2013, 04:21:39 pm
content: Quote from: deth502 on December 15, 2013, 03:54:27 pmWhen I buy a pound of flour at the grocery store, I'm not the least bit interested in how much the raw wheat weighed.

author: free_electron
author_rank: Super Contributor
timestamp: December 15, 2013, 04:32:54 pm
content: Quote from: xrunner on December 15, 2013, 02:06:49 pmI found that out a couple of years ago. I asked what the common lumber size were. 2x4 4x4 etc. i worked out my exact dimensions thinking "this is easy, it's all standardized."I come home and nothing fits. WTF ? So i doublecheck. Go back to store andco plain about them giving me wrong stuff. I asked 2x4 and its clearly waaaaay off. Answer: no it is correct 2x4 doesnt mean 2 inch by 4 inchGhaaaaaa !

author: minime72706
author_rank: Frequent Contributor
timestamp: December 15, 2013, 04:43:05 pm
content: This thread exploded a bit, but what I have to say about people who bitch about the US continuing to use the Imperial system is that it would be unimaginably expensive to retrain people and retool machines. Through that process I bet you cash money that mistakes will be made and both money and lives will be lost. I wish we'd convert as much as anyone, but I just don't see it happening. It sucks ...

author: rolycat
author_rank: Super Contributor
timestamp: December 15, 2013, 05:04:38 pm
content: Quote from: minime72706 on December 15, 2013, 04:43:05 pmIt really wouldn't. Pretty well every other country in the world has managed it without going bust or killing half their citizens. As was alluded to above, the UK largely soft-converted its building industry, so nominal 2 x 4 timber became 38 x 89 mm and half-inch plasterboard (drywall) became 13mm without any actual changes in their dimensions.The only reason the US has gotten away with it until now is that you are relatively isolated and insular, and you are/were big enough to force countries importing US goods to accept your non-standard standards in a number of industries.The British Empire did much the same thing while it had the power - heck, why do you think they are called Imperial measurements?

author: MrsR
author_rank: Regular Contributor
timestamp: December 15, 2013, 05:07:37 pm
content: Back in the early 1980s we designed an aircraft.Now being good law abiding Australians (the Gov. made it law that only Metric could be used ) we struggled and learned Metric and sent the Aerodynamic and structural calculations with the drawings all in Metric into CASA. A short time later the package came back with a query "WHAT THE HELL IS THIS RUBBISH" do it in Imperial and re-send. The reason for this is that a decimal point in the wrong place is easy to miss in metric and can change an amount by 10, 100, 1000 or even a million. newton load over a sq. meter or was that 1 newton per sq. mm.As for measurements for Engineering drawings Mills means metric and thou. is imperial and I much prefer thou on my drawings than parts of MM.When using CAD we use decimal and put Millimeters or Imperial and can put a denominator .1520" or .1520MM NOTE: When I wrote .1520" Google came on screen with 3.8608I'm around the twist already??? Rachael

author: KerryW
author_rank: Regular Contributor
timestamp: December 15, 2013, 05:08:56 pm
content: Quote from: minime72706 on December 15, 2013, 04:43:05 pmI am reasonably comfortable with both systems, but I typically use inches. My lathe/mill has inch leadscrews (20 TPI), but I built a DRO that displays inch or mm. I have an X-Y stage with CNC steppers, but I didn't bother to add metric, as my CAD program will provide data in inches. My dial indicators, calipers and micrometer are all in inches.I don't think metric will become popular in this country until you can buy metric hardware in a local hardware store. Drills, taps, screws, nuts, etc have to be ordered.

author: N2IXK
author_rank: Frequent Contributor
timestamp: December 15, 2013, 05:11:28 pm
content: US dimension lumber originally WAS the full nominal dimensions. This changed somewhere in the 1920s or 1930s, when sawmills became more automated and standardized. My house was built around 1905, and all the original wall studs are a full 2" x 4", whereas a modern "2 x 4" is ~ 1.5" x 3.5 ". Sometimes calls for some creativity (and strips of plywood as shims) when interfacing between old and new construction.Quite often, I do some machining of metal and plastic parts for various projects. The manual dials on the milling machine and lathe are all calibrated in thousandths of an inch. If I have to work in metric, the digital readout that has been added to the machines can be set to read in decimal inches or mm. But the machines themselves were designed for the US standards, and most of the collets, tooling, and stock we work with is also manufactured in imperial sizes.This was probably the real reason for the reluctance to convert completely to metric here in the US. Perfectly serviceable capital equipment would need to be scrapped, entire supply chains retooled, etc. A huge expense, and a waste of perfectly usable resources, with no immediately apparent payoff. Given the tendency of businesses and politicians to not think past the next quarterly report or election cycle, the result isn't exactly a surprise.

author: Bored@Work
author_rank: Super Contributor
timestamp: December 15, 2013, 05:12:13 pm
content: Quote from: MrsR on December 15, 2013, 05:07:37 pmAnd the next argument is pulled out of the arse. Easy to miss wrong decimal points in metric? You imperial fanatics know no shame. As if a wrong decimal point has no effect in imperial rubbish.Quote from: N2IXK on December 15, 2013, 05:11:28 pmAnd the next one ...Nothing has to change, nothing retooled, except that you start with new stickers to put on your wares, providing information in metric units.

author: Rufus
author_rank: Super Contributor
timestamp: December 15, 2013, 05:18:54 pm
content: Quote from: Bored@Work on December 15, 2013, 07:25:05 amThe only reason we use a decimal system is we evolved with 10 fingers.Decimal lets you easily halve and fifth, Duodecimal lets you easily halve, third, quarter, and sixth.If we could start over again and choose a number base for general use it would be duodecimal or possibly hex.

author: WBB
author_rank: Regular Contributor
timestamp: December 15, 2013, 05:30:31 pm
content: Quote from: free_electron on December 15, 2013, 04:32:54 pmIt wasn't a 2 x 4 when it was growing in the forest and it isn't when you buy it. But at some point in between it was in the neighborhood of 2" x 4" so that's what we get. Granted it's simpler to say than the actual dimensions and we all know that 2 x 4s aren't really 2" x 4". The problem is that before we all knew this information each of us had to learn it. Some had an easier and cheaper lesson than others.Back on topic. For a lot of the things the average person needs to physically measure, a millimeter provides adequate resolution. Obviously that doesn't apply to everyone but is more than enough for many of us. If I want to measure an opening in an enclosure, an enclosure, or even lumber, millimeter resolution is often more than adequate. To measure an enclosure, or an opening in said enclosure, I can use a cheap ruler than often has both inch and metric markings. I can choose to have my whole number resolution be either 1" or 1mm. I'll take the latter.I am definitely in the camp that wishes the US would switch. I agree that it would be expensive but I'm not so sure it would be as expensive as we might think. Most manufacturing equipment is computer controlled and I would think those computers could handle conversions in software quite well. I realize that wouldn't work in all instances but probably would for many. It probably already happens in the reverse anyway. Changing standardized things (lumber for example) would suck for a while. But then again, just because our new 2 x 4s would likely be called 5 x 10s doesn't mean they actually have to be within a couple millimeters of those dimensions.

author: WBB
author_rank: Regular Contributor
timestamp: December 15, 2013, 05:34:25 pm
content: Quote from: Bored@Work on December 15, 2013, 05:12:13 pmAt least with the metric system, a misplaced decimal point might well be a large enough error that someone would actually notice there was a error and correct it.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 15, 2013, 05:35:10 pm
content: Quote from: Bored@Work on December 15, 2013, 05:12:13 pmExactly. A 2x4 would just be a 38x89 or more likely still a 2x4. In this here metric country it is still ato fire bom(two four beam). As for weird things happening to timber sizes: here in DK a 5" board has shrunk from 13 cm to 12.5 cm because of a switch fromtommerto inches.

author: MrsR
author_rank: Regular Contributor
timestamp: December 15, 2013, 06:27:49 pm
content: Quote from: Bored@Work on December 15, 2013, 05:12:13 pmHOPE YOUR REAR END IS HURTING.You can not just put new metric stickers on all the lead screws etc would have to be changed.Work it out.Rachael

author: jmaja
author_rank: Frequent Contributor
timestamp: December 15, 2013, 06:45:47 pm
content: Quote from: MrsR on December 15, 2013, 05:07:37 pmThat is completely wrong! M is used for "mega", which means 1e6 and meter is not M it is m. Mm=1e9*mm and MM is nothing in SI units. The same prefixes are used for every unit and this is what makes the SI system so easy to use.

author: MatCat
author_rank: Frequent Contributor
timestamp: December 15, 2013, 07:09:59 pm
content: Everyone who is arguing needs to watch this!Now as an American, I find myself using both systems about equally.

author: tszaboo
author_rank: Super Contributor
timestamp: December 15, 2013, 08:06:07 pm
content: Quote from: minime72706 on December 15, 2013, 04:43:05 pmYes, it is easyer to convince people to make another war to boost economy than convince them to use a different UoM just to be compatible with the other 200 +/- 5 countries in the world.All in favor the imperial system: please give us the equivalent to: weber, tesla, oersted.Also, express the boltzmann's constant or the average distance between C atoms in the diamond in the imperial system.

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: December 15, 2013, 08:47:39 pm
content: I remember a long, long, long oh so long time ago, going into the mechanical workshop where i worked and asking the most stupidest of questions;How many thou in an inch i asked; clearly the brain wasn't working at that moment in time,The answer came in a loud voice from across the room.fuckin hundreds of em ( please excuse the language, it was the answer )I'll never forget that moment ever

author: MatCat
author_rank: Frequent Contributor
timestamp: December 15, 2013, 08:48:26 pm
content: You also have to account for the fact that the average lay person in America is quite comfortable and familiar with imperial, I remember when I was in school in the 90s and they where talking about switching to metric EVERYONE hated the idea, I know people now that do technical jobs and have no idea how to use metric, it's all 'greek' to them, so it's really not that simple to just switch. If you don't like imperial don't use it, that's how I look at it.

author: N2IXK
author_rank: Frequent Contributor
timestamp: December 15, 2013, 09:36:33 pm
content: That is really the key if you live in the US. You need to be comfortable with the imperial system just to get by in everyday life. Like it or not, logical and consistent or not, it isn't going anywhere anytime soon. If you work in a scientific field, you will be working almost exclusively with metric/SI units, as it should be.If you work in engineering, that's where the problems arise--because your designs have to get translated into physical reality using components, materials, and processes that that could be specified in either system. Consider a PC board containing a mix of SMD (metric) and through-hole (imperial) components...

author: abyrvalg
author_rank: Frequent Contributor
timestamp: December 15, 2013, 10:38:10 pm
content: USSR was producing metric through-hole components like DIP ICs with 2.5mm (not 2.54) pitch. Replacing some 14-pin "commie" K155xxx with "western" 74xx wasn't a problem, but something bigger like 40-pin Z80 clone/original required violent pins bending

author: WarSim
author_rank: Frequent Contributor
timestamp: December 16, 2013, 03:59:12 am
content: Quote from: abyrvalg on December 15, 2013, 10:38:10 pmLOL. What kind of board designer would make pin spacing of 2.54mm instead of 2.5mm for a 40pin 2.5mm pitch chip.Sent from my iPad usingTapatalk

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: December 16, 2013, 04:35:48 am
content: Quote from: N2IXK on December 15, 2013, 09:36:33 pmAll SMD devices are not based on metric measurements. It's important to design footprints in the native units; the rounding error in conversion can become significant over the space of 10 or more pads.

author: jmaja
author_rank: Frequent Contributor
timestamp: December 16, 2013, 06:58:13 am
content: Quote from: Jon Chandler on December 16, 2013, 04:35:48 amWhy? One inch is exactly 25.4 mm. Just take care to use enough decimals.

author: cravenhaven
author_rank: Contributor
timestamp: December 16, 2013, 09:41:31 am
content: Its obviously not that easy for some people to use the metric system. Have a look at this question on a Q&A forum at Officeworks for a monitor stand:Is there any chances of having the dimesions in centimeters instead of millimeters? Also could I rest a small LCD TV on it??

author: Rufus
author_rank: Super Contributor
timestamp: December 16, 2013, 10:18:37 am
content: Quote from: jmaja on December 16, 2013, 06:58:13 amWhile 1mm is only approximately0.039370078740157480314960629921259842519685039370078740157480314960629921259842519685039370078740 inches

author: rolycat
author_rank: Super Contributor
timestamp: December 16, 2013, 10:39:39 am
content: Quote from: Rufus on December 16, 2013, 10:18:37 amGiven that the absolute uncertainty in the definition of the standard metre is 0.1 nm, do you really feel that 'approximately' is the appropriate word for this figure?

author: WarSim
author_rank: Frequent Contributor
timestamp: December 16, 2013, 03:44:18 pm
content: And now the post diverts to another obserdium.Is a discussion on the subjects of uncertainty, comparative ratios and practical resolution really required?The imperial to metric conversion is obviously rooted in other reasons than numbering system capabilities.This is a subject for Dr Phil's site.Sent from my iPad usingTapatalk

author: Sigmoid
author_rank: Frequent Contributor
timestamp: December 16, 2013, 05:57:15 pm
content: Lol. Well, for one, I don't think it makes sense to argue about why people are using one system or the other.It's like bitching about why people in Brazil speak Portuguese, when in fact Spanish is a much better language, and it would make a lot of sense only having to learn Spanish and being understood throughout South America. Oh and let's not forget that Spain is a much larger country than Portugal.Yes, if Brazilians spoke Spanish, it would be so much easier for everyone else, but come on...(If they spoke English, it would be even better. In fact, everyone should speak English, for that matter.)As for thous vs. mils, I always say "thous", because "mils" is too confusable with millimeters. But I guess thous are here to stay. I'm pretty sure they use them for PCB design even in Germany.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 16, 2013, 06:21:31 pm
content: Quote from: Sigmoid on December 16, 2013, 05:57:15 pmI can't really imaginethouin a German sentence. Any Germans who can comment on the use of mils/thous in Germany?

author: pmbrunelle
author_rank: Regular Contributor
timestamp: December 17, 2013, 02:43:45 am
content: Quote from: Jon Chandler on December 16, 2013, 04:35:48 amSI native units > Imperial native units > SI soft converted units (with errors, sometimes)Soft conversion just leads to confusion and uncertainty. For the 2x4/ 38x89 lumber case, I wouldn't even be know what I'm buying in that case... I don't even trust datasheet footprints half the time. Unless I see numbers like 6.35 mm, for example.The SI system is good, but soft conversion h*ll is worse.Unless everything becomes natively SI, I'll keep the use of inches where appropriate.The units themselves don't matter. What matters is being standardized, and being unambiguous.

author: VK3DRB
author_rank: Super Contributor
timestamp: December 17, 2013, 12:41:48 pm
content: Quote from: pmbrunelle on December 17, 2013, 02:43:45 am

author: rolycat
author_rank: Super Contributor
timestamp: December 17, 2013, 02:54:51 pm
content: Quote from: pmbrunelle on December 17, 2013, 02:43:45 amYou're from North America, and are consequently natively confused and uncertain about mensuration.I suspect 2x4 timber that is really nothing of the sort originated in England, but we got better...

author: IanB
author_rank: Super Contributor
timestamp: December 17, 2013, 04:26:58 pm
content: Quote from: rolycat on December 17, 2013, 02:54:51 pmThe really confusing thing is that a 2x4 in England is a 4x2 in the USA. How the Americans managed to get both dimensions off by a factor of 2 is beyond me...

author: free_electron
author_rank: Super Contributor
timestamp: December 17, 2013, 09:14:35 pm
content: Quote from: WarSim on December 16, 2013, 03:59:12 amtake a look at those screw terminal blocks. they exist with 5mm spacing and with 5.08mm spacing.... and you always got the wrong ones in stock !

author: Tinkerer
author_rank: Frequent Contributor
timestamp: December 17, 2013, 11:59:02 pm
content: For god sakes people, just learn both, instead of arguing about it.I use whatever units fit my needs at the time(for personal projects). If its easier to use inches, I use those, if its easier to use metric, I use that. I find that many items contain both metric and imperial measurements. At work, I am not required to measure anything in length units but I always pronounce the entire word millimeter etc anyway so its clear.US cars still have both km per hour and miles per hour on them.I also a roman numeral clock in my kitchen in .

author: Corporate666
author_rank: Unknown
timestamp: December 18, 2013, 12:42:14 am
content: Quote from: minime72706 on December 15, 2013, 02:33:32 amInteresting because my experience is quite different.I find that electronics guys are one of the few holdout groups who use "mils" to mean "thousandths of an inch". Mechanical guys universally use "thou". I have never heard the use of "mil" to mean 0.001". I have heard some mechanical guys abbreviate "mils" to mean millimeters. Interestingly, I am on some machining forums and there are occasionally guys who come along looking to get parts made, and when they talk in mils, they are almost universally misunderstood to be talking about millimeters, so when you say mechanical folks work in mils (inches), it must be either a regional thing or confined to a specific area like plastics or sheet metal or something like that?The super precision guys talk in microns

author: arvidj
author_rank: Contributor
timestamp: December 18, 2013, 03:57:23 am
content: Quote from: Corporate666 on December 18, 2013, 12:42:14 amOr "tenth's" ... which is .0001 ... ten thousandth of an inch. Very confusing the first time I saw it. "Just remove another couple of tenth's and it will fit fine", at which point I began looking for the emery paper.

author: mrflibble
author_rank: Super Contributor
timestamp: December 23, 2013, 03:04:29 am
content: Quote from: Rufus on December 16, 2013, 10:18:37 amWe're cherry picking rational numbers now to make some sort of obscure point? Oh oh oh, can I join?Somethingsomething, while 1 inch is only approximately 0.0833333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333 feet, therefore <obscure_point>.

author: Rufus
author_rank: Super Contributor
timestamp: December 23, 2013, 03:42:44 am
content: Quote from: mrflibble on December 23, 2013, 03:04:29 amI was just making the point that when you convert 1mm to inches and add 25.4 of them together converting back to mm will not give you exactly 25.4. 25.4 mm being exactly 1 inch does not prevent accumulation of rounding errors.

author: mrflibble
author_rank: Super Contributor
timestamp: December 23, 2013, 03:53:21 am
content: Quote from: Rufus on December 23, 2013, 03:42:44 amFor cases where that sort truly is the biggest concern I find that working with said rational numbers in aproper toolworks just fine. Also, 5/127.For all other cases you just use proper precisions such thataccumulated error<your tolerance of the day. Just like you would in all other engineering calculations, sooo ...

author: Rufus
author_rank: Super Contributor
timestamp: December 23, 2013, 04:45:05 am
content: Quote from: mrflibble on December 23, 2013, 03:53:21 amAnd when for example in a PCB package you step a pad for a 100 way edge connector your tolerance of the day suddenly needs to be 100 times higher than was for placing anything else. You are stuck with the precision the package gives you. Regardless of your glib comments it is a real and real world issue.

author: mrflibble
author_rank: Super Contributor
timestamp: December 23, 2013, 06:04:56 am
content: Quote from: Rufus on December 23, 2013, 04:45:05 amThis is indeed a good example of where having metric and imperical side by side is annoying. But while I do find it annoying, so far both Eagle and Altium seem to be able to spit out manufacturable gerbers just fine.QuoteAnd regardless of my glib comments real world solutions exist for this real word issue. For your PCB example in the form of software written to take into account the domain problem of "must work with both metric and imperical because welcome to PCB world".So let's reach a world wide compromise, let's all use English and metric.Or we could all use German and metric (essentially the same end result, except we get to drink more beer and shit doesn't break as often). Or Spanish and metric (shit would break more often again ... tomorrow). Or Mandarin and metric. And thank Thor the Chinese at least use metric and SI as primary standard by law.(and of course they accept imperial, they want your moneys)

author: ElektroQuark
author_rank: Unknown
timestamp: December 23, 2013, 09:07:41 am
content: QuoteI didn't know JBC tools where that bad. Or all the machinery made in the Basque Country I'm from.

author: G0HZU
author_rank: Super Contributor
timestamp: December 23, 2013, 11:25:02 am
content: Quote from: Tinkerer on December 17, 2013, 11:59:02 pmAgreed.For PCB design I always work in thou (of an inch) because that is how PCBs are always designed at my place of work. We use Mentor for PCB design but despite the huge cost/complexity/capability of this SW we choose to use the traditional thou of an inch system for PCB design.For PCB design it's more convenient and intuitive to work in thou and also the PCB material uses the imperial system to quantify dimensions. It's far more intuitive to look at track widths and etching tolerances in thou and this is the lingo still used by the big PCB manufacturers.To an outsider it probably seems a bit quaint to still use the imperial system for PCB design. However, we usually use the metric system to design the PCB board size and mounting holes (because our 3D CAD uses metric) but once the PCB design starts in terms of component placement and tracking it is all in thou of an inch and I wouldn't want it any other wayFor pretty much everything else I prefer to use the metric system.

author: Dave
author_rank: Super Contributor
timestamp: December 23, 2013, 02:17:37 pm
content: I used to use mils for trace widths. Kept switching between metric and imperial, because I had hole sizes in metric (my drill bits are all in metric), awful task.No more! I use millimeters and microns for everything now. Imperial system is outdated, obsolete, and downright ridiculous - and should be treated as such.

author: G0HZU
author_rank: Super Contributor
timestamp: December 23, 2013, 04:09:10 pm
content: It isn't obsolete or ridiculous because the manufacturers of PCB materials still use imperial measures to size and grade their PCBs.eg dielectric thickness and copper weight are still imperial. I work as an RF designer in a large company and the PCB material supplier, the PCB draughtsman who designs my board for me and the company that manufactures the PCB all still work in thou. I don't ask for them to do this and I hope they don't change.Also, most through hole and SMD parts are sized in imperial and not metric.eg 1206, 0805, 0603 are all imperial sizes for SMD parts and these part descriptions are not obsolete.The key to success is to use whichever system works best for a specific task. Metric isn't always best. For example, could you tell me the approx size for an 1812 packaged SMD part in metric without looking it up? It's much easier if you use imperial. The clue is in the name of the part

author: Monkeh
author_rank: Super Contributor
timestamp: December 23, 2013, 04:47:38 pm
content: Quote from: G0HZU on December 23, 2013, 04:09:10 pmYou mean a 4532? Sorry to burst your bubble, but the imperial sizes are an approximation to suit imperial users.

author: mrflibble
author_rank: Super Contributor
timestamp: December 23, 2013, 05:33:03 pm
content: Quote from: Monkeh on December 23, 2013, 04:47:38 pmNot only that, but I distinctly recall PCB stackups being specified in micrometers by several Chinese pcb manufacturers. And ditto for copper thickness. Don't say 1 wizard of Oz, but say 35 micrometer. Don't say 2 wizards of Oz, but say 70 micrometer. Not all that difficult really. With the added bonus that 70 micrometer is anactual length, as opposed to a non-SI-weight-which-you-can-convert-to-volume-by-dividing-by-copper-density-and-then-you-divide-by-unit-area-to-get-thickness-ohmygoodnessthisisintuitive!!And bga grids tend to be in mm's more often. So it might take a while longer, but with a bit of luck we'll be rid of an yet another arbitrary system that seemed like a good idea at the time but has outlived it's usefulness. Should slowly die out with it's users.

author: underwurlde
author_rank: Newbie
timestamp: December 23, 2013, 07:57:05 pm
content: For me, mil aka thou for PCB component footprints or mm if component uses mm spacing. Depends on datasheet really.mm for everything else.0805, 0402, 1206. Imperial? thought that was metric? Divide number pairs by 4 to get mm X Y dimensions. Maybe I've been wrong all these years....Being of a certain age, my brain can 'think' in both metric or imperial, makes no odds to me and both have their place in the world although I wish that all nuts and bolts were just metric tbh.A

author: Monkeh
author_rank: Super Contributor
timestamp: December 23, 2013, 08:04:29 pm
content: Quote from: underwurlde on December 23, 2013, 07:57:05 pmWrong, although a close(ish) approximation.

author: underwurlde
author_rank: Newbie
timestamp: December 23, 2013, 08:09:40 pm
content: F-me sideways! one can really learn something new everyday!A

author: G0HZU
author_rank: Super Contributor
timestamp: December 23, 2013, 09:30:58 pm
content: But my point is valid. The commonly used size designators are imperial? Many people don't realise the size is in the case descriptorThe commonest ones are below:0805 is 0.08" x 0.05"0603 is 0.06" x 0.03"0402 is 0.04" x 0.02"If you know the case description then you know the approx size.I don't know or care (yet) what the metric equivalent of 0603 is because everybody we deal with at work (suppliers, buyers, assemblers etc etc) use 0603.Rogers supply RF PCB material in thou thickness ratings and have done for decades. People can order in metric if they like to approximate to 3 decimal places but common sizes are 60, 32, 20 and 16 thou thick in 0.5 or 1 oz copper weight.None of this stuff is obsolete (yet). People can rant and ridicule all they like but the best way to deal with the current situation is to swap between imperial and metric systems if one task is more suited to one system than the other.That's what everybody does at my place of work and (IMHO) the correct thing to ridicule is the person who defiantly chooses to use one system exclusively and who mocks the other.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 24, 2013, 01:27:58 pm
content: Quote from: G0HZU on December 23, 2013, 09:30:58 pmThe ridicule really belongs with the people who made JEDEC decide on even allowing the use of anything but the metric designators for SMD parts.

author: tszaboo
author_rank: Super Contributor
timestamp: December 31, 2013, 03:33:26 pm
content: Quote from: G0HZU on December 23, 2013, 09:30:58 pmTell me then why Vishay, an american manufacturer defines the component size in metric:http://www.vishay.com/doc?20036Or why the SMD parts are using 0.65 0.5 pitch, and TI in every new datasheet specifies component size only in metric. Or why doesn't our PCB manufacturer's have any imperial tool? And after exporting a gerber file, everything is in metric? Not to mention, everything just fits better on a PCB when you use metric. I actually got headache, if I have to work with an imperial designed board in Altium. Nothing is on grid and the components are all over the place.

author: G0HZU
author_rank: Super Contributor
timestamp: December 31, 2013, 03:55:18 pm
content: Quote from: NANDBlog on December 31, 2013, 03:33:26 pmjeez this is hard work...I don't care (and it isn't relevant) if VISHAY quote their caps in metric or if they choose to measure them in terms of how many ants eggs long or wide they are.0603 is a package descriptor measured in inches.

author: Monkeh
author_rank: Super Contributor
timestamp: December 31, 2013, 04:23:11 pm
content: Quote from: G0HZU on December 31, 2013, 03:55:18 pmYes, and it's an approximation of the industry standard, metric, 1608 descriptor.

author: Rufus
author_rank: Super Contributor
timestamp: December 31, 2013, 04:29:45 pm
content: Quote from: G0HZU on December 31, 2013, 03:55:18 pmAnd 1608 is a descriptor for the same package measured in 'metric'. Being more familiar with one doesn't make the other one wrong any more than being more familiar with inches makes mm wrong.Here is my crib sheet for some common ones.01005 (0402 metric)0201 (0603 metric)0402 (1005 metric)0603 (1608 metric)0805 (2012 metric)1206 (3216 metric)1210 (3225 metric)1806 (4516 metric)1812 (4532 metric)2010 (5025 metric)2512 (6432 metric)Quote from: NANDBlog on December 31, 2013, 03:33:26 pmThat is mostly crap. I have yet to find a PCB manufacture who can't accept imperial gerber and drill files. Things do not 'just fit better' when using metric. There are plenty of packages with imperial pin spacing and Altium for example uses an imperial internal representation which means the board I am currently working on has some package pins on a 0.90001mm pitch. The board is full of small rounding errors for items placed on a metric grid and it occasionally causes grief with comparisons. That isn't a criticism of metric or imperial systems, it is just historically the way it is, Altium should have chosen a better internal representation unit to accommodate both.

author: G0HZU
author_rank: Super Contributor
timestamp: December 31, 2013, 04:31:21 pm
content: Quote from: Monkeh on December 31, 2013, 04:23:11 pmBut the point is that manufacturers still sell the resistors as 0603 and use 0603 in their long manufacturers part number.QuoteGo on the Farnell website and try and see how many manufacturers still use the imperial system for SMD parts.Even VISHAY use 0603 in their long part number. See below. Look on their datasheet and they still use imperial descriptors in the part number (NOT METRIC) Can you explain why they still do this?http://uk.farnell.com/vishay-draloric/crcw0603120rfkea/resistor-0603-120r-1/dp/1652832RLIf the manufacturers, suppliers etc, etc used the metric descriptor then my point would not be valid. But they DO still use imperial descriptors.Manufacturer Part No: CRCW0603120RFKEA

author: Monkeh
author_rank: Super Contributor
timestamp: December 31, 2013, 04:33:58 pm
content: Quote from: G0HZU on December 31, 2013, 04:31:21 pmBecause people would get confused the world over because one single country decided to stick with Imperial and drove the industry this way.

author: G0HZU
author_rank: Super Contributor
timestamp: December 31, 2013, 04:43:12 pm
content: QuoteI agree and I'm making the point that most sectors of the industry still use the imperial system for describing SMD parts. So the imperial system isn't obsolete (yet)I'd also like to clarify that I'm not trying to say one is better than the other. But sometimes it is more convenient or intuitive to use one over the other.QuoteYes, for PCB design it is still quite common to use thou of an inch and we use some of the main PCB manufacturers like Exception and Graphic and they are both quite happy to work in metric or imperial when discussing PCB issues with us.eg they can quote us the accurate trace width for a 50 ohm microstrip trace or a buried stripline trace for a particular multilayer PCB layer stack. They usually quote us in thou of an inch but they also do metric just as easily.

author: Monkeh
author_rank: Super Contributor
timestamp: December 31, 2013, 04:45:22 pm
content: Quote from: G0HZU on December 31, 2013, 04:43:12 pmIt's just incredibly annoying that we're still stuck mixing them. Every new specification is metric, so why on earth do people persist in using imperial designations formetric specifications?

author: tszaboo
author_rank: Super Contributor
timestamp: January 01, 2014, 03:27:09 pm
content: Quote from: Rufus on December 31, 2013, 04:29:45 pmThe distance between a 0603 pads is 0.5mm you can put a 0.3mm track through it using 0.2mm spacing. Once, try to route a 6 row BGA which has 0.5mm pitch using imperial.IPC stated, that everything PCB related should be using 0.05mm grid.JEDEC is based on metric, DIN is based on metric, IEC, EIAJ...Even the USA signed the Metric Conversion Act of 1975BTW I'm not sure which version of altium you are using, but mine uses 1um as the smallest grid.

author: Rufus
author_rank: Super Contributor
timestamp: January 01, 2014, 04:52:08 pm
content: Quote from: NANDBlog on January 01, 2014, 03:27:09 pmOr the distance between 0603 pads is 20mil you can put a 12mil track through it using 4mil spacing - completely irrelevant.Quote from: NANDBlog on January 01, 2014, 03:27:09 pmI can measure the distance between two pads and get the attached showing 0.01um resolution. The internal representation is micro inches and as far as I know has been since the first Win32 version. Note that 35.434mil is actually 0.90002mm anyway and of course the pads were placed in the library editor on a metric grid which gets messed up a bit by the internal representation and messed up again when you locate and move the part on a board. No one cares about 0.01um on a PCB but it can mess up comparison and queries. At one time the hole size editor was screwed up not reporting pads which had hole sizes very close to others. When you changed the hole size of the ones that did show it changed the close ones as well and suddenly they all showed.In Altium metric causes not avoids problems because they made a poor choice of internal representation.

author: WarSim
author_rank: Frequent Contributor
timestamp: January 05, 2014, 05:32:00 pm
content: Quote from: G0HZU on December 31, 2013, 03:55:18 pmBecause the metric users have shown adaptability and are unlikely confused or scared off by imperial numbers.On the other hand imperial only users have proven to be opinionated about their chosen measurement system and are likely to avoid a metric denoted product.It is all about marketing and maximizing their market share.Have you not heard, "the squeaky gets the grease". Squeak away, it is your right.Hopefully someday the squeakers will become a small enough minority and the USA suppliers can stop using their two system compromise.Just a though maybe USA makers are using the two system excuse to explain their dimensional inaccuracies..Thanks for the entertaining thread.I find it really funny when people complain that they can't measure a spec of +-1 to the accuracy of +- 0.001.Equally entertaining is how a tiny unit errors are allowed to become cumulative by proclaimed professionals, and then complain about them.Sent from my iPad usingTapatalk

author: Unknown
author_rank: Unknown
timestamp: January 05, 2014, 06:53:25 pm
content: Quote from: rolycat on December 15, 2013, 05:04:38 pm12.5mm.Quote from: IanB on December 17, 2013, 04:26:58 pmOther way around.Quote from: WarSim on January 05, 2014, 05:32:00 pmNot one person gives a shit.ETA: Just thinking about the time etc... Complete mess, random selection of base 7/12/29/30/31/60.Decimal time FTW.

author: G0HZU
author_rank: Super Contributor
timestamp: January 06, 2014, 12:43:37 am
content: Quote from: WarSim on January 05, 2014, 05:32:00 pmIf you are going to quote me then please try and quote something that came from me and not someone else?.Sent from my PC using my fingers and a keyboard

author: WarSim
author_rank: Frequent Contributor
timestamp: January 06, 2014, 04:49:12 am
content: Quote from: G0HZU on January 06, 2014, 12:43:37 amLol same thing happened to your message that happened to mine..Yes, for some reason the wrong name was applied to the quote. Hmmm.Deleted all the subsets except yours, hopefully this one works.Sent from my iPad usingTapatalk

author: dajt
author_rank: Contributor
timestamp: June 25, 2014, 11:32:33 pm
content: Quote from: free_electron on December 15, 2013, 05:48:30 amI've been wondering about that since I started reading about electronics. My other hobby is model engineering where .0001" is always called a "thou". I had never heard them called "mils" before looking into electronics. Even US model engineers use "thou" and not "mil" in all cases I've read.I figured out what was meant simply because 100 mil pitch was 2.54mm, not 100mm. But it grates when reading it.

author: IanB
author_rank: Super Contributor
timestamp: June 26, 2014, 02:35:25 am
content: Quote from: dajt on June 25, 2014, 11:32:33 pmI think you mean 0.001 inches rather than 0.0001 inches, but that may be why the thou exists in the first place...On a related note, you may be interested to know that M is a prefix meaning thousand, not million, as in 5 Mlb/hr is 5000 lb/hr. 5,000,000 lb/hr would be 5 MMlb/hr.

author: miguelvp
author_rank: Super Contributor
timestamp: June 26, 2014, 03:14:26 am
content: Quote from: IanB on June 26, 2014, 02:35:25 amWouldn't that be "V MM lb/hr"?Edit: lb/hr as in libra/horae

author: jay
author_rank: Regular Contributor
timestamp: June 26, 2014, 04:06:01 am
content: I wonder why it's so hard for the US to give up the ancient system. Pretty much every other country in the world has switched from their traditional systems to the well specified metric system / SI units. Some countries had much more wonderful traditional units than the imperial system. The Finns measurement distance in poronkusema (reindeer leaks) that measured the distance a reindeer can walk without urinating. It's twice as hilarious for me due to a dual meaning. If they could give up such a unit why Americans have to be so stuck with measuring with their feet?Well, it seems impossible for many Americans to learn a second language. I speak quite fluently three languages. Maybe it's better that we speak English and convert to imperial units when dealing with Americansit's not too hard for us.

author: miguelvp
author_rank: Super Contributor
timestamp: June 26, 2014, 04:12:23 am
content: Let me guess, you can speak Russian, German and English. Well in here we all speak English so we don't need the rest, but I know Spanish and French I can think on all three languages, well maybe not French anymore since I haven't used it in a while but takes me a week in France to get it back.

author: Kremmen
author_rank: Super Contributor
timestamp: June 26, 2014, 04:40:01 am
content: Quote from: jay on June 26, 2014, 04:06:01 amWhat do you mean "did"? We still do. Or at least the Sámi nomads who actually own reindeer do, up North. But admittedly, they seldom fabricate electronic gizmos or do any other kind of precision measuring.More on the topic; i have lived all my life in the metric world and have yet to see a problem. You can argue for all kinds of binary divisions and gauges for this and bushels for that until the cows come home. Compared to the simple and efficient metric/SI system it is all furlongs per fortnight and belongs to the late middle age. My every contact with the "imperial" system has been an unhappy one so not for me thanks. I don't care one bit what the merkins do between themselves as long as i don't have to be a part of that. Always buying German cars i can be at least sure my toolbox stays all metric

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: June 26, 2014, 05:21:50 pm
content: What theadvantageof havingtwo different systemsin the first place?I can come up with some reasons, but none of them seem to fit or even make sense.Because now you can:- isolate yourself from the rest of the world.- complicate technical stuff on purpose.- do unneccesary math.- fabricate and sell twice as many different parts, plus all the conversion stuff.- well..... just because you can.Am I missing something?

author: Monkeh
author_rank: Super Contributor
timestamp: June 26, 2014, 06:51:29 pm
content: Quote from: sunnyhighway on June 26, 2014, 05:21:50 pm'merica.

author: miguelvp
author_rank: Super Contributor
timestamp: June 26, 2014, 07:13:19 pm
content: Quote from: Monkeh on June 26, 2014, 06:51:29 pmAnd the cost of changing everything.

author: mrflibble
author_rank: Super Contributor
timestamp: June 26, 2014, 07:26:30 pm
content: Quote from: miguelvp on June 26, 2014, 07:13:19 pmAs opposed to the cost of keeping using a somewhat outdated system while the rest of the world has moved on.

author: miguelvp
author_rank: Super Contributor
timestamp: June 26, 2014, 07:27:33 pm
content: No one forces you to use it. Demand it from your suppliers that you won't buy anything until they changeAs far as outdated, if it's still in use it's not outdated.Edit: I really don't understand the complaints, don't use thous and be done with it, you have choices of packages.What uses thous anyways, DIP, breadboards, through hole, SOICs, SOPs little else.

author: dajt
author_rank: Contributor
timestamp: June 26, 2014, 09:58:32 pm
content: Quote from: IanB on June 26, 2014, 02:35:25 amI did mean 0.001".

author: David Hess
author_rank: Super Contributor
timestamp: June 29, 2014, 05:57:43 am
content: Quote from: Lightages on December 15, 2013, 02:37:03 amI will agree once the metric system is changed to use base 12 instead of base 10 but then it would not be metric.

author: David Hess
author_rank: Super Contributor
timestamp: June 29, 2014, 06:00:19 am
content: I am in the US and used to mils meaning thousandths of an inch and millimeters meaning millimeters. I have never seen them used any other way.

author: rolycat
author_rank: Super Contributor
timestamp: June 29, 2014, 09:52:07 am
content: Quote from: David Hess on June 29, 2014, 05:57:43 amQuote from: David Hess on June 29, 2014, 06:00:19 amGiven this devotion to base 12, shouldn't a 'mil' should be 1/1728 of an inch?Or - since inches are frequently divided by binary fractions - 1/1024 of an inch?The great thing about standards in the US is that there are so many to choose from...

author: plazma
author_rank: Frequent Contributor
timestamp: June 29, 2014, 10:56:23 am
content: Quote from: rolycat on June 29, 2014, 09:52:07 amhttp://xkcd.com/927/

author: David Hess
author_rank: Super Contributor
timestamp: June 29, 2014, 02:47:09 pm
content: Quote from: rolycat on June 29, 2014, 09:52:07 amSure but as written, it would still be 1/1000 of an inch . . .QuoteOr octal making it 1/512 or 1/4096 depending on if the standard word width was 9 or 12 bits.

author: mrflibble
author_rank: Super Contributor
timestamp: June 29, 2014, 03:23:38 pm
content: Quote from: rolycat on June 29, 2014, 09:52:07 amAwww yeah! The reciprocal kibi-inch.I mean, ifcircular mil-foot(*) is a thing why stop there?(*) no, seriously.

author: David Hess
author_rank: Super Contributor
timestamp: June 29, 2014, 04:46:02 pm
content: Quote from: mrflibble on June 29, 2014, 03:23:38 pmIf only our chordate ancestor had had 4 digital structures instead of 5.

author: rolycat
author_rank: Super Contributor
timestamp: June 29, 2014, 07:29:59 pm
content: Quote from: David Hess on June 29, 2014, 04:46:02 pmAnd four arms.Then not only would base 16 be the natural choice but we'd all finally be able to wield a soldering iron properly.

author: Monkeh
author_rank: Super Contributor
timestamp: June 30, 2014, 02:31:31 pm
content: Quote from: mojo-chan on June 30, 2014, 02:30:28 pmOr millilitres.

author: David Hess
author_rank: Super Contributor
timestamp: June 30, 2014, 09:11:47 pm
content: Quote from: mojo-chan on June 30, 2014, 02:30:28 pmI have always seen it written as "mils" though instead of "mills" and I always use "mm" or "millimeters" to distinguish them.

author: Kremmen
author_rank: Super Contributor
timestamp: July 01, 2014, 05:30:18 am
content: If one utters anything sounding like "millis", it automatically means "millimeters". In the US of A it might mean thousandths of an inch but not for the rest of us. OTOH, nobody i know would _write_ "millis", it is always "mm" which is also the official abbreviation.Another pet peeve of mine is the cavalier attitude so many take towards correctly abbreviating units and prefixes. How many times you see mHz when the writer obviously means megahertz, not millihertz. Over time you see all possible incorrect combinations of practically any units you care to name. General ignorance? Sure, but also i think, the confusion bred by the cacophony of units in the imperial "system". When you have dozens of industry and topic specific units for the same dimension, with arbitrary conversion factors between, how can you not get confused. Why can't say volume just be volume? Why do you need bushels, barrels, gallons, pints, drams, liquid ounces, hogsheads, flagons and whatnot? I and most of the world did and do perfectly fine with liters. How easy life is when you don't need a single conversion constant between units, let alone between units of the _same_ dimension. /Sorry, feel better already.

author: IanB
author_rank: Super Contributor
timestamp: July 01, 2014, 01:16:41 pm
content: Quote from: Kremmen on July 01, 2014, 05:30:18 amSee, that's why volume can't just be volume. If you write down a number, you must always write down the unit of measure. The SI unit of volume is m3and that's what appears in my calculations and specifications. I can't remember the last time I used or encountered liters in an engineering context.

author: Kremmen
author_rank: Super Contributor
timestamp: July 01, 2014, 07:10:20 pm
content: While true in the strict sense, that is a slightly contrived argument. For internal consistency the _SI_ system has to use volume derived from basic unprefixed units and those are consistently used in scientific and technical calculations. But the _metric_ system recognizes litre (or liter) as a valid unit of volume. One is still allowed to be practical and we don't have to sell drinks by the cubic meter when the centiliter is much more understandable, while still playing inside the same system. If you need to know how many centiliters there are in a cubic meter, it is just a question of adding the required number of zeros - 5 in this case. No magic multipliers needed. So whether basic SI or derived units, they are just multiples of each other in the same decimal progression as all metric units and prefixes (now quickly: how many drams in a hogshead?).As to writing down the unit of measure, i don't really follow the point you are making. In practical life you end up always specifying the unit whether it is strictly needed or not. I mean i can make a shopping list including say milk. I could write "buy 2 milk" and a valid assumption would be "2 liters", but it _could_ mean many other things as well. Such as "buy 2 of the usual containers" and those could be say .5 liter or 1.5 liters each, both commonly available around here. Or you could say the distance between these 2 points is 100. 100 what? meters, kilometers, megameters? No, in practice you always include the unit of measure whther it is the basic unit or a prefixed one - and especially because it might be.So i see these 2 issues as totally separate ones.

author: IanB
author_rank: Super Contributor
timestamp: July 02, 2014, 01:59:46 am
content: Quote from: Kremmen on July 01, 2014, 07:10:20 pmWhen you said,QuoteI interpreted that to mean "Why can't volume always use the same units of measure (liters)?" You seemed to be saying that if volume is "just" volume, and is always liters, then we don't need to specify what units of measure we are using as liters will be assumed.Evidently you had another meaning in mind, but then I'm not sure what you are saying. Perhaps you just meant that the powers of 10 conversion between ml, cl, L, or m3were convenient?While that is true, you still need a calculator for any non-trivial calculation such as determining the volume from the equation,PV=nZRTfor instance. Powers of ten only help you out in the simplest of cases.

author: VK5RC
author_rank: Unknown
timestamp: July 02, 2014, 03:27:17 am
content: Whilst I find the metric system so much easier than imperial systems, the metric system is not universal, aircraft height is in feet and distance/speed is nautical miles /knots. I think we should accept the differences, good documentation of measurements including the units is vital in important documents. :-)

author: Unknown
author_rank: Unknown
timestamp: July 02, 2014, 05:03:47 am
content: Quote from: VK5RC on July 02, 2014, 03:27:17 amAnd just to confuse things: knots and nautical miles per hour have not always meant the same thingas they do now, andnautical miles, knots, and nautical miles per hourhave varied in different parts of the world and in different domains (marine vs aviation) at the same time within living memory.Something to remember if you find yourself having to navigate by dead-reckoning using maps created prior to about 1970...(editedas shown)

author: Kremmen
author_rank: Super Contributor
timestamp: July 02, 2014, 06:05:00 am
content: Quote from: IanB on July 02, 2014, 01:59:46 amWell, thinking more carefully about what i wrote earlier, i guess i meant to ask, why can't we use one internally consistent system of units for a given dimension, and by extension a set of consistent units across the board. Especially since those have been around for a long time and almost everyone uses them already.Whatever the unit, it would be silly or at least very non-intuitive to use the basic unit only for every case. The scale of the world we live in today extends from the far sub-microscopic to the ends of the universe so there could hardly be one convenient unit to measure the full scale of anything from end to end.The medieval people lived in a world where man was the measure of all things and scales extended from yout thumb to the tips of your extended arms or - at most how far your horse could run in a few days. Combine that with the lack of scientific thinking and you are bound to end up with a different name for each different unit or scale of measurement. And it is only natural that these units are not related to each other in any meaningful way, nor do the magnitudes of the units agree from region to region. Why some think this is a good idea is beyond me.Even modern science uses units that the SI system does not recognize. Examples such as the electron-volt (energy), parsec i.e. parallax-second; light-year (distance), barn (scattering cross section), jansky (flux density). I am not entirely happy with the thinking behind this because it re-introduces the magic multipliers but then nobody asks me about it.QuoteYes i guess that is more or less what i am saying. The magnitude of metric dimensions is of course not the point, any reasonably sensible absoute values would serve as well..You are right of course that powers of ten don't make the physics (or whatever the topic is) simpler; there is no way around that. But what they do is remove all of the spurious conversion factors between units. Those do not add anything to the substance of the matter, only needless complexity and a source of potential errors. We all know what can happen when you build space probes with 2 sets of dimensions. Granted the blame there is not directly on imperial or metric system, but in my mind it is an example of the confusion that can follow when you have lots of unnecessary fudge numbers sprinkled around the formulas.In the end i guess the whole question is only really relevant for international contexts and technical and scientific calculation. If the average hausfrau wants to buy her milk in bottles of 1/64 flagon then nobody is the worse off even though the neighboring county has a different volume for their version of flagon. Also the brits can have their sacred pint which is of course different from everyone else's pint but if that is the only thing between their pubs and total annihilation then so be it. Just on general principles i myself refuse to buy the pint-sized cans of beer now in fashion and grab the regular half-liter ones instead.