Douglas Pollard wrote: > I can look at a cutter and tell you pretty close how many surface > ft per minute it is running. How many mm is that a minute and if I > knew , would I really know what that is? Thank God we don't have metric > time I guess it would have to be based on how many kilometers it is > around the world and so on and on. Just kidding about the time! > Since about 1970 in the machine shops here in the states there have > been almost no fractions used in dimensioning. Drill sizes and taps are > the exceptions. The tolerance have been such that a three placed > decimal denotes +or-- .005 A two place decimal denotes plus or minus > .20 a one place decimal equals plus or minus .100. Then comes the > unless otherwise specified note. The scales I use don't have fractions > on them at all. > Now days everybody says the can hold .0001 on a hole diameter or > location and that doesn't mean anything where the assembly of a machine > is concerned. To work, the hole has to be round to way less than .0001 > it has to be perpendicular with in some very very small dimension and > that depends on how deep the hole is. Since cad, very few fractions are > used except by those who ignore the standards or in the building trades > where almost no decimals are used. Fractions are a relic of the past. > Metrics are no easier to work with in my opinion than decimals of an > inch. They are both very simple! The only people I know that make the > claim that metrics are easier are people that use them. If you use > anything long enough it becomes your standard. > I have argued this with many German machinists and they always come > back that metric is scientific measurement because it is a part of the > circumference of the world. That may matter to a map maker but I don't
That's very unscientific definition of metric system and makes no sense in reality. > see how it matters to and engineer or a machinist. I bet nobody on this > list uses any fractions when using EMC. The truth is, at this time we > are using both and any one who can't use both only knows half his job. > Doug It's time that US adopts metric system. The law was passed on the 70's to adopt it. About the same time British switched to metric (for the most part I bet). It's only US and one other most backward country in Africa that keep dragging it's feet. US debated to adopt metric system in early 1800's but decided to keep old system as it would be too expensive. The most visible silliness in using two systems was NASA crashing Mars probe few years ago. That was due to one department using metric system, another "standard." How much easier it would be if the whole world used the same system as most companies have to do business internationally. With so many machines and gadgets with electronics around us it should be very easy to convert to metric. All illegals in the US know metric system, it's only the "natives" that are stubbornly using gauges, and other most silly ways of measuring world around them. wire gauges: the bigger the number smaller the size; sheet metal: different metal, different gauges for the same thickness! pipes: schedules (what the hell that's based on I don't know), tubing: in inches, screws: some are in inches some are numbered (?) with no relation to inches; You have to have all kinds of gauges to find out the dimensions to order raw material or replacements. And if you order in metric they look at you as you just dropped from Mars. This has a lot to do with "unions or certified professionals." Another words, in order to get contracts anywhere, you have to have a license which can only be obtained through school which hasn't changed with times. http://lamar.colostate.edu/~hillger/ Check history and see how little, almost no progress has been made since Metric Program (MP) Office was established under the Department of Commerce in 80's. -- Rafael Use metric or die. ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
