Dirk wrote: > I am 100% metric and I hate it when I have to work with imperial > parts. If I have a choice I will never take the imperial parts. > Especially if it is not only about dimensions but also some heat, > power or whatever awkward unit they come up with. It is asking for > trouble with all these conversion factors. I really don't see why > anyone would prefer to work with Btu/hour, or horsepower, you name it. > In SI you can just calculate without any conversion numbers. But this > was about dimensions. > Dimensioning with it is not really hard, you only need to remember to > multiply or divide by 25.4 every now and then. But, the only advantage > I can think of was the british system, it probably has an official > name. It works with fractions and this makes threading, gears and > divisions a lot easier to calculate. Why is this something that is/was > used in the UK but not in the states? Or are there really big > disadvantages? To me, it seemed really handy when you are behind a > machine. I haven't done a lot of work with it so I can't really judge > how it is for real work. > > Dirk > > ------------------------------------------------------------------------------ > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > 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 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
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