Rainer Schmidt wrote: > On Fri, Jun 12, 2009 at 5:26 PM, Andy Pugh<a...@andypugh.fsnet.co.uk> wrote: > >> 2009/6/12 <cmg...@sover.net>: >> >> >>> My Favorite unit >>> > > In Germany we also use Angstrom per Millennium as Bureaucratic Unit. I > observe similar speeds in the US. There seems to be some cross > contamination in between processes. > > ------------------------------------------------------------------------------ > 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 > > My favorite unit is not a unit at all. It's instructions on a drawing that used to mean something to machinist. Such as: "Machine In a workman like manner" which I think meant to make it like a machinist and not like a jack legged mechanic. Another was written on a drawing with dimensions and no tolerance but said, "Make to fit and function". God help the guy that tried to make a spare part to the drawing. Another thing often on a drawing was the bolt size length thread pitch and so on. The position of the holes to be tapped was given but know depths. The machinist was expected to now how deep they should be. A steel bolt that was to go into as steel housing was to be tapped to the diameter of the bolt. That was the correct thread length plus a little :-) This to allow the bolt to break before stripping the thread. If the housing was aluminum the machinist new the course thread was to be two times the bolt diameter. This again to allow the bolt to break. No depth dimension was ever put on a tap drilled hole because you had likely ground a new lead on your tap when it was needed. The engineer didn't know how long the lead was so it was up to the machinist. The only notation on the tap drilled hole other than location might be "drill through or through drill". A tolerance was given on bolt hole location but no hole size, the machinist knew what size hole and counter bore based on location tolerance. In my opinion this was a huge complement and show of respect for the ability and knowledge of journeyman machinists. Often you were given a shaft size and told what class fit the bore was to be without a dimension. I ran a shop with 30 machinists in it. The only time I ever told a machinist how to do a job was if someone else was to do some other operations on it and most of my guys didn't even need that help. I darn sure didn't hold back though if I didn't like the job he did or how long it took. Each of them had a couple of apprentices. When I hired a kid in the shop he served a four year apprentice ship when he finished he was a second class machinist. After six years five or six years he was first class and was expected to take on an apprentice that he hired. In nine or ten years he was a master machinist had a two machinists working for him and each of the machinists had a second class machinist and several apprentice boys. All these guys had a small gerstner toolbox which I gave them when the finished their appenticeship. the older guys almost never quite though some of the youg ones did when their apprenticeship was over.. I lot of the boys quit the first and second year. Most of these master machinist worked directly with Nassa engineers and were very respected by them. They made wind tunnel models, stings and space mock ups and some things that went into space. The made steam turbine rotors for Battleships, spare blades, babbitt bearings and some bearings for propeller shafts 26 inch bores, babbitt lined. These guys now own and run the shop. It is smaller in size but still makes them a good living. I am retired. The story about Nassa making one part metric an the other imperial was tongue in cheek. The imperial dimensioned on the part had metric bearings in it. We worked on that part and we made the arm on the first Mars Lander :-[ The one that didn't work. What they did do for a short time was to dimension in inches but they represented metric dimensions. They only did that for a short time as they slowly converted and the builders ,mechanics and machinists got used to working in metrics. Mistakes ran rampant during that period. Doug
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