2009/6/13 Kirk Wallace <kwall...@wallacecompany.com>: > I started out as a draftsman and my understanding is that drawings were > made for the purpose of describing the shape and material requirements > of parts and assemblies, not to tell machinists how to do their jobs,
This reminds me of a dispute I had with a supplier a few years ago. I designed a multi-functional component for a bond tester, it combined a guide bore, several brackets, the bore of a pneumatic cylinder and a flexural element to guide the piston. (It was a very small-travel rocking piston). All in a stainless tool steel similar to 440C. Most of the dimensions for the general geometry were +/- 0.2mm except for the flexural element, which was 0.2mm +/- 0.05mm dimensioned from a face with a stacked-up positional tolerance of about 0.4mm. The machinist set up his CNC mill to the centre value of each tolerance starting from a part edge and pressed "go". When the program finished the flexural element was not even there. Who was at fault? I argued that the wider tolerances elsewhere in the geometry were specifically so that they could get the flexure right, they said "You always work to mid-tolerance, and the drawing should assume that" -- atp ------------------------------------------------------------------------------ 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
