rE:Re:RE: programming by hand

Bill,

Good points! Particularily about the tolerancing, that's a big, big
problem with Cad files.

Thanks for reminding us of that.

Doug

--- In CAD_CAM_EDM_DRO@egroups.com, "Bill Griffin" <bill@g...> wrote:
>
> I work almost exclusively with ProE files and ProE generated
> iges files for machining mostly 2.5 D parts. I machine parts
> directly from the geometry files provided, usually before
> prints are even generated.The biggest problem I had in the
> beginning was convincing the 10 or so mechanical engineers
> that the geometry they were creating needed to represent the
> actual part they wanted me to machine. this meant that the
> model file needed to have all the geometry set to the
> nominal of whatever tolerance they wanted. Typically, they
> would draw something at 3 inches and then they would
> manually dimension the print with a 3 inch plus 0 minus .010
> tolerance While some will say that this is not a problem, it
> is when you are machining the parts from the model files
> sometimes weeks before drawing files are actually created.
>
> I have been able to convince them to provide proper files
> for parts machined in house but unfortunately I still see
> some parts being sent to outside shops where the electronic
> files we provide are not representative of what we want
> according to the print. I see the purchasing guys arguing
> with the shops over NRE (Non Recurring Engineering) costs
> because "well we sent you the IGES files, why should we have
> to pay you to redraw the part."And in case where the vendor
> simply uses the geometry files we sent to machine the parts
> in the same manner I do in house, our inspection department
> rejects the parts because they do not match the paper
> drawing. In these cases, its up to the vendor to either fix
> the parts or he doesn't get paid.
>
> Bill Griffin
> www.grifftek.com/links.htm