"Jim Wilkins" on Sat, 21 Dec 2019 14:29:59
-0500 typed in rec.crafts.metalworking the following:
"pyotr filipivich" wrote in message
.. .
"Jim Wilkins" on Sat, 21 Dec 2019 07:45:20
-0500 typed in rec.crafts.metalworking the following:


I retrained as a CAD guy. I remember a two part assignment:
design the casting, then design resulting part. I thought "If I
make
the casting suchly, then holding it for the machining will be
easier."
And transferring "the sketch" to the drawing I said "I can make
that" meaning all the info I need is there. Except for the note
about
the material, forgot that. Oops.


Yes, let them choose the alloy that gives them the best results and
then send a revised print.

It was on the sketch. My mistake.

OTOH, one assignment did have very specific call outs for two
holes and their relationship to each other. Nothing very specific
about where exactly on the plate they were to go. As in no dimentions
at all. ... As the Proff had said "If the engineer doesn't specify,
you can put it anywhere."
I also pointed out to the head cheese that the drawing I had, did
not specify where the line of holes was to go on the board. The other
boards had it at 1" from the top, and the program drilled them at one
inch from the top, but hey, anywhere on the board was "in spec".
That place had some "interesting" drawings.

When I talked to circuit board makers before sending out a quote
package they often would tell me they'd make the board differently
depending on their equipment and supplies on hand, so I had to adjust
the quote to fit all of them by removing some specs and relying on
past experience with their quality. For these RF circuits the signal
trace impedances were determined by my line widths and their inner
plane spacings and insulation dielectric constants.

Throughout the 70's and 80's I watched them improve from loose
commercial to demanding mil-spec standards and process control for all
their products. Everything else benefited from their ability to make
circuit boards for defense contractors whose tech was 20 years ahead
of civilian applications.

Cool.

The funny thing is that my wife teaches Montessori pre-school.
Which is everything in its place, and "control of error through the
materials". Just like assembly stations. All the parts are on this
board here, and the assembly is put together over here. If you have
any extra parts, you left something off. If it doesn't match the
outline on the assembly;board, you did something wrong. Just like in
pre-school. Bewahahahahahahaha!


--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."