At 10:20 AM 2/3/99 -0500, [log in to unmask] wrote:
>        Quiz:
>        Name three PCB Tape suppliers..
>        OK.. Ones Bishop Graphics.
>        Get all thre answers correct and become a Certified Hand Taper.

Gad, I bought mylar from all kinds of places, and I remember some other
company, in fact, two, but the Bishop stuff was quite good and I never
bought any of the other stuff. I've forgotten their names.
>
>        Bonus points for answering this question.
>        Why does the blue grid not show up on the artwork films??

Any printer or graphic artist would *still* know the answer to this. The
reason is the same as why graphic artists use blue pencil to mark up films.

But my designs didn't have blue grids on them. I never bought that stuff;
it was inordinately expensive; instead I used regular mylar I could get at
the local art store -- but I ended up buying it in bulk from Echo, I think.
Still have some. Nice stuff, for lots of uses. I had several precision
grids which I used *under* my tape-ups. The pencil sketch was put *behind*
the precision grid so as not to obscure it. The grid was a 50 mil grid (the
blue stuff only came in 100 mil grid, as I recall), and I would run the
0.025 tape in the middle of the grid lines, which was much more accurate
than trying to put it *on* the lines. This was all at 2:1 scale, so I was
getting 12.5 mil traces on 25 mil grid. But I was effectively using a 12.5
mil grid by using the half-grid. My accuracy was consistently better than 5
mils at 2:1, that is 2.5 mils at 1:1.

Of course, one of the really cool things about CAD was perfection in the
artwork. I pretty much ruined my eyes doing tapeups, or at least fixed
their focus at about six inches....

[log in to unmask]
Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433

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