photographing vellums

On a sunny day (Tue, 02 Jul 2019 08:12:12 -0700) it happened John Larkin wrote in :

Yes cameras are good for that. Does it also work when you hang it in front of a monitor that displays white? I have no 'vellum' here to try, a white rxvt in Linux makes a nice white screen. Adjustable brightness at that.

I use 'xv' in Linux to modify pictures.

What, is that a drafting table? I moved mine out of my lab over 25 years ago. Hmm, I didn't see a drafting machine.

Yes, that's in fact a custom-built drafting table. I like to sit or stand there, look at the birds and plants [1], and draw. I find drawing with a good pencil a lot faster and more creative than working on a screen.

I do use some design automation, an electric pencil sharpener and an electric eraser.

I use blue-grid paper and follow the lines, so I don't need a drafting machine. Looks fine.

Maybe an alternative idea: 30 years ago I used to draw on A3 sized sheets of paper, printed for us with very thin blue lines, 5x5mm grid. They had a black title block and edge with 1-2-3 and A-B-C markings. When photocopying the blue lines disappeared. Pencil lines became black, good enough for first discussions with clients. Also did the 3-D drawings on those, looked fine. Of course later they were inked, on real drawing paper laid over the paper drawing.

Arie

I give my hand-drawn schematics to my PCB layout guy, who enters them into PADS and then does the board layout. He often has to create new library parts, which I don't have to do while I'm designing. I leave a lot of design notes on my vellums, that would clutter up a CAD schematic.

That's odd. Computer aided design usually lets you hide design notes so the y only clutter up the schematic when you turn them on. The philosophy is th at the schematic just presents the information that the viewer needs - it r eflects the net-list and displays it in a way that's more or less human-com prehensible - but there can be a whole data-base behind it (including all t he printed circuit layout information) which really would clutter up the sc hematic if your tried to display it all.

It's because pencil produces a lot of top-surface reflection.

I'm always dissatisfied with photos or scans of pencil drawings for that reason. Even after you apply a radical brightness/contrast adjustment they're just no-where as good as if done in ink.

Maybe if could be better if you use radical side-lighting, like below 30 degrees of incidence.

Clifford Heath.

I use a Brother MFC6490CW all-in-one, and it produces good scans of B-size vellum drawings. $300, no chips in the ink cartridges, no worries.

Cheers

Phil Hobbs