Re: [CAD_CAM_EDM_DRO] Re: HP 7475 plotter

Hi,

Staedtler Lumocolor permanent #318 in red work best for drawing a circuit
directly onto a board. Set the drawing speed to the slow. You will need to
cut the case of the 7475 to allow for the longer pen. Mounting the new pen
is easy by using the casing from a pen meant for the machine and removing
the insides to a good fit on the Staedtler. Machining a holder from
aluminium is also easy.

Regards,

Terry

> When hand etching I just use a extra fine permanent marker. But I
> don't how well a plotter could handle it. I always had to pay
> attention to the shape of the felt tip. I've free handed a .8mm
> pitch 44 pin TQFP. That is an experience I hope never to repeat.
> For slightly larger sizes though, just replacing a pen with a
> permanent marker should work. Are the regular pens felt tip? You
> could get a photo-etch board, draw the design with any ink, expose
> the board and etch like any photoetch procedure.. (or just laser
> print it to a clear sheet and expose...)