There are three issues that I would guess would cause problems -- and this is only guessing, so take this for what it is worth:
1) Regulating the pressure and speed so that you erode paint/dye but not copper/board. Particularly on areas where you are eroding a block of paint/dye, I would wonder if the speed of erosion is different when there is paint/dye on each side, vs. only on one side of the line. Further, I would expect that it would require a different pressure or timing to start or stop a feature than to continue a line. How easy is it to control the pressure with some level of exactness?
2) Overspray/interference -- since you would not be cutting through the board, the water will be bouncing up off the board, right into the path of the water jet. My guess is that this "overspray" will degrade the resolution of the waterjet, making #1 even more difficult.
3) Electronics and mechanical systems in a wet environment would likely increase the difficulties of the design by an order of magnitude.
No doubt, with sufficient effort and expense, all of these problems could be overcome ... at which point you will have to "paint" the board and wait for it to dry. Then you will have wait a good bit of time for the waterjet process to actually produce the design on the board -- this is not going to be a fast process, and the time required will increase as the complexity of the board increases. And after all of that, you still have to etch the board.
Meanwhile, I can produce boards ready to etch in about 5 minutes using toner transfer, with 8/8 dimensions. If I needed finer dimensions, I would make the very small investment required to go with a UV-exposure process.
--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:
>
> Andrew, indeed it might be something I might like to try. Just curious why
> do you think it would not give suitable results?
>
>
>
> _____
>
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Andrew
> Sent: Wednesday, January 12, 2011 6:56 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: water jet and spray painted board
>
>
>
>
>
> Given that waterjets are used to cut steel, I expect something like this is
> feasible ... but I have doubts that it is going to give very good results.
> Of course, you may prove me wrong!
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com> , "Jeff" <jeff.heiss@> wrote:
> >
> > To follow up on the "Electrical Discharge Machining plus painted board
> plus CNC x-y table" discussion, I would like to suggest a similar idea. What
> do you think of spraying a PCB with automotive spray paint and using a water
> jet to remove the paint. After removing the paint, the board is etched.
> Electric pressure washers produce 1800 psi. Hypodermic needles are available
> in .004". Do you think there would be enough pressure out of a .004" opening
> to remove the coating on the board?
> >
> > Jeff
> >
>
>
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>
> [Non-text portions of this message have been removed]
>