The bit of the chemicals in the kitchen is valid. Most give off chlorine =

gas during the process, and I have had that rust all kinds of nice tools =

including wood chisels in my basement with an exhaust fan. Could you do =

the etching outside, maybe a small heated cheap enclosure out of plywood =

and one of those under desk heaters, or even a propane torch blasting on =

a radiator thing. Does the building have an exterior electrical outlet =

to plug into?, or could you run an extension cord out the window. Heat =

and ventilation could be 12 volt, run off car battery, don't think =

were're  thinking much amperage. How about a small chemical exhaust hood =

sort of thing, say a 1 foot cube, a muffin fan, and exhaust out the =

window. Shouldn't take much fan to just create enough air movement to =

keep the fumes going in the outside direction. Just brainstorming a bit.:)

Rikard Bosnjakovic wrote:
> The story is this: I live in a small apartment with my fianc=E9e, who is
> anything but a computer/electronics nerd. Also, she has strong
> opinions about me etching PCB's in the kitchen (due to the lack of
> space for a proper "chemistry room" with a place to heat etchant),
> because of using acids. Myself I do not mind, but I have to respect my
> fianc=E9e.
> =

> So I got this brilliant idea of mine some days ago. I will construct
> some device that drills/mills the PCB's for me. I have seen a lot of
> people building their own CNC-devices, so I thought this might be a
> nice idea. Not only because I will have a project active (I tend to
> get a lot of frustration when I'm out of ideas), it will also let me
> apply theory from my mechatronic engineering-studies. I'm still on the
> first year (of three), so even if I don't have a lot of theory in the
> luggage, it will atleast help me apply some practical work for the
> mechanics course (which I find do a lot of brain damage to me, tough
> course that one).
> =

> That said, what I'm thinking of is something like this; a metal
> construction (looking like a cage), with an X/Y-plane (to put the
> PCB's on) and a dremel-tool, or similiar, sitting on the Z-shaft. The
> construction will have three stepper motors (one for each axis; two
> for moving the plane and one for the dremel/whatever up and down) and
> a PIC-based controller. The controller gets its instructions from a
> computer using serial link (I'm having MAX232 in mind, but perhaps
> parallell transfer is better), like receiving all X/Y-coordinates for
> copper tracks, drill holes etc.
> =

> Instead of milling a whole board, I was thinking that when the board
> is ready, it will - in my CAD-program - be saved in image-format (png
> or whatever). I will then write an application that scans the image
> and finds all the traces / holes. When a trace is found, it will apply
> a graphical outline to it. The outlines will be where the mill will
> hit and run on, and something similiar will go for the holes. When the
> image is done processing in my program, it will in a way or another
> convert all the outlines to coordinates - or similar - and transfer to
> the controller, which will then move all the steppers to the correct
> position and start the milling (or whatever the correct term is).
> =

> What I've written above is probably super basic for any
> CNC-experienced person, but since I have zero knowledge about
> mills/CNC/drilling/etc I feel the need to describe the project deeply
> down to the gory details (since I will, at the same time, describe it
> to myself). When (if) finished - it will help me a lot, in a lot of
> ways. It will make my PCB's and my fianc=E9e will be more than grateful
> when I return all acids and dangerous stuff to the recycling center.
> =

> I have seen a few constructions like this, but for this one I don't
> want any ready-built schematics or anything like that, I want to go
> from square one and reinvent the wheel. Besides getting a good tool, I
> enjoy the taste of learning new things and constructing stuff
> completely on my own (with other peoples' guidelines, ofcourse). Now,
> the only knowledge I have about anything of the above is programming
> the PIC. Thus I will have to learn more about stepper motors, about
> serial communication (RS-232), reread a few chapters in my mechanics
> book about momentum and forces, and a few other things.
> =

> So, this is where the experienced PIClist comes in.
> =

> * Is my idea feasible?
> * What do I want to learn about stepper motors, except how to make them r=
otate?
> * Is RS-232 the way to go, or should I aim at parallell ports?
> * Is the idea of making an application that "outlines" PCB-traces a
> good idea or waste of time?
> * What do I need to learn more about how to pick a "good enough"
> stepper motor that can handle the required force in milling a single
> sided copper clad?
> * What other questions should I ask myself about this project?
> =

> I'm looking forward in hearing your comments.
> =

> =

-- =

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