Homebrew PCBs

*I didn't ever know the speed of what I used to use, but in comparing it in
my memory with a 45 rpm record (also from memory), I'd guess it was about
twice that fast. One certainly kept one's fingers away. While it's true the
perimeter would be moving much faster than the center as measured in
inches/second (or some other linear unit), I think in this application it's
angular velocity that matters and that's the same at all points. At 90 rpm
that would be 32,400�/minute. *
*
*
*We used to mount the pcb material, start it spinning, and then carefully
pour a small amount of emulsion at the center. Since "center" is really
only a theoretical concept, it was always off center enough that the
emulsion was flung across the board, hitting the sides of the open
enclosure the thing was mounted it. It don't think we ever cleaned up that
mess. It got pretty thick after a while.*

73,

Todd
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K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
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QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


On Sat, Apr 6, 2013 at 9:14 PM, James <bitsyboffin@...> wrote:

> **
>
>
> On 07/04/13 15:58, Todd F. Carney / K7TFC wrote:
> > Ben,
> >
> > I think he was referring to the capacity of the spin machine he showed in
> > the photos. I used to use spin coating, and there's no reason it can't be
> > bigger.
>
> How fast does it have to spin? The velocity of the outside edge of the
> board would be getting quite high I imagine as you increased the board
> size.
>
>  
>


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