Homebrew PCBs

I think it'd be way less work to just export gerber as BMP and raster scan.

Mach3 has raster scan capability from a bmp.

Easy solution.
On Fri, Nov 13, 2009 at 12:21 PM, designer_craig <cs6061@...> wrote:

>
>
> I looked into a couple of these but I believe they are for island milling.
> Converting the xy moves from the gerber to the G-code is the easy part the
> files are almost exactly the same syntax.
>
> Its the aperture definitions that cause the problem. The origional photo
> plotters used an aperture wheel to project the correct spot size for the
> trace width and donut pads. But with the laser I will need to write macros
> to draw these from a single .001" dia spot. I took a look at Diptrace's
> Gerber output and currently they don't do anything exotic just x-y moves and
> apeture settings. For me to write and 8mill wide trace I will have to do the
> xy move 8 times with .001 offsets between writes. If this works out to be
> too slow I may have to increase the spot size somewhat. Would be nice to
> figure out how to have several different spot sizes. I guess one could use
> multiple laser diodes and just select the best one for the task at hand. It
> would be no problem selecting the correct diode in the G-code.
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com <Homebrew_PCBs%40yahoogroups.com>,
> Henry Liu <henryjliu@...> wrote:
> >
> > For your problem to convert to Gcode from gerber, there are three ways:
> > -pcb-gcode (works ok but in Eagle)
> > -export to DXF then into Cam package like LazyCAM with Mach3
> > -some commerical package made to CNC mill out pcbs from gerbers (forget
> the
> > name, was on pcb-gcode group)
> >
>  > On Fri, Nov 13, 2009 at 11:21 AM, designer_craig <cs6061@...> wrote:
> >
> > >
> > >
> > > I had the same idea last spring and purchased a 405nm laser diode with
> > > holder/lense and some Riston film off ebay. I added a heat sink to the
> > > holder and have driven it up to 110ma. At that power level it will burn
> > > through paper, so I have no doubts that it should harden the photo
> resist. I
> > > did some initial crude calculations based on the Riston data and
> estimated
> > > diode power that led me to believe it would be possible to write a
> .001" dia
> > > spot at 80"/sec.
> > >
> > > My initial plan is not to raster scan the board but to vector draw the
> > > pattern using my Bridgeport mill that is currently being converted to
> CNC. I
> > > will need to write some code to convert the Gerber photo plot file to a
> > > G-Code file to drive the mill. These files are very similar, the Gerber
> > > format being an offshoot of the G-code format. Since I plann on using a
> > > fixed spot size, wide traces will need multiple passes as will donuts
> etc.
> > > This all has to be coded in the conversion program.
> > >
> > > Currently I am working on the mill's CNC conversion and have not done
> any
> > > testing on the direct exposure part of the project. It will be a couple
> of
> > > months before the mill is ready for PCB testing.
> > >
> > > Issues to be resolved:
> > > 1.Is the exposure of photo resist linear ie. is high power UV for a
> short
> > > time the same as low power UV for a longer time.
> > >
> > > 2.Code to make multiple passes for trace and shape widths from the
> point
> > > gerber data.
> > >
> > > 3.How to get a .001" dia round spot. The laser diode output is not
> round.
> > > How to measure the spot dia.
> > >
> > > 4.How long will it take to expose a 3'x5" board?
> > >
> > > Craig
> > >
> > >
> > >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>  
>


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