Homebrew PCBs

My company makes low cost laser engravers (
http://www.fullspectrumengineering.com/co2laserv2-40w.html) and laser
engraver electronics /software (
http://www.fullspectrumengineering.com/RetinaEngrave.html)

I have played with 2 plotters already for PCB using a sharpie: Roland DXY
880 and DXY 1120.

Both of these had WinXP drivers (no Win7).

As others have mentioned, plotters are made to go at one speed and you can't
really slow them down.  I think mounting a laser would be pretty easy to the
12v solenoid down circuit.  You can tap 12v from the head also but you would
need to overcome the speed issue somehow.

Our CO2 laser works fine for stripping off paint, etc but you still need to
etch it and the dot size isn't that small (diffraction limited to around
0.002-0.005" depending on your lens).  You also need to paint the board and
also etch it afterwards which no longer makes this process fast.

We programmed a full set of printer electronics from scratch using our
RetinaEngrave controller including high speed rastering and vector modes.
 This would be a lot easier to do than hacking the plotter but of course at
higher cost (except remember the DXY 1120 was around $5000+ when new).  Our
software is also much easier to use since we can just print from any
application and it goes to the laser.  Just print your Gerber file and
instead of ink it ends up laser workpiece.

We used to run Mach3 but then realized GCode really isn't that suitable for
a laser because of the delay between turning the laser on/off and the time
it takes to start moving.  Basically it leave pierce points everywhere.
 When we rewrote everything we knew the exact velocity and position as a
function of time and were able to modulate the laser power around corners,
etc.  Mach3 also uses a very basic acceleration algorithm which isn't nearly
as good as our own in house vector trajectory algorithms.

Raster mode is easier to implement especially when you have a solid state
laser that you can turn on / off basically instantly.  Some other group
member mounted a blu ray laser to an inkjet printer and it worked pretty
well but no one else was able to replicate it due to the complexity.

Since we designed 100% the laser electronics and software, we could help
people modify to use other laser sources if they wanted (standard 5v
high/low signal to a mosfet).

We tested with a high powered q-switched DPSS YAG and also q-switched fiber
laser and were able to directly ablate copper in these scenarios.  However,
these lasers were not cheap.

On Sun, Feb 6, 2011 at 10:10 AM, designer_craig <cs6061@...> wrote:

>
>
> I would look at hacking one of your old plotters. Remove all but the motors
> and possibly the power supply. If they used stepper motors you are in good
> shape just get a low cost two channel stepper driver bord off ebay then
> drive it Mach3 software. Now it will dance to G-Code which is very close to
> Gerber.
>
> If they were built with servos you need to find a low cost servo driver
> like the open source UHU servo board.
>
> Or even change the motor out to low cost steppers.
>
> Then mount a laser diode on the pen holder.
>
> Sounds like a fun project.
>
> Craig
>
>
> --- In Homebrew_PCBs@yahoogroups.com, "Boman33" <boman33@...> wrote:
> >
> > I currently have, and I have used several other models of HP pen
> plotters,
> > but they are old and all of them were analog and took a varying voltage
> as
> > input. In other words, not easily controlled by a computer without
> > additional digital to analog converters.
> > Bertho
> > ======================================
> > From: designer_craig Sent: Saturday, February 05, 2011 14:25
> > PC stock would not work in a larger HP plotter, you have a grit roller
> and a
> > rubber pinch roller. It depends on the grit pattern digging into the
> paper.
> > Alos the paper bed is curved. You also need a roller set at the other
> side
> > of the paper or it will not run straight.
> > Best bet is to find a smaller 11 x17 flat bed HP pen plotter. They had an
> > electrostatic system for holding the paper down and a gantry pen holder
> > system.
> > Craig
> >
> > --- In Homebrew_PCBs@yahoogroups.com, Mark Lerman <mlerman@> wrote:
> > > Yes, I had heard about the indentation. I assume the indents are on
> > > the bottom so that I could mount the pcb on paper or cardboard?? Can
> > > a pcb fit mechanically without modification?
> > > Mark
> > >
> > > At 04:19 PM 2/4/2011, you wrote:
> > > >Note:
> > > >The pen moves in the X plane and the PAPER moves in the Y plane. A PCB
> is
> > > >rigid so you would need to attached to the equivalent of a paper
> carrier.
> > > >
> > > >The plotter technology is clever with the grit wheels actually
> indenting
> > the
> > > >paper on the first pass so the paper on future passes back and forth
> > track
> > > >the previous indented markings.
> > > >
> > > >A long time ago I played around with this idea but I was using a fiber
> > optic
> > > >cable to keep the laser stationary and the weight down for the pen
> > assembly.
> > > >Today lasers are much smaller.
> > > >Bertho
> > > >==============================
> > > >
> > > >From: Mark Lerman Sent: Friday, February 04, 2011 15:38
> > > >At 03:25 PM 2/4/2011, you wrote:
> > > >
> > > > >--- On Fri, 4/2/11, Mark Lerman <mlerman@> wrote:
> > > > > > From: Mark Lerman <mlerman@>
> > > >homebrew_PCBs@yahoogroups.com
> > > > > > Date: Friday, 4 February, 2011, 18:52
> > > > >
> > > > > > work. Questions:
> > > > > >
> > > > > > 1 - How good is a plotter's resolution?
> > > > >
> > > > >Just a quick answer: the basic resolution of HPGL, the
> > > > >HP plotter language that nearly all plotters use, is
> > > > >40 steps per mm. So, if you add 40 to a co-ordinate,
> > > > >the pen moves by 1mm. Now, I don't know if this is
> > > > >the mechanical resolution of the plotter, but it sets
> > > > >an upper limit to resolution, at least.
> > > >
> > > >Thanks - that would be .001 inch (1 mil) per step, more than adequate!
> > > >Mark
> >
>
>  
>


[Non-text portions of this message have been removed]