Homebrew PCBs

Hi, a lot of laser printers do this,and it can usually be fixed by a 
professional service and laser alignment......mostly service software is needed 
as well as alignment targets.I have yet to find a source of these :), and if 
they were available,i expect the cost will be unreasonable.





________________________________
From: Andrew <a_wake@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Wed, April 6, 2011 3:55:52 PM
Subject: [Homebrew_PCBs] Re: HP Laserjet 4050 prints over-size

  
Sounds like it's time for a conversion to Kicad! :)

Yes, I know -- that doesn't help a bit with the current project ...

--- In Homebrew_PCBs@yahoogroups.com, "David C. Partridge" <david.partridge@...> 
wrote:
>
> I've printed directly from the PCB software, and also from GC-Prevue using the 
>Gerber files from the PCB software.  The output is identical in either case.  I 
>don't believe Ultiboard has any ability to scale the output Gerber files.
> 
> Now if I had the GC_Prevue Plus ($495) then I believe that would allow me to 
>scale everything in only one direction (though whether it would allow fractional 
>percentages I don't know).
> 
> 
> Regards,
> David Partridge
> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On 
>Behalf Of Andrew
> Sent: 06 April 2011 15:42
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] Re: HP Laserjet 4050 prints over-size
> 
> David,
> 
> What software are you using to generate the image? Many have the ability to 
>scale the output in very fine amounts. E.g., Kicad gives the option to adjust 
>the X and Y scales independently down to 6 decimal places. (I have trouble 
>believing that one can actually obtain or use that level of precision, 
>especially with toner transfer, but ...)
> 
> This may be what you are referring to when you talk about the printer driver 
>only allowing whole percentages, but I wonder if perhaps you are generating the 
>image from the PCB software, and then trying to scale it when you print -- as 
>opposed to having the PCB software do the scaling.
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com, "David C. Partridge" <david.partridge@> 
>wrote:
> >
> > I just got a 36x2 way card extender type edge connector, 0.156 pitch to fit 
>the card extender PCB I made with toner transfer printed with my HP Laserjet 
>4050.
> > 
> > I found that the PCB I so carefully created in my PCB design package has 
>ended up slightly oversized - over the 36 ways the distance from first to last 
>should be 5460 mils and is shown as such in the PCB design software.  The 
>finished PCB is larger at 5490 mils over this distance, which doesn't sound a 
>lot, but that's about 0.76mm which isn't a trivial error.
> > 
> > The whole board should be 8.1875" (207.9625mm) but the printed outline is 
>actually 209mm.  So call that a 1mm error which is HUGE.
> > 
> > This works out to be about 1.005 times the size it should be.
> > 
> > In this case, there's (just) enough leeway for the board to still work as a 
>card extender without things shorting or failing to connect, but in general this 
>level of error is a disaster.
> > 
> > The printer driver won't scale except in full percentage points, and while 99 
>percent is closer to 99.45% than 100%, it isn't right.
> > 
> > Has anyone worked out a good solution to this problem.
> > 
> > HELP!
> > Dave
> >
> 
> 
> 
> 
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> 
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