Re: gEDA-user: Help ordering pcb

[Dave N6NZ <n6nz@xxxxxxxx>]

Robert Butts wrote:
> One of the pcb websites claims one common gerber mistake is a missing
> aperture list.  What is this and does PCB create it?
Short answer: Don't worry, you are good to go.

History lesson:

In the old days of RS-274D the gerber files contained X,Y, Lamp 
on/off/flash, and select aperture commands.  "Aperture" being the shape 
exposed onto the film.  This is a hold-over from RS-274D's heritage as a 
CNC tool control file -- select "aperture" being the equivalent of 
"select tool" in a CNC mill, for instance.  The first photo plotters 
were simply converted X/Y machine tool mechanisms, as I understand it. 
The apertures were sent in a separate file -- in the very old days a 
person physically loaded the aperture wheel in the photo plotter, a 
common source of errors.

These days, photo plotters work like laser printers, there is 
essentially no limit to the size of the "aperture wheel", and the 
aperture definitions themselves are contained in RS-274X formatted 
files.  PCB writes RS-274X.  Almost nobody uses RS-274D for photo 
plotters any more, although RS-274D is very much alive and well in the 
CNC machining world.

-dave

> 
> On Fri, Aug 1, 2008 at 10:36 AM, Robert Butts <r.butts2@xxxxxxxxx> wrote:
> 
>> Do I need the unplated-drill.cnc file?
>>
>>
>> On Fri, Aug 1, 2008 at 9:49 AM, DJ Delorie <dj@xxxxxxxxxxx> wrote:
>>
>>>> What is the stencil layer?  A pcb fab company wants me to identify the
>>> top
>>>> stencil, bottom stencil and outline layer.  Which gerber files are
>>> these?
>>>
>>> Stencil is probably the silkscreen layer, assuming you can figure out
>>> the other ones are copper and solder mask.  For outline, if you don't
>>> have an explicit outline layer, use the fabrication drawing.
>>>
>>> board.front.gbr
>>>        front side copper
>>>
>>> board.frontmask.gbr
>>>        front side solder (stop) mask
>>>
>>> board.frontpaste.gbr
>>>        front side paste mask
>>>
>>> board.frontsilk.gbr
>>>        front side silk (stencil or ink)
>>>
>>> board.back.gbr
>>>        solder side copper
>>>
>>> board.backmask.gbr
>>>        solder side solder (stop) mask
>>>
>>> board.backpaste.gbr
>>>        solder side paste mask
>>>
>>> board.backsilk.gbr
>>>        solder side silk (stencil or ink)
>>>
>>> board.fab.gbr
>>>        fabrication drawing (human readable, includes outline and drill
>>> makers)
>>>
>>> board.plated-drill.cnc
>>>        drills for plated-through holes
>>>
>>>
>>> _______________________________________________
>>> geda-user mailing list
>>> geda-user@xxxxxxxxxxxxxx
>>> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
>>>
>>
> 
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