Newbie: Converting HPGL or Gerber files

D

Douglas Simmonds

Guest
Hi folks,

I am building a CNC type PCB milling machine. Does anyone know of any
software that will take as input either an HPGL file or a Gerber file and
convert it so that it plots the outlines of the tracks (ie. suitable for PCB
milling ? Have any of you folks used TurboCNC in this way for home brew
millers.

Many thanks in advance folks.. Remove NOSP to reply

Cheers, Doug
 
Douglas Simmonds wrote:

Hi folks,

I am building a CNC type PCB milling machine. Does anyone know of any
software that will take as input either an HPGL file or a Gerber file and
convert it so that it plots the outlines of the tracks (ie. suitable for PCB
milling ? Have any of you folks used TurboCNC in this way for home brew
millers.

Many thanks in advance folks.. Remove NOSP to reply

Cheers, Doug


I do not think you want the outline, as there is no such thing as
having a zero width milling tool - except a laser beam in comparison
with the width of desired cutouts.
Gerber format is good, in that it gives the tool size and the route
(movement) to follow; the resulting cutouts will then look the same as
what one would see with a Gerber viewer or plotted on a film.
As far as i could find, all Gerber viewers require $$ to obtain (if
you want to be able to use them for more than 15 days), and there are
almost no Gerber converters (ore require $$ as mentioned).
HPGL as far as i can determine, give zero info on tool size, and
would seem to be unusable for your purposes.
The Gerber format is well described, so one could write a program for
interpreting to milling requirements.
 
Robert Baer <robertbaer@earthlink.net> wrote:
: As far as i could find, all Gerber viewers require $$ to obtain (if
: you want to be able to use them for more than 15 days) . . . .

Actually, the gEDA Gerber view gerbv is open-source and no-cost. If
you're building your own PCB milling machine, you might be interested
in hacking the code to drive your machine. It's not a complete
solution, but it might be a good starting point.

http://gerbv.sourceforge.net/

Stuart
 
Actually there are a number of free Gerber viewers (without
restrictions), however the problem is that you don't want a
Gerber viewer as a viewer simply views files as the name
suggests.

Gerber format on it's own is not adequate. As mentioned it
gives your route movement and width. However it overlaps those
routes at junctions which would cut your traces at any corner.
Secondly, what you actually want is not the width but an offset
of 1/2 the width plus 1/2 the width of your bit from the center
line of the Gerber aperture. So Gerber on it's own is completely
inadequate except as a starting point for
manipulation/generation/analysis of your actual route path.

The existing commercial applications of this nature use
Gerber as their preferred input format. They then calculate and
generate the actual router paths and output these in a
proprietary format.

--
Sincerely,
Brad Velander

"Robert Baer" <robertbaer@earthlink.net> wrote in message
news:ylSFe.5932$Uk3.5101@newsread1.news.pas.earthlink.net...
I do not think you want the outline, as there is no such
thing as
having a zero width milling tool - except a laser beam in
comparison
with the width of desired cutouts.
Gerber format is good, in that it gives the tool size and
the route
(movement) to follow; the resulting cutouts will then look the
same as
what one would see with a Gerber viewer or plotted on a film.
As far as i could find, all Gerber viewers require $$ to
obtain (if
you want to be able to use them for more than 15 days), and
there are
almost no Gerber converters (ore require $$ as mentioned).
HPGL as far as i can determine, give zero info on tool size,
and
would seem to be unusable for your purposes.
The Gerber format is well described, so one could write a
program for
interpreting to milling requirements.
 
One route worth investigating would be output the HPGL as you'll probably
end up with the outlines of the tracks there. Next get a hold of HPGL2CAD
from GuthCAD in Australia to convert the HPGL to DWG/DXF. You can then load
the DXF file into a cheap CAD package, or AutoCAD, generate some lines which
are offset from the existing ones then save these for milling.

Another route would be to get a CAM editor (like GC-CAM) and use the Gerber
files. Import the gerber files in to the CAM editor, copy the original
layers, change the copied layers to a different aperture table and increase
the apertures of this table, then create a new layer for output being a
composite of the new enlarged layers, plus the original layers as a negative
over the top, therefore leaving you with the outlines. You might be able to
get some output from this that's useable and easily convertable for your
needs.

The long-winded way, if all else fails, of using this output may be to plot
it out, re-scan it in and use some vectorisation software, like CorelTrace,
Scan2CAD, Adobe Illustrator etc. to get back to a vector form.

Anyway, some ideas to start with.

James

"Douglas Simmonds" <douglNOSPas.simNOSPmonds@btinternet.com> wrote in
message news:dc8nql$52p$1@nwrdmz03.dmz.ncs.ea.ibs-infra.bt.com...
Hi folks,

I am building a CNC type PCB milling machine. Does anyone know of any
software that will take as input either an HPGL file or a Gerber file and
convert it so that it plots the outlines of the tracks (ie. suitable for
PCB milling ? Have any of you folks used TurboCNC in this way for home
brew millers.

Many thanks in advance folks.. Remove NOSP to reply

Cheers, Doug
 
OK Folks

Thank you very much for the input. It seems surprising that if you want to
mill a pcb you will need the contour outlines yet none of the hobby level
PCB CAD tools seem to export this. Maybe it is time for me to put on my
programmer's hat and pull out a copy of the Gerber specification !

Many thanks again !

Doug
 
Douglas Simmonds wrote:

OK Folks

Thank you very much for the input. It seems surprising that if you want to
mill a pcb you will need the contour outlines yet none of the hobby level
PCB CAD tools seem to export this. Maybe it is time for me to put on my
programmer's hat and pull out a copy of the Gerber specification !

Many thanks again !

Doug


Gerber is for exposing film to light via defined apertures (size and
shape), and paths are always centerline.
A board outline, even tho it may be expressed in a Gerber file, is no
exception.
 
"Douglas Simmonds" <douglNOSPas.simNOSPmonds@btinternet.com> wrote...
I am building a CNC type PCB milling machine. Does anyone know
of any software that will take as input either an HPGL file or
a Gerber file and convert it so that it plots the outlines of
the tracks (ie. suitable for PCB milling ?
The command-line tool hp2xx will convert HPGL files to a variety of formats,
both vector- and raster-oriented. One of these may be more convenient for
you to deal with.
http://www.gnu.org/software/hp2xx/hp2xx.html
Windows version at http://gnuwin32.sourceforge.net/packages/hp2xx.htm

However, it is not clear why Gerber format would not be suitable. Your
primary task would seem to be to get the originating application to produce
the Gerber files with a constrained set of apertures (i.e. corresponding to
the milling tools you have).
 
"Matthew Kendall" <mdkendall@hotmail.com> wrote...
Your primary task would seem to be to get the originating
application to produce the Gerber files with a constrained
set of apertures.
... and to generate the inverse of the pattern you want, of course. Depending
on the PCB design software you use, that will either be trivial or
impossible.
 
.. and to generate the inverse of the pattern you want, of course.
Depending on the PCB design software you use, that will either be trivial
or impossible.

Exactly ! Generating the photoplots using Gerber I understand completely.
But I need the inverse of the pattern to run a *milling machine* because I
need to mill out the Copper around the plottted tracks !

Doug
 
"Douglas Simmonds" <douglNOSPas.simNOSPmonds@btinternet.com> wrote in
message news:dcgqo6$a2a$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...
.. and to generate the inverse of the pattern you want, of course.
Depending on the PCB design software you use, that will either be trivial
or impossible.

Exactly ! Generating the photoplots using Gerber I understand completely.
But I need the inverse of the pattern to run a *milling machine* because I
need to mill out the Copper around the plottted tracks !
EAGLE can do this natively; run outlines.ulp. This produces an HPGL file. It
is the same problem as flood-filling the layout with ground plane.

Jonathan
 
In article <xrSGe.8404$q23.1374689@news20.bellglobal.com>, Jonathan
Westhues <google-for-my-name@nospam.com> writes
"Douglas Simmonds" <douglNOSPas.simNOSPmonds@btinternet.com> wrote in
message news:dcgqo6$a2a$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...
.. and to generate the inverse of the pattern you want, of course.
Depending on the PCB design software you use, that will either be trivial
or impossible.

Exactly ! Generating the photoplots using Gerber I understand completely.
But I need the inverse of the pattern to run a *milling machine* because I
need to mill out the Copper around the plottted tracks !

EAGLE can do this natively; run outlines.ulp. This produces an HPGL file. It
is the same problem as flood-filling the layout with ground plane.

Jonathan
You can generate an outline-only trace for each routing layer
from Vutrax once you have a finished artwork.
The feature is contained in a groundplane generating facility
selected using
[Outline Etch] from (Tools > Routing > Groundplanes >
Build Rules > Outline Etch)
and can be found in the manual by searching for 'outline etch'.

Once you have the outlines you can output them in any Vutrax PLOT
format which includes HPGL (with controlled pen size), Various
Gerber formats (including ability to work with a single aperture
which would suit milling), various milling specific formats,
bit maps, Postscript etc.

You can download all the stuff you need for Linux or Windows from
http://www.vutrax.co.uk (Main UK site)
http://www.protonique.com/vutrax (Central Europe Mirror)
Free for evaluation and DIY size projects up to 256 pin with
no time limits, no required internet access, or other tricks.
The download includes a full tutorial for schematic through
routing and PCB layout and output.
--
Roy Battell.
To use this address remove the digits included to remove Spam ...
Mail: news@vutrax666.co.uk
 
Matthew Kendall wrote:

"Douglas Simmonds" <douglNOSPas.simNOSPmonds@btinternet.com> wrote...

I am building a CNC type PCB milling machine. Does anyone know
of any software that will take as input either an HPGL file or
a Gerber file and convert it so that it plots the outlines of
the tracks (ie. suitable for PCB milling ?


The command-line tool hp2xx will convert HPGL files to a variety of formats,
both vector- and raster-oriented. One of these may be more convenient for
you to deal with.
http://www.gnu.org/software/hp2xx/hp2xx.html
Windows version at http://gnuwin32.sourceforge.net/packages/hp2xx.htm

However, it is not clear why Gerber format would not be suitable. Your
primary task would seem to be to get the originating application to produce
the Gerber files with a constrained set of apertures (i.e. corresponding to
the milling tools you have).


I agree; Gerber is better in that it specifies aperture size/shape
which can be interpreted as what cutting tool to use.
And this business about "outline" is extremely puzzling.
Any cutting tool other than a lazer will cut "beyond" that line by
one-half of its diameter and so cut beyond the desired pattern as
expressed in the "outline" interpretation of a Gerber file.
 
Douglas Simmonds wrote:

.. and to generate the inverse of the pattern you want, of course.
Depending on the PCB design software you use, that will either be trivial
or impossible.


Exactly ! Generating the photoplots using Gerber I understand completely.
But I need the inverse of the pattern to run a *milling machine* because I
need to mill out the Copper around the plottted tracks !

Doug


NOW we have the required info!
That is a color of a different horse!
And you *still* do not want or desire "outline".
What you want is the *edge* of the cutting tool to follow the outline.
So, if the cutting tool is not a lazer beam then you want to cut
where a "fill" with a given relief would otherwise go.
That relief would be half the cutter diameter.
That means the inner corners would be rounded.
Write the conversion program in PostScript...
 

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