DXF2GBR Engine

Flashing Circles

Many AutoCAD designers use either circles or "donuts" in order to create circuit board pads in Gerber. The DXF2GBR engine has a way of converting circles and donuts into Gerber flashes.

AutoCAD Circletest example

    This test file has two circles - one of diameter 0.650 and one of diameter 0.300. It also has a donut of outer diameter .110 and inner diameter 0.00.




How to Find the Circle/Donut Sizes

The first step in "flashing" circles and donuts is to obtain a list of the unique sizes that are used in the DXF file. This is done using the scan function -cscan as shown below:

a2g501.exe circletest.dxf -cscan circletest.cir

Upon opening the circletest.cir file one will see:

#
# Round
#
320:0.65
320:0.3
#
# Donut
#
320:0.11,0
#
# Polyline
#
320:0.055

The report shows that there are 320 0.65 diameter circles and 320 0.3 diameter circles. There are also 320 donuts with outer diameter=0.11 and inner diameter = 0.

You can also see that there are 320 polylines with width 0.055. This is because AutoCAD really does not have a donut entity. Although the user specifies an outer dia., inner dia. and center point to create a donut, AutoCAD actually stores the donut as a polyline arc with width that is 1/2 of the difference between the outer and inner diameter.




Adding the Matching Apertures to the APT File

In order to get these circles and donuts flashed, one must first make sure the in the .apt file there is a corresponding aperture defined for each unique size. In the aperture file below, we added three apertures: D12 for the .650 circle, D13 for the .300 circle and D14 for the .110/0.00 donut.

APTUNITS mm
FORMAT 4.3
SUPPRESS LEADING
SUPPRESS CR
CIRCULAR on
GBR_END M02
TEXT D10
LINE d10
ARCRES 9
FONT C:\Program Files\AutoCAD 2002\Fonts\romans.shx
FONTDIR C:\Program Files\AutoCAD 2002\Fonts
CIRANG 360
ABSOLUTE on
FTEXT 50
D10 0.005000 d Round 0.005 0.005
D11 0.01 d Round 0.01 0.0000000
D12 C_6500 f Round 0.6500000 0.6500000
D13 C_3000 f Round 0.3000000 0.3000000
D14 D1100X0000 f Donut 0.1100000 0.0000000




Updating the .CIR File to Map circles to Flashes

The last step is to update the .CIR file which was created by the -scan option. After each entry in the Round/Donut section that you want flashed, you must append the Block Name and the D-code.


BEFORE UPDATING .CIR                 AFTER UPDATING .CIR
--------------------                ------------------------
#                                     #
# Round                               # Round
#                                     #
320:0.65                              320:0.65@C_6500:D12
320:0.3                               320:0.3@C_3000:D13
#                                     #
# Donut                               # Donut
#                                     #
320:0.11,0                            320:0.11,0@D1100X0000:D14
#                                     #
# Polyline                            # Polyline
#                                     #
320:0.055                             320:0.055

After each entry that you wish to flash add the ampersand "@" sign followed by the block name created in the .apt file, separated by a colon ":" and then the D-Code. Then run the engine as you normally would. No additional command line options are needed:

The Batch File: 
C:\WCAD\ASM501\a2g501.exe "@C:\test\circletest.rsp" 0
 
The Response File
"C:\test\circletest.dxf" MM 0.001 "@C:\test\circletest.lst" 1 -z -nlnk -t1 -on10,10 -c:0 "-cfg:C:\test\circletest.apt"

output Gerbers with circles and donuts flashed.

If you wish to duplicate this experiment with the file used in the example you can download them here. circletest.zip 14KB



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