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ToMetric 1.0 for Dos
This program converts CAD or Gerber files to metric
Roman Black - April 2004 - web Aug 2006.

What is it?

If you use a CAD program or a PCB design program the output files are usually in "Gerber" text file format. These files are then sent to a production firm to make your PCB. Most PCB production firms and SMD placement firms now insist on metric file data.

If you have a combination of older (imperial) CAD components and newer SMD etc components (metric) ToMetric 1.0 scans through the text (Gerber) file and any imperial data is changed to metric. Metric data is not changed, nor are comments etc.

How to use it

Win98; Go to Start->Programs->MS-DOS Prompt
(WinXP; Go to Start->Programs->Command Prompt)

Navigate to where ToMetric.EXE is, then run the program this way;
TOMETRIC [filename]
where [filename] is the name of the Gerber file.

Obviously it helps if ToMetric.EXE and the file are in an easy to find directory like C:\ root directory. The input file is NOT changed, instead the data is written to a new file with the SAME NAME but a .MET extension.

After metric conversion is complete, ToMetric gives an on-screen report (like the one shown above) showing how many data items were converted and if there were any items too large to be converted.

The Results

Before: (A sample from input file Thefile.WHL)
D122     draw      0.012in
D123     rectangle 0.900mm x 1.300mm
D124     rectangle 1.0524mm x 1.4524mm
D125     octagon   0.063in
D126     round     0.063in
D127     draw      0.001in
D128     octagon   0.066in
D129     rectangle 0.028in x 0.056in
D130     rectangle 0.034in x 0.062in

After: (A sample from output file Thefile.MET)
D122     draw      0.305mm
D123     rectangle 0.900mm x 1.300mm
D124     rectangle 1.0524mm x 1.4524mm
D125     octagon   1.600mm
D126     round     1.600mm
D127     draw      0.025mm
D128     octagon   1.676mm
D129     rectangle 0.711mm x 1.422mm
D130     rectangle 0.864mm x 1.575mm

Metric data was left unchanged, but any imperial data was converted to metric.


It is a Dos program. (But should work under all Windows versions) It is functional enough for the times I need it and there is little point turning it into a Windows program when it works ok under Windows anyway.

It only converts imperial data that is X.XXXin.
It won't convert anything over 9.999in size, but it will put a little comment on the end of the line and gives an error report once the rest of the file is converted. Data items over 9 inches are very rare in PCB files!

Obviously you need to re-name the output file after conversion is finished. Generally PCB manufacture firms require file extensions to suit their equipment and you need to re-name the Gerber files anyway.

Sorry it only converts imperial to metric and not the other way around! Metric is the way of the future and the language of miniaturisation, especially now with the rapid growth of Asian chip and discrete component fabs and the boom in SMD components in general. That old inches ruler belongs in a museum!

Download it!

ToMetric 1.0 for Dos (also works under Win95, Win98 and WinXP)

It is Hippyware which means you can use it for free for personal or corporate use and you only pay me IF you choose. Payment is $10 USD or a postcard etc.

The ZIP file below contains these files:
  • ToMetric.EXE
  • Sample.WHL (sample Gerber file)
  • ToMetric.htm (these html instructions)
  • Tomet01.gif
  • Tomet02.gif

    Right-click HERE to download ToMet10.ZIP (38 kb).

    - end -

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