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Info: nc drill files (AKA Excellon drill files) specifications available


Hi All,

Finding understandable specifications of drill files in "Excellon"
format, also called NC drill files is not an easy task.
Currently there is no freely available document.

A document about specifications for ECAD tools like Kicad is now
available here:


It was written from the experience of a few organizations that wrote
software (CAD and CAM) to work on these drill files.

Because Kicad is one of organizations that worked on this document, it
can be published on the Kicad site.

For those who do not know the NC drill files specifs, this is a short an
easy to read document.
This is especially interesting because oblong holes were never really
clearly defined.
They are now defined in this document.
(Users who have designed boards using oblong holes know what kind of
issues these holes create)


1- Pcbnew can create drill files in NC format and Gerber format.

2- Ucamco is the owner of the Gerber format.
It is not the owner of NC format, only the owner of this document.
The document was written to help guys who use NC drill files (guys who
write software to create and read these files, and of course other users)

Jean-Pierre CHARRAS