Manually Adding the Tool List

Some older CAD programs separate the tool information into two files. One file contains hole locations, and the other contains the tool size information. We expect the Excellon/NC drill file to be completely self-contained, so we don’t automatically look for a tool list file.

Our site will detect and reject drill files that don’t contain tool size information, so in the case of split files, you shouldn’t be able to accidentally place an order.

Example Files

Drill Tool Information

Since these files are often “human readable” files, they vary significantly in how they’re presented. Typically, they’re presented in a table format similar to this one.

# Tool code   Size (inches)    No. of holes 
T1            0.0300              13
T2            0.0350             200
T3            0.1181               6
Drill Location File
%
T1
X009421Y004444
X007221Y006645
X008715Y005151
T2
X009280Y000526
T3
X011065Y000526
X003475Y002192

Combining the Drill Files

To correct the drill file, use a text editor to open both the Drill Tool file and the Drill Location file.

To convert the human readable drill header to a NC Drill format, you’ll need to use the following NC Drill lines:

  • M48 which indicates the start of a header.
  • T<toolnumber>C<toolsize> which indicates declares a tool size.
  • %, which indicates the end of the drill header, and start of the drill coordinates.

To create a tool definition, you simply use a T and C command in sequence. As an example this line

T1            0.0300              13

will be converted into

T1C0.030

Some tools will provide the drill sizes in different units, typically mil. To convert mil to inches, simply divide by 1000. For example, a size of 300 mil would equal 0.300 inches

Example NC Drill file

After all conversions are done, you should wind up with a single file in this format.

If your Drill Location file is missing the % between the drill header, simply add it in.

M48
T1C0.0300
T2C0.0350
T3C0.1181
%
T1
X009421Y004444
X007221Y006645
X008715Y005151
T2
X009280Y000526
T3
X011065Y000526
X003475Y002192

Metric Drill files

Generally, this is not a major concern: Most tools that cannot produce combined drills will also only produce Imperial/Inch units.

However, you can use one (or both) of the following commands to handle Metric data

  • Adding METRIC into the header causes all tool sizes to be interpreted as millimeters
  • Adding M71 into the header causes the drill location data to be read as millimeters

This example shows a simple fully-metric file

M48
METRIC
M71
T1C0.254
%
T1
X009421Y004444

Additional Notes

In many cases, tools with these issues may also encounter other format errors regarding how to read the provided hole locations.

If you encounter these issues, see the Design Tool Help page for your tool, or see our Common Drill Issues for identifying problems.

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