Manually Adding Tool List for a Drill File
PCB NC drill file
Figure 1. A sample NC drill file with some explanations
Drill files do not contain the tool list
Not every PCB design software generates drill file in a proper format. Some older software separates the drill information into two files. One contains holes' XY coordinates, and the other (Generally it’s a free format human-readable file) contains the tool size and other information. At JLCPCB, we expect the NC drill file to be completely self-contained, so the CAM operators don’t need to re-enter these information manually (This process may introduce errors).
Common drill file issues:
- The header is incomplete (Sometimes there is no header at all)
- The tool list is missing
- The unit is unspecified
- Zero suppression information (LZ/TZ) is unspecified
Let’s see some examples.
Below is a drill file generated by PCB Wizard, tool list is missing in the header:
M48 % T01 X04450Y03150 X04450Y03050 X00350Y01950 ... M30
Below is a drill file generated by Wintek’s HiWire, it has the wrong header format:
/*****************************************/ /* NC Drill Data from Wintek's DT.D */ /* Format: Inches; 2 integer, 3 fraction */ /* digits (leading zeros included) */ /* HiWIRE reference datum: 2784, 1700 */ /* (derived from board extents) */ /* Date: Sun Sep 05 14:21:52 2021 */ /* */ /* Tool Usage Summary: */ /* Tool No. Diameter Count */ /* -------- -------- ----- */ /* 1 0.020" 686 */ /* 2 0.030" 4 */ /* 3 0.032" 33 */ /*****************************************/ % G90 T1 X05230Y03557 X05179Y03422 ... M30
A drill file by some version of Protel, no tool size:
M48 T01F00S00 T02F00S00 T03F00S00 T04F00S00 T05F00S00 % T01 X01474Y02177 X01483Y02398 ... M30
Add the tool list
To correct the drill file, first we need to find the Drill Tool file which contains the tool size information, such as this one:
DRILLING PROTOCOL OF 'XXX.CNC' 10.09.2021 17:18:50 THIS IS FREE TEXT TOOL COUNT DRILL TYPE DIAMETER PATH LENGTH 1 87 1 0.45MM 58.31 cm\n 2 111 3 0.79MM 66.37 cm\n 3 64 4 0.90MM 50.44 cm\n 4 4 14 4.00MM 25.40 cm\n ...
Suppose the following is the corresponding Drill Location file:
T01 X04450Y03150 X04450Y03050 X00350Y01950 ... M30
Now, open both of them in a text editor.
To create a tool definition entry, just simply add letter T before the Tool Number and letter C before the diameter. Other text can be deleted directly.
For example, TOOL 1 to 4 will be converted to this form:
T1C0.45 T2C0.79 T3C0.90 T4C4.00
Copy and paste this list into the header of the Drill Location file. If M48 and the % sign do not exist, just add them. Ta-da, a decent drill file is born!
M48 T1C0.45 T2C0.79 T3C0.90 T4C4.00 % T01 X04450Y03150 X04450Y03050 X00350Y01950 ... M30
Unit and zero suppression
Some softwares will provide the drill sizes in different units, if the Drill Location file is in metric (mm), the drill sizes should also be in mm. If the drill Location file is in Inch, the drill sizes should also be in Inch. Just do the conversion accordingly.
In the following Drill Tool file, the unit of drill diameters are in th (i.e. mil):
NC Drill Setup Format: ASCII, 2.4, imperial, absolute, eob=<CR><LF>, no zero suppression. Notes: Tool sizes are diameters. Layer sets are in brackets - 0=TOP, 15=BOTTOM, 1-14=INNER. T01 157.4th (0-15) T02 60th (0-15) T03 30th (0-15) T04 45th (0-15) T05 40th (0-15) T06 50th (0-15)
When we do the conversion, we need to convert mil to inches, (simply divide by 1000), so the above list will be converted to the following list:
T01C0.1574 T02C0.060 T03C0.030 T04C0.045 T05C0.040 T06C0.050
If the unit and zero suppression information is provided in the free text Drill Tool file, just add them after M48, for example:
M48 INCH T01C0.1574 ...
Note If you don't know these info, just don't add them. Our CAM operators will try to figure them out.
Excellon 1 VS Excellon 2
There are actually two Excellon formats, the older Excellon 1 and Excellon 2. By default, we assume the file is in Excellon 2 format. If you know your file is in Excellon 1, you need to tell us this explicitly (Write a special instruction when you place the order).
If an Excellon 1 file is recognized as an Excellon 2 file, errors will occur, for example, extra holes may occur on the PCB, etc.
1. "PCB NC formats". Wikipedia.
2. "XNC format specification". Ucamco.
3. "EXCELLON FORMAT SPECIFICATION". GithubGist.
Last updated on Oct 27, 2022
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