D Code Table - Understanding D Codes Table in GerbView

Hello everyone,

I am having some trouble understanding the d code table that is generated in GerbView. I want to make sure that I have all the right mill ends and was hoping that it cold help.

Here is an example of the table:

*** layer 01 ***
tool 01: D10 V 0.0039" H 0.0039" Round

Any help would be awesome.


Have you loaded the DRL or copper layers ?
For copper layers, flashed D codes can have differing V and H values, being oval/rect pads.
For drill layers, it looks to always be round (V=H) and slots are displayed in GerbView as slots, but using that Drill size D code. (ie excellon has a slot command)
A combination of visual inspect, and D-code check, should confirm

Hey! So everything is loaded and it looks good.

I think I understand a bit better, but I think I’m not too advance yet.

What exactly is d-code? What does D10 mean? V? 0.0039’’ reference to? That kind of thing.

Is there some resource I can use that breaks down the table? I haven’t been able to find anything.

Once again, thank you.

Dnn is simply the D-code (or equivalent, if DRL based)

More is here
https://en.wikipedia.org/wiki/Gerber_format that’s PCB plot traces etc
https://en.wikipedia.org/wiki/Excellon_format that the holes/slots

You can open any Gerber/Excellon file with a Text editor, to see the info.

When you load a Drill file, GerbView maps across the Drill tools, to an equivalent Gerber D code and shows as the true-size dots.

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I’ve been reading through it and its starting to make a bit of sense, however I’m still held up on what exactly the V and H values are. Are they vertical and height of the mill?

I opened the gerber file in notepad and went through it. I’ve included a image as well.


Also, in case anybody uses this later, I found this and its been helpful:


Again, thank you for all the help. I’ve been learning a lot and everything is starting to click together.

Not quite. V & H are Vertical / Horizontal, but ‘mill’ is not quite right.
Gerber files are intended for photo-imaging, not milling, so you may mean DRL files ?

As you can see, Oval and Rect shapes (usually) have different V,H, so for those the Flash D code includes the pad-shape.
However, if you load a Drill file with slots, there are no ovals in the GerbView D-code mapping of the tool(drill) sizes.

There, the GerbView has used a round equivalent to display the Slot, and dragged it internally.
The NC machine at your PCB fab does the same, ie it can understand Slot info, in the drill file.

We have also supplied Gerber special-layer plot files, intended for milling long PCB edge slots, and the PCB Fab manages the conversion to Excellon that their machine needs. Choose line-widths that match their slot mills.

The Gerber shows the round-tool-end, exactly as a finished slot will have.

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