This post (the last entry) may help explain in more detail: https://numericalinnovations.freshdesk.com/support/discussions/topics/14000003635
Thanks for sending the files. DFM Now! "Auto-Loads" all files correctly except for the small non-plated drill layer with 2 holes - Why?
Here's the problem: NC Drill files (and many Gerber files) have a critical flaw because they do not state their zero placement in their header, and leave it up to the CAM tool to guess the appropriate zero placement used for the drill. So for example without knowing the zero placement, the resulting value could be any of the following:
X011114Y035927 <---- Sample Coordinate Definition from your your Drill file
X=1.1114 Y=3.5927 (If Leading zero is 2 with trailing of 4)
X=0.11114 Y=0.35927 (If Leading zero is 1....)
Auto Loads means that the CAM tool must guess all the format settings for each Gerber and Drill file. The benefit of the "Auto-Load" feature is that you don't have to do anything but select a folder -- the CAM tool will automatically detect all required scaling units, zeros placement, & then import all gerber, drill files, etc. 99% of the times all CAM software using some type of "automated import" feature, must first import the drill files and then "guess" the appropriate scale based on the size compared to the Gerber files.
The problem is during "Auto Load" DFM Now! loads all the files simultaneously and that one drill file only contains 2 holes (located closely together). DFM Now! compares the extents of that drill layer against your PCB and assumes that it has incorrectly loaded that drill and scales up by power of 10X.
Here's the following proposed solutions:
1. You can Auto-Load and then perform Drill import (menu: File | Import | Drill...) for that specific layer. See tutorial below:
2. We could add an option in Settings... to "De-Activate AutoLoad Detection" which means whatever import settings are assigned during Auto-Load will be kept regardless of the result (kinda defeats the purpose of Auto-Load).
3. Add those non-plated holes to a single drill file, and inside DFM Now! go to the NC Tools table assign the tool used for non plated drills as "Non-Plated".
We will of course see what else we can do to improve Auto-Load, and use your sample file as a test case.
Thanks again for sending a sample file.
Ok I have the same issue ... and the solution worked. My question is --- how does this happen? The procedure I used to generate the drill data was identical to the method I've used many times before without this problem. The only thing difference I can see with respect to the particular board, is that it is smaller than usual --- only one inch by a half inch or so. Is this a bug or is there something I must be doing slightly differently --- because it drove me crazy until I came to this forum answer.