Best practice for creation of separate milling layer

Done a few designs over the last half year in KiCad. Also just upgraded to the latest 5.1 version. Great stuff. So far I have not looked back at eagle.

However, with my most recent design I ran into the requirement for a separate milling layer for various cutouts within a larger board. Manufacturer seemed to have trouble with extracting the already present information from the edge cut layer.

For the time being, what would appear to be best practice to generate an additional file containing only milling information?

There should an added milling layer capable to blend together with the edge cut layer in Pcbnew and the 3D viewer. Perhaps something like this is already in the works.

Otherwise great work. Two thumbs up.


Sorry for the ignorant question, but what would the difference between a milling layer and the Edge.Cuts layer would be? Everything except the board contour ?

Some manufacturers can handle internal slots (cutouts) in the Edge.cuts layer. Some want them in another layer. it’s also possible that plated and non-plated slots are different. That would be logical because they are not physically processed at the same time. It’s a reasonable requirement that plated and non-plated routed slots aren’t mixed into one layer (like plated and non-plated holes are in two different files by default).

Just yesterday I missed basically the functionality which @jos requested, namely that the extra milling layer would be visible in the 3d view. Now I just have to dedicate one of unused layers to that information and rename the gerber file. I had the lines duplicated in Edge.Cuts so that the slots were visible in 3D. I deleted them before generating gerbers.

Plated vs. non-plated is a bit problematic because you can’t make plated slots with zones if edge.cuts is used because zones have clearance. For plated slots you have to use another layer for the routing edge or something else than copper zone (pad, graphic polygon?). As far as I know manufacturers handle the routed (or drilled) edges as plated if a copper feature is on top of it.

Technically it is indeed the same thing, though some manufactures prefer a separate file containing just milling information since it can be a different processing stage. Drilling an milling are not necessarily done at the same time on the same machine.

Some manufacturers apparently are set for extracting milling information from the edge cut layer without extra charge.


Meanwhile the manufacturer in question apparently managed to extract the milling information. Board already in production.

Essentially there needs to be added an additional layer for milling, and perhaps then some more layers for all kinds other things.

E. g. an extra milling layer as in eagle, though that sure is not enough reason to deploy eagle. KiCad largely hits the spot so to say.

Yes, using one of the extra layers is an option though error prone due too much extra file handling like renaming etc. Good enough for one offs and definitely not recommended where every board needs to be a ‘hole in one’.

A milling layer sounds like a feature request if not done so already.


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