Drill, Mill, Cutout from Eagle to Gerber

[Duke]

Hello!
i'm designing my first "serius" pcb that is quite (small 16x36 mm) and it is a replacement for an existing board, therefore the dimension and the shape are fixed and it is not something i can change

i'm using Eagle and i'm ready to send the gerbers to the fab.

as you can see in the attached image (the grid is in mm) the shape have cutout on the corners (because in the existing enclosure, there pass the screws)
plus it has a hole in the top center and four "slots" on the sides of the hole (in cyan in the picture)

currently i've placed the "slots" on the milling layer (46) in eagle

i would ask if it is the intended way to do this or if it is better to draw the outline of the slots on the dimension layer (20) or it is irrelevant?

these slots have to be from side to side. The top of the pcb will not have copper that touches the edge of the slots but the bottom side will have copper till the edges, as i have to be able to solder the thing that will pass through these holes

am i doing it in the correct way?

thanks for all the help i'm receiving on this forum!

[Duke]

i've done several trials, and eagle's drc complains if i draw outline of the holes in the drill layer for example, because they are inside or too near to a track, so i think the milling layer is the right one...

[Cupcakus]

Every fab house is different, but the layer you put it on doesn't matter much.  When you export the gerbers in Eagle you can specify which layers go in which file, ask the fab what gerber file they want your internal routes to be on and just export the layer there.

[rachaelp]

Speak to the fab house you are using and ask them how they want the information specifying, otherwise you might not get what you want.

Some fab houses that let you submit EAGLE boards online allow you to specify cutout areas as part of the process. For example, I put a board with a cut out through Eurocircuits a while back and once I had uploaded my .brd file I could go into the job and click on the areas where the cutouts should be and tell it they were cutouts right there online. In my case I had the cutouts specified in the dimension layer but I think milling would have been fine too.

Best Regards,

Rachael

[Duke]

thanks, I would like to use seeedstudio's fusion service as fab
i'm still waiting reply from them about the milling specs
anyone has experience with this fab ?

I've drawn the cutout outline using a thin but not zero line (as I've seen in other providers spec for milling, for example oshpark.com that it is preferred, plus adding the cut out indication on the same layer)
I've also added the text "cut" inside the area that should be removed, again on the milling layer (the slots are very small and I cannot fit the "cut out" word, I hope this would not cause issue)

is it better to add the "cut" indication on another layer?

I've understood that usually the fab uses the outline on the milling layer (considering the center of the line regardless its width) to calculate the path of the milling machine that will in turn create the hole.
is my understanding correct?

does anyone have other advices for a noob like me ?

thank you!

[Cupcakus]

The word cut is likely fine, hopefully the fab house will get back to you about it.  If you have to use more words than will fit inside the cutout you can just put them outside it with an arrow.  Just make sure it doesn't overlap the cut area anywhere.  Using different layers won't help as the gerber file will merge all the layers anyway.