I drew a cutout, than I reflected it and than I selected both holes and tried to reflect them again...
Didn't work.
Ofcourse I could use a hole feature. But I didn't to illustrate the problem. This happens all the time. Solidworks refuses to pattern things, especially fillets and chamfers.
You could try using a circular pattern to get the second set of holes (2 instances, 180 degrees apart). You may have to turn on the "Geometry Pattern" option to get it to work.
Mirroring a chamfered hole twice works for me. From your screenshot I think your problem is that in the second mirror you didn't select the original hole as one of the mirrored features, you only selected the chamfer. Try again where you select the original hole, the chamfer, and the first mirrored hole.
Or maybe I don't know which is the original hole. I thought it was the top left one. Can you attach the part?
This helped me with a circular pattern. Thank you!
https://www.youtube.com/watch?v=bRpqiRbS46s
I have some Solidworks 2014 interface problems...
I will try to select things in the right order but chamfers and fillets always cause trouble.
As a rule it has been suggested that it is best to do chamfers and fillets last to avoid most problems. This isn't always possible but it does help me.
A mirrored fillet or chamfer has to land on the same face as the seed feature.
It's a pain in the butt, but it's as-designed behavior.
There are only 4 edges in question, so I'd just chamfer all of the holes after creating the mirrored features.
On a more complex part you have to get clever with your feature order and use of symmetry