- firstly there’s there resistance as the drill sits on the outer epoxy layer before it gets through
- then it’s turning through the two layers of carbon and turns of carbon come out
- then the drill falls through the adhesive laminate layer really easily (it’s partly air)
- then the drill hits the aramid and stops dead. It can’t cut its way through, it has to abrade its way through. eventually. The picture above is actually a hole I’ve cleaned up as best I can with a new stanley knife blade, which blunted in no time.
If you try and go through too quickly with something like a pointy grinding stone you introduce too much heat and delaminate the layers.
Still, it’s done now and in: