The anchors are 8mm diameter so I need to make an 8mm hole through the door frame to accommodate them. The problem is that the hole will go through the steel frame inside the plastic frame as well and I'm not sure whether I should start with an 8mm HSS bit and just try to make the hole in one go, or would it be better to use a pilot HSS bit of smaller diameter first to stop the larger 8mm bit wandering?
Anyone have any experience of doing this? What should I do?
Thanks for any advice.