The silicon bronze screws that I am using are great for corrosion resistance but not really that strong. There is the risk of breaking them with a screwdriver bit. When I am re-attaching the planks after epoxy encapsulation this starts to happen as the solvented epoxy dribbled into the screw holes has toughened up the bore hole. Once this happens a couple of times I start to use wax to lubricate the threads – but am stuck with some broken off screws below the level of the plank. How do I solve this problem?
I’m sure that there are lots of different ways to do this but I used the ‘roll pin extractor’ method. I filed the corner off a roll pin suitable for the thread of a #8 screw so that it can ‘bite’ into the back of the thread (see picture below if you don’t know what a roll pin is), lock it into the chuck of my drill and drill it ‘around’ the broken screw. When I get to the bottom of the screw thread I retract the roll pin and the screw is extracted – captive inside the pin.
Here is the offending item once extracted, minus it’s thread.
The hole is then plugged, re-drilled and a new screw inserted. As the hole made by the roll pin is smaller than the head of the screw the re-bore is completely invisible. Here is the hole after the screw has been extracted – but before it has been plugged.
