I picked up about a dozen mid-to-large-sized screw on Metolius holds off kijiji and I want to convert a few to bolt-ons. I figure bolts will make it easier to turn them and move the holds around as needed. Does anyone have any experience doing this? They are not urethane, but rather the older, heavy resin style like these:
My plan is to drill a 5/32" hole all the way through with a masonry bit, then widen part of that hole to ~5/8" for the first 1/2". I'll glue a 3/8" washer in the countersunk portion to accept a standard socket cap screw.
Is this a good plan or will I break the holds somehow? Should I drill a pilot hole with a thinner bit first?
Feedback, advice, and spirited disagreement welcome.