Re: Drilling through hard old Wood Joists/Lathe
My suspicion is that not only is the wood extremely old, dry, and hard, it has a good amount of sand embedded in it from the plaster, which will take the edge off a drill bit in short order. You might try using a pilot point or brad point drill bit. Both of these will still dull quickly if you're drilling through sand, but the design of the bit will still allow for cutting where a standard drill bit won't.
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