"Existential Angst" wrote in message
...
Snip


And what diameter would that be, since lags are tapered? And if there
were such a diameter, you would mean "root diameter" or minor diameter --
right?


I have never seen a tapered lag screw unless it was "very" short, and the
diameter you are looking for is the "body" diameter as described by
McFeeleys screw sizing chart.


Altho ahm no 'spert on wood, I doubt that the pilot hole should be exactly
a root diameter (if there were one) for wood. After all, yer not tapping
the wood like metal.
Mebbe there is a woodworker's equiv to Machinery's Handbook that has this
spec -- heh, mebbe even Machinery's handbook has it!

Actually you do want the pilot hole the same size as the body diameter.




I'm sure there has to be some compression of the wood fibre, for adequate
strength, when drilling pilots. 1/8" actually sounds about right.

You only want the threads cutting into the wood, 1/8" is too small.