What size drill bit should i use for a pilot hole for a 1/2 " lag screw?
Question:
Answers:
a 3/8" pilot hole for soft woods.
a 7/16 pilot hole for hard woods.
A 1/4 inch would do, a 3/16 inch if you have it.
You didn't say how much weight the screw will be holding but the largest bit you should use would be the same size or smaller than the main shank of the screw. Probably 3/8" since the threads are probably 1/8" more than the shank. This would give you full bite and prevent splitting of the material you are screwing into.
A size smaller to give the lag holding power.
Lag screws are no designed to need a pilot. If you do use one, smaller than the screw that you are using.
a way to call a bit size is to place the drill bit ontop of the screw and see if the drill bit is just wide enough to cover the screw's shaft and not cover any of the screw's thread.
ps 3/8
3/8
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I like to use 3/8:" pilot using an electric impact driver, easier than using socket wrench..
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