Do it backwards and save you some unneeded engineering aspects. Bore the
larger hole 1/4" bigger than the intended washer first. Make yourself a
countersink jig to maintain the same depth. Then drill the smaller hole to
run the lag bolt in. I'd go with a 1/4" bit for the 3/8 bolt, and 5/16" for
the 1/2" bolt. You don't need a particular bit type to make the hole, just
be sure its long enough. You might clamp the timbers in place while
"James" < email@example.com> wrote in message
No one has mentioned one key item about your project. Since you said that
the timbers are pressure treated I would assume they are the newer type that
requires either hot dipped galvanized or stainless fasteners. I would also
use the same material for the washers. The new pressure treated lumber eats
regular metal fast. In my area most PT lumber is some type of pine from the
south east part of the states. Running the screw threads on a bar of soap or
wax ( beeswax the best) works very well for installing the screws also.
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