Pilot holes in MDF

[larry cronkite]

I am installing a woodworking vise going thru 3/4" hardwood into 2-1/4" MDF using 3/8" X 3" lag bolts.

What size pilot holes should I drill in the MDF?

[Dave Trask]

Personally, I would use though bolts washers and nuts if at all possible.

[John Keeton]

Same here! I wouldn't ever trust mdf to hold up to the stresses of a vice, and the constant movement with lag bolts. It may work, but why worry about it when through bolts would work better.