Therma-Tru SHOP 3 Door Preparation - U1 Revised - Manual (Page 20)

Door
Preparation
3.20 2014 (U1 REVISED) Shop 3
Lock Preparation
(Except 90 Minute Steel Fire Door)
Drill Crossbore When Door Machine Is Not Available
Bore through half of door thickness until pilot pierces other side.
Flip door over.
Align drill with pilot hole
and complete boring.
CAUTION:
Do not bore completely through
to other side of door.