Therma-Tru SHOP 3 Door Preparation - U1 Revised - Manual (Page 22)

Door
Preparation
3.22 2014 (U1 REVISED) Shop 3
Lock Preparation
90 Minute Steel Fire Door
CAUTION:
Only shops licensed as fire door machiners may perform this lock preparation.
Flip door over.
Align drill with pilot hole
and complete boring.
Drill Crossbore When Door Machine Is Not Available
Bore through half of door thickness until pilot pierces other side.
CAUTION:
Do not bore completely through
to other side of door.