Residential & Commercial Security - Locks, Keys & Dead Bolts - Help Changing out a Deadbolt Lock

I'm changing out an old deadbolt at a friends house and ran into an problem I can't figure out how to solve.

The new deadbolt needs a 2" hole in the door where the old deadbolt had a 1.5" diameter. The door is a metal exterior door with a foam core and I can't seem to get a normal hole drill bit to cut into the metal door. The other issue is that since the hole is already cut for 1.5", there is nothing in the hole to keep the 2" hole bit in place to make the cut anyway. Is there a special tool for cutting a bigger hole in a metal door when a smaller hole already exists?

Thanks,
Chris

The simple fix here is to clamp two pieces of wood (larger than the existing hole) over the inside and outside of the door...then measure and drill with correct size holesaw.

Your alternative could also be...to remove the 2" plate on the back of the lock cylinder (some of them come off) this will allow you to fit the lock without requiring the modification.