Home Security: Cutting A Deadbolt Hole In A Metal Entry Door

By Bruce W. Maki, Editor

Introduction:

Most new pre-hung doors come with a hole already cut for the lockset (i.e. the door knob). But not all doors come with an extra hole for a deadbolt. When special-ordering a door, this extra hole can usually be drilled for little or no charge, but if a deadbolt is desired for an existing door, then a hole must be cut through the door.

This article describes the procedure used to cut  the standard 2-1/8 inch diameter hole in an insulated steel door. Cutting a hole in a solid wood door is pretty much the same process.

My Project:

I had purchased a door for a project on a friend's garage. My original plan was to paint the door in one of my garages and install the pre-hung unit already painted. I prefer to paint a door laying flat on sawhorses instead of hanging on the hinges, because I can do a much better paint job on a horizontal door.

I separated the door from the jamb by removing the hinge pins. Then I laid the door on a pair of sawhorses in the garage.

This Thermatru brand door was special-ordered through my local Home Depot. This was an out-swinging door for a garage with very limited interior space. I understand that outward swinging doors are not usually stocked by retailers.

The supplier for this door simply maintained a stock of various door blanks. They would punch the door knob holes and mount the hinges upon order. It sounded like a straight-forward process.

However... I ordered this door with a deadbolt hole but the supplier somehow missed the note on the form, and they forgot to punch the extra hole. I got a refund for the $6 extra-hole charge, but I had to buy a special hole saw for this project.

The location of the deadbolt hole.

I marked the centerline for the hole, using the standard 2-3/4 inch back-set employed on the existing hole. I marked the location 4 inches above the main hole.

Note that most locksets and deadbolts come with a paper template that can be taped to the door, but I had not yet purchased the door hardware.

This is the 2-1/8 inch diameter hole saw I bought for this project. It cost about $15.

The hole saw fits on this mandrel, which I already had. This part also cost about $15.

The mandrel screws into the hole saw and then the collar is tightened until the drive pegs (two steel rods) protrude into the smaller holes. Note how the pilot drill sticks out beyond the edge of the hole saw.

The drawback of these heavy-duty hole saws is that they require a ½" drill to turn them. The mandrel has a 7/16" hex base, so the more-common 3/8" drills cannot be used.

I used a nail to make a dimple in the steel. I normally use a proper center punch, but in this case I was too lazy to walk back to the main garage to get that tool, so I just used a nail that was laying around. When drilling steel it's critical to start by making a punch-mark in the metal, otherwise the drill bit will almost surely wander before it starts to cut, and the hole will be hopelessly out of place.

I used my biggest drill to drive the hole saw. It's critical to make sure that the drill shaft is perfectly vertical, or very close. If you are not familiar with hole saws it's important to note that there is a pilot drill that starts the hole (at the punch-mark) and holds the shaft in position as the actual hole saw does the cutting. Using a hole saw without a pilot bit is basically impossible.

I strongly recommend using a drill with a side handle, because if/when the hole saw grabs the metal it will try to twist your arm off.

After I cut through the steel on one side I kept drilling until the hole saw bottomed out on the foam core.

The pilot bit had drilled through the other side of the door, which is what I wanted. Sometimes this doesn't happen, such as jobs where the material is very thick. I flipped the door over and drilled the other side. I simply started the hole saw in the pilot hole I had just punched through.

In about a minute I had cut through the steel and foam, leaving a fairly smooth hole.

I used a round file to remove some imperfections in the edge of the cut. I did this to both sides of the door.

I applied some gray primer (from a spray can) to cover the bare metal. I wanted to make sure that the cut metal wouldn't rust any time soon.

The final step was to drill a 7/8 inch diameter hole for the deadbolt latch. This hole goes in the center of the door's edge (of course) and in line with the center of the larger hole.

The completed hole for the deadbolt. Actually, I forgot to photograph one final step: cutting the rectangular recess for the faceplate of the deadbolt latch.

This was done later. The latch was placed in the 7/8" hole and the outline of the latch faceplate was traced onto the wood. Then a hammer and chisel were used to dig a shallow recess.

Notes:

1. Most deadbolts and locksets come with a paper template that can be taped to the door. This provides accurate layout of the center holes. Of course, marking the holes with a center punch is still necessary. When I cut this hole I had not yet purchased the deadbolt, so I had no template.
2. I removed the hinges from the door and the jambs so I wouldn't get paint on them.

Copyright © 2003  HammerZone.com

Written January 25, 2003