Major Manufacturing's Pit Bull Steel Door Tool Simplifies Hardware Changes

April 1, 2007
One of the more difficult modifications is recessing a latch pocket into a hollow metal door edge to accommodate an auxiliary lock. Major Manufacturing's Pit Bull tool makes this task much simpler.

Most hollow metal doors are factory constructed to accommodate a specific building's hardware requirements. Retrofitting or adding lock hardware can be a time-consuming job. Unlike a wood door, a hollow metal door cannot be easily modified.

One of the more difficult modifications is recessing a latch pocket into the door edge to accommodate an auxiliary lock. Adding a cylindrical deadbolt to a non fire rated hollow metal door has been made much easier with Major Manufacturing's Pit Bull, Model MDLT-1, which is designed to form a latch face pocket into the metal door edge. The deadbolt's latch fits into this recess, keeping the surface of the latch roughly flush with that of the door edge. In this way, using the Pit Bull ensures that even a tight fitting door will not drag because of a surface mounted deadbolt latch. Using a latch face pocket tool to install a cylindrical deadbolt into a hollow metal door will make the finished job look professional.

The Major Manufacturing Pit Bull is comprised of a draw die, forming die and a draw bolt with bearing washer. The draw die has raised edges at the top and bottom into which the forming die and the door edge metal are pressed as the draw bolt is tightened. The draw die has raised edges (ears) overhang on one side. The draw die is inserted into the door cavity with the ears towards the folded side of the door. The opposite side of the door has the welded seam.

NOTE: Major Manufacturing has an 8-32 tapped hole into the rear of the draw die for a screw to secure a wire to the tool. In case the draw die falls into the bottom of the door cavity, the wire can be used to retrieve it.

The forming die has two tipped set screws, at approximately 13/16” from the center of the draw bolt hole. These two setscrews are a guide for the two latch mounting holes. To determine the proper location for the latch face pocket, there are centerlines cut into each side of the forming die.

The draw bolt is equipped with a thrust bearing that makes it easier to apply the necessary turning force in order to form the pocket. NOTE: Major Manufacturing recommends lubricating the threads of the draw bolt with bearing grease prior to installing the Pit Bull fixture onto the door.

The draw die is placed into the cavity against the inside of the door edge and a forming die that is placed onto the outside of the door edge. The draw bolt threads into the draw die squeezing the door edge metal forming it into the pocket. The draw bolt has a .750” diameter thread.

In order to use the “Pit Bull”, the cross bore and edge bore openings must first be drilled. Major Manufacturing recommends installing a deadbolt lock that uses a 2-1/8” diameter cross bore opening. This size cross bore opening makes it possible to insert the draw die into the door cavity.

To create a latch face pocket into the edge of a hollow metal door:

Step 1. Determine the height for the deadbolt.

Step 2. Drill a 2-1/8” cross bore opening and a one inch edge bore opening into the hollow metal door.

Step 3. Draw a horizontal centerline across the one-inch diameter edge bore opening. This line will be used to position the middle of the latch face pocket.

Step 4. Place the draw die into the door cavity with the threaded hole directly behind the edge bore opening. Make sure the draw die “ears” point towards the folded side of the door.

Step 5. Make sure the set screw and the forming die are within the body.

Step 6. While holding the draw die in position, place the forming die against the door edge and thread the draw bolt with thrust washer into the draw die. NOTE: Be sure to lubricate the draw bolt threads using bearing grease. Do not tighten the bolt.

Step 7. Center the tool over the latch hole, not only vertically using the centerline on the forming die, but also horizontally to ensure the latch face pocket is centered on the door edge.

Step 8. To prevent the hollow metal door from distorting, Major Manufacturing includes two steel bars to be clamped into placed onto each face of the door. Use two “C” clamps to secure the two steel bars against each face of the door where the pocket will be formed.

Step 9. Use a 1-1/8” box end wrench to slowly tighten the draw bolt. The forming die will create the pocket in the door edge as it bottoms out against the drawing die. Stop tightening the draw bolt when the forming die bottoms out.

Step 10. Use the supplied hex wrench to tighten the two setscrews in the forming die. The points of the setscrews will locate the position for drilling and tapping the two latch mounting holes.

Step 11. Remove the “Pit Bull” fixture and install the deadbolt according to manufacturer's instructions.

Forming a “Pit Bull” a latch face pocket into a metal door edge helps to ensure that the door and lock will operate properly, while providing the end user with the appearance that the job was properly completed.

For more information, contact your local wholesaler or Major Manufacturing, 1825 Via Burton, Anaheim , CA 92806 . Telephone: 714-772-5202. Fax: 714-772-2302. Web Site: