It is amazing how many professionals use a battery powered drill motor at full power with no clutch to install screws into the door or jamb securing door hardware. We see the result: butt and continuous hinges with mangled screw head drives that are not flush or even fully installed. The drive is the machined opening the screwdriver or driver tip enters.
Phillips head screws are not one size fits all. Even though the screwdriver is designed to slide out of the drive when excess torque is applied, using the wrong size screwdriver can really destroy the drive.
When the wrong size screwdriver is used, the edges of the Phillips drive are rounded over as the driver spins when it is not completely threaded. (See Photo 2). This is why it is difficult to remove screws; the screwdriver has nothing to grip.
A more serious problem that often results from overdriving screws is the damage to the wood, metal or aluminum onto which the screws secure the hinge or door hardware. This is because the screws no longer have solid attachment as the treads strip.
When the threads strip less holding force is available. This can result in a door dragging or being out of square and not closing under the power of a door closer.
For practical examples, look at painted hinge screws in Photo 3. Notice only the bottom screw is almost the original shape. The remaining Phillips Head drives have been damaged to varying degrees. The damage was not sufficient to prevent the screws from securing the hinge to the jamb.
Phillips screwdrivers come in five sizes, #000 to #004. For our purposes, screwdriver sizes #002 and #003 will accommodate most common sized Phillips screws used to install door hardware. Use the proper size Phillips Screws to ensure the drive is not damaged. (See Photo 4).
Use the #002 screwdriver for Phillips head screw sizes 5, 6, 7, 8 and 9.
Use the #003 screwdriver for Phillips head screw sizes 10, 12, 14 and 16.
If the screwdriver is too large, it will not seat into the screw's drive. If the screwdriver is too small, it will not fill the drive.
For locksmiths, these retention problems usually occur to hinge screws and hardware mounting screws where more than one screw is installed in close proximity. When screws no longer stay in place, there are several methods of repair.
When working with a wood door or jamb, remove the damaged screws. Insert a piece of wood into each opening and install new screws using a screwdriver to ensure the screw seats properly. For hollow metal and aluminum doors, a fix would be to install a replacement screw that was one size larger. However, the larger screw has a larger screw head. For the head to be installed flush requires enlarging the opening to compensate for the larger sized head. There is a better fix.
Several companies offer oversized repair screws. These screws have a one size larger thread then the head size. For example, a #12 Phillips Flat Head (PFH) has a #14 thread. This way when the screw is installed, the head size is the same.
GKL Products and Major Manufacturing offer oversized repair screws through locksmith distribution channels.
For this article, we will repair a continuous hinge installed onto a wide stile aluminum glass door and jamb. (See Photo 5). The repair will be made using the Major Manufacturing Locksmith Screw Assortment Oversized Repair Screw Kit, part number LSA-3. (See Photo 6).
The installer was in a hurry as more than half of the screws had their drive damaged. Many were drilled off center and angled, and a significant number were not even completely screwed in. (See Photo 7).
The damaged screws were removed using a screwdriver where possible and locking pliers where necessary. The Major Manufacturing LS-31 #12 Phillips Flat Head Screws with 14-24 thread Tec-Point in black zinc were installed in place of the original screws.
Major Manufacturing offers their oversized repair screws as both machine screws and wood screws in different finishes. The machine PFH screws are available as a #8 head with a 10-32 thread, a #10 head with a 12-24 thread, and a #12 head with a 14-24 thread. The wood PFH screws are a #12 head with a 1-3/8" x #14. See Photo 8.
The screws are available in packages of 25 or 100 or as part of a kit, LSA-3 Locksmith Screw Assortment - Oversize Repair Screws, that contains the above screws in different finishes, a 10-32 tap and a #21 drill bit.
GKL Products offer a self-tapping, self-drilling #14 machine screws with a #12 head to replace #12 machine screws.
For more information, contact your local locksmith distributor or:
GKL Products, P.O. Box 533, Herald, CA 95638. Telephone: 888-446-4337. Web Site: www.gklproducts.com.
Major Manufacturing, Inc., 1825 Via Burton, Anaheim, CA 92806. Telephone: 714-772-5202. Web Site: www.majormfg.com.
