When attaching a metal hinge to plastic, you need to ensure that, if the plastic part becomes damaged, you can remove the hinge from the plastic. Two methods allow you to attach a metal hinge to plastic. Both methods use a hole drilled into plastic for a fastener and the decision on which method of attaching the hinge to the plastic you use will depend on the strength requirements of the hinge.
Things You'll Need
Plastic part or sheet
#7 drill bit designed for plastic
9/32-inch drill bit designed for plastic
Variable speed drill motor
Tee-handle tap wrench
1/4-inch machine screws, lock-washers and nuts
7/16-inch ratchet wrench
Place the plastic part or plastic sheet on the work table. Ensure that if you are attaching a metal hinge to a plastic sheet, you do not remove the protective coating from the surface of the plastic.
Cover the side of the plastic part or sheet that the metal hinge(s) will attach with masking tape.
Stretch the tape measure along the plastic part or sheet and place a pencil mark at the location you will be mounting the metal hinge. Repeat the process if you are installing multiple hinges on the plastic part or sheet.
Align the metal hinges on the marks you made on the plastic part or sheet and mark the holes of the hinge on the surface of the plastic with a pencil.
Put on your safety glasses.
Secure the #7 drill bit into the chuck of the drill motor for the 1/4-20 tapped hole or a 9/32-inch drill bit for the 1/4-inch machine screws.
Place the tip of the drill bit onto the surface of the plastic, aligned with one of the pencil-marked hinge holes.
Pull the trigger of the drill motor and, with slight pressure, drill the hole through the plastic part or sheet. Continue drilling the remaining pencil-marked hinge holes.
Insert the 1/4-20 tap into the tap-tee handle if you are tapping a hole for the 1/4-20 bolts or skip to step 12 if you are passing a machine screw through the plastic part or sheet.
Align the end of the 1/4-20 tap with one of the holes, ensure that the tap is straight with the hole and turn the tap tee-handle clockwise to thread the #7 hole. Repeat the procedure to tap all the drilled holes in the plastic part or sheet.
Set the hinge onto the plastic sheet with the holes of the metal hinge aligned with the tapped holes in the plastic, thread a 1/4-20 bolt into each tapped hole and tighten the bolts with the 7/16-inch ratchet wrench to complete the installation of the metal hinge to the plastic part or sheet.
Slide a 1/4-inch machine into each 9/32-inch hole you drilled through the plastic part or sheet.
Place a lock-washer and nut on each 1/4-inch machine screw and turn the nut clockwise to tighten the nut to the bottom surface of the plastic.
Set the 7/16-inch wrench onto the head of the machine screw and slide the 7/16-inch ratchet wrench onto the nut located on the other side of the plastic.
Turn the 7/16-inch ratchet wrench clockwise to tighten each bolt, securing the metal hinge(s) to the plastic part or sheet.
Lubricate the drill bit with water while you drill through the plastic to make drilling easier and the finished hole shiny.
Do not overtighten the fasteners to the plastic part or sheet, as this can cause the plastic to crack.