Keeping a freezer closed completely is key to its operation. One way to insure that it is closed after every use is to add a hasp that fastens the door in the closed position. Chest freezers are typically made from a medium thickness of sheet steel that is easily penetrated by a self-tapping sheet-metal screw. The aggressive threads on these screws will hold the hasp securely in place and makes installation a simple process. Proper alignment to make sure the hasp does not hinder the freezer from closing completely is the most important factor.
Separate the hasp into its two pieces. One is typically four to six inches long, with a smaller mounting plate hinged to the hasp, or tongue of the latch. The second piece is typically a small square plate with a flat metal tab protruding from it, with a hole in the center for a lock. This tab is known as a staple. Latching varieties have a toggle mount under this tab that allow it to be twisted, latching the hasp in the closed position.
Align the small plate about 1/3 of the way across the width of the freezer from one corner, on the edge of the lid. Center it on this edge from top to bottom. Mark the screw holes in the plate onto the freezer. Drill shallow 1/8 inch pilot holes in each marked location. Align the plate with the pilot holes in the freezer lid, under the screw holes in the plate. Drive one ½ inch self-tapping, pan head, sheet metal screw into each hole using a cordless drill with a Philips bit.
Fit the latch slot of the longer hasp tongue over the tab of the small plate. Fold the hinged portion of the tongue under, as it will be on the freezer when installed. Position the tongue on the face of the freezer where it will rest. Adjust the height so that the slot in the tongue fits neatly over the tab without pulling it down or pushing it up. Mark around the square bottom end of the tongue onto the freezer's face with it held in this position.
Fold the hing open to reveal the screw holes and align the bottom of the hinged portion with the outline you just made, double check the fit with the tab if you are unsure and adjust as needed. Mark the screw holes in the smaller mounting plate, hinged to the hasp tongue. Drill 1/8 inch pilot holes as before and mount the tongue with one screw in each hole.