It is not fun to deal with knobs and pulls with stripped threads so that the knob or pull come off of the drawer or door when grasped, yet it happens frequently.
Many at Instructables have dealt with this often in their time. This is for the person who has the problem, but does not know what to do about it.
Step 1: The problem and one solution
The threads strip out in the first 1/8 inch or so of the threaded post on the backside of the knob or pull. Many simply insert part of a paper matchstick into the hole and twist it back onto the screw. This may last for a very short time, but eventually fails.
Step 2: The real solution
The entire length of the post on drawer hardware is threaded. Push a toothpick into the hole and pinch it with your fingernail to indicate the length of the threaded portion inside the post. The distance from where your fingernail pinches the toothpick to the end of the toothpick is the ideal amount of threads to extend beyond the finished surface of the cabinet wood. You really want to shorten this distance by about a millimeter or two in order to allow a little free space for tightening the knob on the screw. Add to the amount of thread extending beyond the finished wood surface the thickness of the cabinet door or the drawer front. You may also need to add the thickness of a washer. See the next step.
Step 3: Small head?
The screwhead on the left is the screw removed from the knob or pull. The screw on the right is a standard screw from the hardware store. Notice that its head is smaller than the original screw. Adding a washer gives it better support against the wood on the back side of the door or drawer front and is a good idea, but it also adds a little thickness that needs to be considered in preparing a screw for your knob or pull.