Precautions for the Use of Flat-head Screws

1. the hole-expanding cone should be 90 degrees, to give assurance, would rather be less than 90 degrees, and not more than 90 degrees this is a key trick.

2. if the thickness of sheet metal is less than the thickness of the head of the head of the sink screw, you can change the small one screw, or would rather expand the hole smaller also can not expand the hole so that the bottom hole diameter becomes larger caused by the part pressure is not tight.

3. if there are more than a sink screw hole on the part, processing to be more precise, once drilled crooked, assembly is difficult to see, but as long as the error is not completely can be tightened, because when tightening, if the diameter of the screw is not very large (about 8mm), the hole gap error, the screw head will be tightened due to force and deformation or tight.