When punching a hole in sheetmetal in preparation for countersinking, we punch a hole large enough to leave a minimum of. The diagram above demonstrates this.
We have calculated the hole diameter required for a number of popular screw sizes and have listed the dimensions in the tables below. Head Dia. Our standard for the diameter for the top of the countersink is to take the middle of the range for the nominal dimension with a tolerance of plus or minus.
Hole Types (Countersink and Counterbore)
For example for a 8 flat head screw in. Any dimension for the top of the countersink from.
The hole punched in the sheet metal is designed to leave a minimum. This will prevent burr formation on the bottom side of the sheet metal.
For the example above we would punch a. Part of the head will extend below the surface of the sheet metal.
Countersink Holes Countersink Diagram Why our hole diameter is usually greater than the body diameter When punching a hole in sheetmetal in preparation for countersinking, we punch a hole large enough to leave a minimum of. Table for 82 Degree Countersinks Screw Size.
Top Ctsk. Body Dia.