Simple 90° Countersink Calculator made using (html, css, js) was originally made as an enhancement for a tool a friend made who actually works in the sheetmetal industry if you can relate please feel free to use & modify it to your liking.
A countersink is a cutting tool, which cuts a conical hole into an object. The most popular application for countersinks is to de-bur an existing hole to allow a bolt or screw to sit flush against the workpiece surface. Countersinks can also be a convenient tool for removing burs left over from drilling or tapping applications.