Safe edge of a file tool is one which is not having any teeth's cut on it.

During filing, sometimes the metal chips (filings) will clog between the teeth of files. This is known as ‘pinning’ of files.
Files which are pinned will produce scratches on the surface being filed, and also will not bite well. Pinning of the files is removed by using a file brush also called a file card, with either forward or backward stroke.

To prevent the hacksaw blade binding when penetrating into the material, and to allow free movement of the blade, the cut is to be broader than the thickness of the hacksaw blade. This is achieved by the setting of the hacksaw teeth. There are two types of hacksaw teeth settings.