| Symbol | qFs |
|---|---|
| Unit | mm |
| Attribute-ID | undercut |
| Numeric ID | 4212 |
| Value Type | PMTechValue |
A root undercut is an intentional undercut (e.g. with a protuberance tool) of the profile of a tooth flank in the area of the tooth root. The amount of the root relief qFS is the largest distance between the tooth root fillet and the imaginary involute below the root form circle. Below the base circle, the involute is replaced by the connecting line between the center of the gear and the involute origin point.
See ISO 21771 2014 section 6.1.1