Set of panels with mechanical positioning means

A set of rectangular building panels having a frontside and a backside, comprising a mechanical locking device at opposite first and second edge portions configured for plane locking of similar panels in an assembled position by displacement of a plane with a second edge portion of a second panel in an engagement direction towards a first edge portion of an adjacent first panel, the plane locking including locking along a plane of the frontside,

• wherein the first edge portion comprises a first locking element configured to cooperate for plane locking with a first locking groove at the second edge portion,
• wherein the first edge portion has a first front edge portion adjacent the frontside of the first panel and a first sub edge portion between the first front edge portion and a flexible tongue in an insertion groove, the insertion groove being arranged between the backside of the first panel and the first sub edge portion,
• wherein the first front edge portion provides a plane perpendicular to the plane of the frontside, and the first sub edge portion is arranged as a tongue between the first front edge portion and the insertion groove,
• wherein the second edge portion has a second front edge portion configured to be in contact with the first front edge portion in the assembled state of the panels, the second edge portion further having a second sub edge portion configured to be positioned opposite the first sub edge portion in the assembled state, the second edge portion further having a protrusion arranged between the second sub edge portion and the backside of the panel,
• wherein the protrusion is configured to cooperate with the first sub edge portion during assembling of the opposite first and second edge portions,
• wherein a first distance between a first plane of the first front edge portion of the first panel and a second plane facing said first plane and in line with a front edge of the first sub edge portion is equal to or larger than a second distance between a third plane of the second front edge portion perpendicular to the frontside of the second panel and a fourth plane parallel to said third plane and in line with a front edge of the protrusion of the second edge portion, and
• wherein the flexible tongue is configured to cooperate with the protrusion during assembling.