TO DRIVE IN

To drive in refers to the action of assembling two parts by force-fitting, without screws or glue, by exploiting the elasticity and tightness of the materials. The fit between the two components — a reaming slightly smaller than the arbor or the pin intended to fit into it — defines a tightness calculated to the nearest micron according to mechanical fitting standards. Under the force exerted by an appropriate tool — lever stake, micrometric stake, driving press equipped with a set of drifts and stakes — the male part penetrates the female part, slightly deforming the contact surfaces, creating a solid and, in principle, permanent mechanical connection. Driving in is used in particular to set jewel bearings bearings into the bridges and the main plate, to fix a wheel on its Pipe or a pinion on its Arbor, without resorting to riveting or brazing. The driving-in force must be adjusted precisely: if insufficient, the part comes loose during use; if excessive, it cracks the housing or deforms the driven-in part, particularly when it is a fragile jewel. Calibrated tools, fitted with depth gauges, allow control of the travel and pressure applied during the operation.