Max Knives MKRB6-10 — 10 mm ball bearing, 6 balls, 4 mm bore

Overview

The MKRB6-10 is a ball bearing sold individually for rebuilding a folding knife or smoothing its action. It shares the MKRB6-9's 4 mm bore, 4 mm thickness, six balls and 1 gram weight; only the outer diameter changes, taken up to 10 mm. It is the part to reach for when the recess in the liner gives you that extra millimetre.

The bore has to match the pivot

Of the three dimensions on a bearing, the inner diameter is the unforgiving one: it is where the knife pivot passes through. Here the bore is 4 mm, so it calls for a 4 mm pivot. A thinner pivot lets the bearing sit off centre and the blade picks up play; a thicker one simply will not go in. On a stripped knife, take the measurement on the body of the pivot screw, not on its head, which is always wider.

Technical specifications

Ball bearing, reference MKRB6-10, sold individually. Outer diameter 10 mm, inner diameter 4 mm, thickness 4 mm. Six balls. Weight 1 gram. A workshop part for rebuilding a folding knife or smoothing its opening action. It shares its 4 mm bore, its thickness and its six balls with the MKRB6-9, differing only in outer diameter.

Care

The bearing goes into a clean recess on a degreased pivot, with a drop of fine oil to start it turning. On reassembly, tighten the pivot screw gradually: too tight and it crushes the balls against the races and stiffens the action; too loose and the blade floats. The right setting is found in small quarter turns, testing the action between each one.