Helilap Bore Finishing Tools

For extreme accuracy in production bore finishing, there is only one way to guarantee precision. This involves a Helilaps and an abrasive lapping and polishing medium or Kemet Diamond Compound.

Manufactured from a uniform grade of annealed, close grained, grey cast iron, the lap incorporates a unique helical slot and external circumferential grooves. When the lap is slipped over the arbor and tapped gently with the lap expander, the internal taper in the lap and the taper on the arbor make contact, therefore allowing a precise degree of diametrical expansion to be achieved uniformly over the entire lap. This means that a Helilap gives a fast lapping action, perfect for bore roundness, exceptional straightness and superb surface finish. They are produced in a large range of sizes from 3/64" dia. to 3" dia as well as metric sizes.

Helilap Design

The Helilap, made of a good quality, close-grained, lapping iron has a tapered bore to enable it to slide on a high-tensile, hardened and ground steel Arbor. When the lap is driven up the Arbor, expansion occurs, and by utilisation of uniform points of contact around the circle, the roundness of bores and diameters can be held to extremely fine limits. Also, because the points of contact extend on the circle through the length of the lap, parallelism can be guaranteed. The lap will contract on being pulled down the slope of the Arbor but this contraction is limited and care should be taken in selecting the correct lap size. After use the lap should be removed from the Arbor so that it "relaxes" back to its original state.