The Glossary

Some technical terms defined

Illustrations by Arno Ghelfi

March 2013

Bounce

The amount of space between the leading edge and the groundline when the club is in the square address position. In general, more bounce is better for soft sand and lush grass; less bounce is better for firm sand and turf.

BULGE

The face curvature from heel to toe that corrects spin on mis-hits.

CAMBER

The radius measurement of the sole from front to back or heel to toe.

CAST

A way of manufacturing a clubhead by pouring molten metal into a wax mold.

CENTER OF GRAVITY (CG)

A theoretical point that defines the average location of weight in a clubhead, or the internal point about which the club rotates.

A low CG helps to launch the ball higher. It isn't always found at the geometric center.

COEFFICIENT OF RESTITUTION (COR)

The measurement of springlike effect of a flexing clubface. The USGA limit is .83, which means that if a ball is projected at a club at 100 miles per hour, it must bounce off at 83 mph or slower to conform.

CUBIC CENTIMETER (CC)

The unit of measurement for clubhead volume.

CUPFACE

In this construction, a club's faceplate is part of the front of the crown, sole and skirt. This pushes the weld farther from the face, allowing the face's perimeter to be thinner.

FLANGE

The part of a putter that projects back from the face.

FORGED

A way of making a clubhead by heating metal and then stamping it into shape.

MOMENT OF INERTIA (MOI)

The measure of a club's resistance to twisting on off-center hits that's sometimes equated to forgiveness.

The USGA limit for drivers is 5,900 grams/cm².

Polymer

A synthetic material that is lightweight, resilient and can be engineered to meet a range of hardnesses.

relief

An area on the sole where material has been removed, often with a grinding wheel, to decrease turf drag.

steel types

The name refers to the amount of trace elements present: 17-4 stainless has a high chromium content to resist rusting; 303 is malleable to permit custom bending. Carbon steels are better for forging.