Why the TouchRail works so well – More than just “lighter touch”

All grand piano actions are heaviest in the rest position and get lighter as the keys are depressed.    The fly and knuckle directions aren’t aligned at rest (left),  but converge toward nearly perfect alignment at the point of escapement (right). This normal condition exists  in even the finest and best prepared pianos.

But when an action is burdened with excessive weight (heavy hammers, for example) or incorrect geometry,  touch weight can easily become too heavy,  especially in the beginning of the keystroke.  The TouchRail, in contrast, produces an assisting spring force which is strongest in the rest position and diminishes as the keys are depressed.  It’s like a key lead that gets smaller as the key goes down.  A TouchRail produces a smooth, consistent keystroke that requires less force to get started.

And when compared with supplemental key leads, or reduced hammer mass, a TouchRail preserves  significantly more upweight and low key repetition function.

Try this easy experiment

Insert shims between the back rail and key of a grand action, measuring static down weight after each shim. A dramatic reduction in down weight will always be observed through the pre-escapement key stroke.

Less slope = better control When these measurements are charted for both an original key (blue) and the same key with an applied TouchRail (red), an interesting pattern is revealed.

The original key is clearly much heavier, especially at the beginning of the key stroke. But the TouchRail curve also shows noticeably less change in resistance (slope) as the key is depressed.