This document, titled "World-Wide Technical Reference Guide: Grand Regulation," provides a comprehensive guide for regulating grand piano actions. It outlines a series of steps and specifications crucial for optimal instrument performance, emphasizing the interconnectedness of various regulation procedures and the need for repeated adjustments to achieve stability. The guide also acknowledges that specifications may vary within reason to accommodate individual player needs.
Function Description:
The device in question is a grand piano action, a complex mechanical system that translates the player's key presses into hammer strikes on the strings, producing sound. The manual focuses on the regulation of this action, which involves fine-tuning various components to ensure precise and consistent performance across the entire keyboard. Proper regulation is essential for achieving a controllable stroke of the hammer, consistent power, good repetition, and a responsive touch.
Important Technical Specifications (as per the manual):
- Blow Distance:
- Models SMLOAB: 1-3/4 inches
- Models C D: 1-7/8 inches
- This is the distance the hammer travels from its rest position to the string, measured from the bottom surface of the string to the top of the hammer head. It is adjusted by rotating the capstan screw.
- Let-Off (Escapement):
- Hammer escapes no less than 1/32 inch and no more than 1/16 inch from the strings.
- This adjustment ensures absolute freedom of the hammer during its contact with the strings, critical for both soft and loud playing.
- Hammer Drop:
- Hammer should drop no more than 1/16 inch from the point of let-off.
- This is the first escapement of the "double escapement" action, set to avoid double striking of the hammer.
- Key Dip (Naturals):
- Factory regulated at 0.400 inches for all grands.
- Acceptable range: 0.390 inches to 0.420 inches.
- Key dip represents the key's full depth of travel.
- Aftertouch:
- Normally 1/16 inch to 3/64 inch, or approximately the thickness of a new penny.
- Aftertouch is the amount the key travels past the point of let-off, influenced by key dip, blow distance, and key level.
- Backchecking Height:
- Hammer is "checked" as high as possible, consistently across the keyboard, approximately 1/2 inch from the strings.
- This ensures the backcheck "catches" the hammer, allowing the fly to return easily for another strike.
Usage Features (Regulation Procedures):
The manual details several key regulation procedures:
- Regulate Fly Position: Adjust the fly's position so its far side aligns with the far side of the knuckle insert. This is critical for a controllable hammer stroke, preventing premature escape (loss of control, power, misfire) or excessive friction (poor repetition).
- Regulate Balancier Height:
- Initial Adjustment: With hammershanks lifted, adjust the balancier height so its top surface is slightly above the fly's top surface. This eliminates lost motion and aids fly return.
- Final Adjustment: Ensure the fly returns correctly when its tender is depressed and released, with a slight drag as it passes under the knuckle, causing the hammer to "wink" (referred to as "rolling the flies").
- Regulate Blow Distance / Set Hammer Line:
- Set Guides: Adjust the first and last hammer in each section in the piano by rotating the capstan screw.
- Make Hammer Line: On the bench, adjust remaining hammers in each section to form a consistent line. This affects aftertouch; lowering the hammer line decreases aftertouch, while raising it increases aftertouch.
- Adjust Let-Off (Escapement): Adjust the let-off button so the hammer escapes within the specified range from the strings. This is crucial for controlling soft playing and maximizing power, ensuring the hammer's absolute freedom during string contact.
- Regulate Hammer Drop: Adjust the hammer flange drop screw to set the hammer drop within the specified range from the point of let-off. This prevents double striking.
- Adjust Key Dip:
- Set Key Dip on Naturals: Use a touch block to guide the adjustment of key dip by adding or removing paper punchings under the front rail cloth punching. Ensure consistent key dip across naturals.
- Set Key Dip on Sharps: Duplicate the "amount of aftertouch" from the naturals, ensuring sharps do not "bury" below naturals when depressed.
- Adjust Aftertouch: Adjust key dip to set the aftertouch on naturals, then duplicate on sharps by feel. Verify fly (jack) travel for free movement between the fly and stop felt when the key is fully depressed.
- Regulate Backchecks:
- Square the Backcheck: Use parallel pliers to square the backcheck to the hammer tail, preventing excessive wear on the hammershank bushing and backcheck leather.
- Align the Backcheck: Use wire-bending pliers to vertically align the backcheck to the hammer molding.
- Regulate Backchecking Height: Adjust the backcheck head angle by hand so the hammer is "checked" as high as possible, consistently across the keyboard.
- Check for Clearance: Ensure the backcheck is not too close to the hammer tail, preventing interference during hard blows or when rocking the key and hammer head simultaneously.
- Set Repetition Springs:
- Check Spring Strength: Strike the key, allow the hammer to catch on the backcheck, and observe the hammer's rise as the key is slowly released.
- Increase Spring Strength: Remove the spring from under the balancier spring grub with a hook, pull it upwards, then reinsert.
- Decrease Spring Strength: Remove the spring from under the grub with a hook, deflect it downwards, then reinsert.
- The spring strength should be adjusted so each hammer rises steadily, quickly but not snappily, with slower speed in the bass and progressively faster in the treble to accommodate different hammer masses.
- Adjust Keyframe Shift Screw: Rotate the keyframe shift screw (located on the treble side of the rim in the keyboard cavity, or in the treble keyblock on older Steinways) to ensure that when the keyframe is shifted, the hammer misses the left string of the trichords. This allows for tone color variation or a full shift.
Maintenance Features (Implicit):
The manual itself is a maintenance guide, providing the necessary steps for technicians to regulate the grand piano action. It emphasizes:
- Regular Checks: The need to perform or check "Grand Preparation" steps prior to regulation.
- Repetition of Operations: Since individual regulation steps affect others, repeating operations is necessary to achieve stability.
- Tool Usage: Mentions "common regulation tools" and specific tools like a "spring hook" and "wire-bending pliers," implying the need for specialized equipment for these tasks.
- Parts Availability: Notes that "Spring tools are available from the Steinway Parts Department," indicating the importance of using correct parts and tools for maintenance.
- Visual Aids: Suggests using the keylid as a backdrop and a straightedge as a horizontal guide for setting the hammer line, and a gauge to confirm let-off settings.
- Consistent Force: Advises using consistent force when checking key dip to ensure accurate measurements.
- Keyblock Security: States that keyblocks should be firmly secured before measuring and adjusting key dip.
The document serves as a critical resource for piano technicians, enabling them to maintain and optimize the intricate mechanics of Steinway grand piano actions, ensuring a high level of performance and responsiveness for musicians.
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