Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Brackets on the "Catcher shank"

Hello colleagues,
I discovered these brackets in a modern Bechstein piano with Renner mechanics.
About 90% of the tones were provided with it. What is the point?

They look like Bulldog clips with the wire parts removed! I'm guessing in an attempt to add some mass to the action?

These are a type of paper clip that has had the wire handles removed after the clip was placed on the catcher dowel. This added mass will alter the center of gravity, (CG), of the hammer assembly so as to add more return force to the hammer.

This altered CG will reduce the tendency of a vertical piano action to suffer from "baubling" hammers. This baubling is when the hammer can't return from the string fast enough during soft playing resulting in double strikes with one key stroke.

The added mass will also dull the tone especially in the top three octaves.

I have found it best to narrow the hammers to reduce the mass always be combined with the addition of a catcher counterweight like this.

Vertical actions on this size piano also often suffer from inadequate return CG in the whippen. The slightest sluggishness in the whippen center pin bushing can cause the keys to stick.

Ed, I'd love to hear more about your hammer narrowing technique. I am working with a Petrof P125 right now with slight baubling during soft playing and would like to know more about reducing hammer weight, if that is indeed the issue.

Somehow it's as if to say "Bechstein/Renner got it wrong"......

I am quite certain the clips are not original. It is a technician's "fix" for a perceived problem. Sometimes, a "fix" addresses the symptoms but not the actual problem.

Many newer vertical pianos exhibit the baubling hammer with soft playing problem. Especially in the tenor hammers just above the bass break.

The issue is the center of gravity of the hammer butt assembly allows too little return force. These action were designed to use lighter hammers than most makers are producing today, and heavier hammers tips the action over into problem CG behavior.

The simplest approach is to reduce the width of the tenor/treble hammers. This will lighten the hammers and make for more positive hammer return force.

You do need to remove all the butts from the action to sand the hammer sides with a disc sander. You must be careful with your fingers. And you must use calipers to help you remove a consistent amount from the hammers.

Some techs have fixtures for their table saws that will trim the sides of the hammers. But if the hammers are angled to meet the sweep of the strings, it takes great care not to sand the shank.