Bending Rims Since the 1870's

Written by Chuck Johnson | Dec 14, 2012 7:16:01 PM

Steinway & Sons pianos have long been considered the best pianos in the world, and while many people know this, not many people know why. Though every aspect of Steinway’s creation process contributes to the magnificence of its pianos, there are a few key features that stand out. In the third part of this series, this we will talk about the rim, and rim bending process and it's importance to the Steinway piano.

Building a Sound Foundation

The rim of a piano is one of its most easily identifiable parts. It is what gives the grand piano its iconic shape, it’s what everyone sees when they look at a piano, and it is the foundation upon which the rest of the piano is built.
Steinway & Sons has always understood that in order to create a quality instrument, they must create a strong and resilient foundation. It is with this idea that they developed their unique rim-bending process in the 1870’s, and they continue to use that same process to this day. To understand the process, let’s look at the parts.

Strength in Numbers

All Steinway & Sons pianos have rims that are constructed of multiple laminations of plain-sawed, hard rock maple. Maple is a wood that can withstand an incredible amount of pressure from the strings, provide a solid and sturdy support for the keyboard and action, as well as accept a finish to become not only an instrument in construction, but a beautiful piece of furniture.
Many wonder why laminations are used as opposed to a solid piece of wood. For one, a solid, knot-free piece of hard-rock maple is virtually impossible to come by. More importantly however, is that the multiple boards, the glue, and the balanced stresses of the grain make up a rim that is stronger than the sum of the parts.

Inner Rim; Meet Outer Rim

There are two rims to a piano: the inner rim, and the outer rim. The inner rim is the base and support for the soundboard, and the outer rim is

Most piano manufacturers approach the creation of a rim very differently than Steinway. They first start with the inner rim by fitting the soundboard to it, and then shape the outer rim around it in a separate procedure. With this method a great deal of structural integrity is lost, resulting in a loss of vibration that translates to a loss of power, sound and quality.meant to contain the vibration of the strings and soundboard, and focus them inward to maximize volume of sound. The outer rim is also the most visually prominent part of a piano, so it functions aesthetically as well as sonically.
Steinway has a different approach to the rim-bending process.

Bending Rims Since the 1870’s

Instead of bending the inner and outer rim separately, Steinway bends both rims together in one unified process. Doing this not only creates a physically stronger foundation, but a sonically stronger foundation as well. The structural integrity of the Steinway rim means that no vibration is lost, therefore maximum power and sound is achieved.

A crew of six workers does nothing but bend rims. The process is a sight to behold both for its impressiveness and meticulousness. Once the wood is prepared (preparation includes laying the wood in a certain pattern, compiling the laminations into a book, and applying a thorough layer of glue) it is taken to the mold. There are various molds for the various sizes, but the process remains the same for each.The operation is one of efficiency, and mastery. The crew has to shape about 400 pounds of maple into a curved rim that defies the nature of wood, and they must do so before the glue sets, which is about twenty minutes. No power tools are used, only brute force and leverage. As the crew bendsand molds the sheet of wood into the shape of a grand piano, one man follows along with a mallet, pounding down the top edges of the laminate to ensure proper alignment. Once the wood has undergone its multiple turns and curves (a few of which are 90 degree curves), the clamps are secured and a low electric voltage is passed through the laminate to cure the glue; a “high-frequency” curing system patented by Steinway & Sons in 1947.

Let the Wood Rest

The rim is left on the mold for twenty-four hours before it’s dated, marked, and moved to a temperature and humidity controlled chamber where it rests for at least ten weeks. This rest period is paramount, as the wood needs to accept its new shape, as well as return to its optimal moisture content.
This process is a hallmark of Steinway pianos, as it is one that requires a level of mastery that can’t be found elsewhere and results in excellence. It is also a more time consuming, and ultimately, expensive procedure. However, it is the superior way of creating a piano rim and Steinway has practiced this method for well over 100 years.
Steinway & Sons pianos hold over a century’s worth of innovations, from the rim-bending process to the Accelerated Action, and they continue to “build the finest possible piano at the lowest possible price.”

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