Piano World Home Page Forums Our Most Popular Forums Piano Forum Wet Sand Casting versus "V-Pro" Casting for Piano Harps

Yamaha makes its own frames, relying on a method of casting referred to as the “vacuum process,” developed over many years to create some of the best piano frames in the world. During this time we have built up a storehouse of knowledge on factors such as the manner in which controlling the temperature and composition of casting, and even the coating used on the frame itself, affects the acoustic characteristics of the piano.

Here is the info for sand cast plates used in Essex grand pianos

"Designed by STEINWAY & SONS, the plate is cast from gray iron and over engineered to provide strength to support 20 tons of string tension. Long-fiber cast iron creates a very dense plate, which does not absorb energy and yields a fuller tone."

Link to relevant webpage:
https://www.bostonpianos.com/pianos/essex/grand/egp-155#82118b76-7607-41b9-9894-e0cc9aad510e

agree to disagree

Don is correct I have never visited a V-process foundry. I have visited a wet sand foundry.

I do have extensive experience machining and filing piano castings, probably more than any other technician since I pioneered reshaping V-bars to a true V-shape around 1977. Feeling how cutting tools interacts with a material give insight no book "learnin" can give.

Don is either ignorant or eliding the significance and variability of the practice of the post casting case hardening methods often applied to the V-bar feature by some piano makers. A very slight difference in case hardening level has a profound affect on tone, tunability and string longevity. This is a powerful indicator that metal hardness of the plate is very significant. It is a significant reason some pianos sound so much worse than others in the same production run.

I have studied the material science regarding this issue and have as a regular visitor to my shop the recently retired chief material scientist of the Boeing company. I have discussed the issues of the metals used in pianos at great length and nothing I have said here is outside the science. My friend has taken samples to the Boeing test lab to help me.

I also suggest to you all that you investigate the significance of longitudinal modes and how the nature of the plate metal and termination points affect their ability to be propagated and coupled to the "normal" transverse modes.

I also urge you to consider how the abrasive nature of a string bearing point affects the behavior and durability of piano wire. Consider that the bulk of the strength in piano wire is in the skin. Just nick the surface of piano wire and slightly bend it at that point a few times and it will break. It is important that the deformation the termination point imposes on the wire does not reduce the break point to the elastic limit of the undeformed wire.

It may well be possible to make a V-process plate that performs as well or even superior to a wet sand cast plate.

But so far my experience with plates that are V-process is they have tone and string durability issues. The same thing can be said about wet sand plates that have highly case hardened U-shaped V-bars.

You can also feel the problem in the way the strings render when tuning. They "stick" to the V-bar and even "ping" when they finally move when tuning.

Folks, I gotta tell you most all piano made or being made have less than ideal string terminations on the plate. The problems extends to agraffe string hole shape as well. In my view this is gross negligence. I have been practicing and preaching this for decades, anybody listening? Anybody care? Or is piano making one big idiotic artsy fartsy fraud.

...before anyone says "what about the V bar" - that's a finishing detail, not a fundamental aspect of the fabrication technology.

Is a scientific explanation or empirical data available to justify or validate the string breakage claim?

Well I've had my Yamaha S7X about 3 months or so, and already all of the treble strings above C6 have snapped clean off! It doesn't bother me that much as I don't really use that part of the piano anyway. The bass strings are intact, which is the main thing.

I'm not sure that Yamaha and Kawai owners are experiencing a problem with frequent breaking of treble strings. Are you sure you're not getting carried away?