Sunday, May 29, 2011

Grand Piano Pin Block Support

When driving the tuning pins into a grand piano, the pin block has to be supported from the underside.  The reason for this is the way in which the pin block is manufactured. Generally speaking, the pin blocks in pianos are constructed of multiple layers of wood laminated together.  In modern construction, most pin blocks are manufactured of up to 18-20 layers laminated together with phenolic resins.  In early construction, pin blocks were 3 layers of much thicker materials over a maple plank.
In either case, while stringing procedures are completed, or when the tuning pins must be driven deeper into the pin block for increased torque ratings, the block must be supported from the underside. Without support, the bottom layers of the pin block laminations will be forced apart by the tuning pin being driven into the block from the top. Once this de-lamination occurs, the repair is to replace the pin block, which is a time consuming and costly mistake.
Below is a link for some photos of the traditional way to jack and support a pin block. Of course there are other ways to accomplish this task without the specialty machinist’s jacks; by using a series of wedge planks would be one example.
When jack supporting the pin block this puts excessive pressure on the key bed; sometimes with vintage instruments one does not know how strong the key bed is. In instruments that are older, it is also a good idea at times to support the key bed from underneath the piano to the floor. This can be done with short lumber and a small hydraulic jack.
Below is a link to a  series of photos showing the tools and supplies required for supporting the grand piano pin block.

Monday, May 2, 2011

Piano Action Repairs: Hammer Butt Shoulder Buckskin Replacement

This is one of the common repairs for an upright piano action. As the hammer head, stem, and butt assembly returns after striking the strings, the hammer butt is caught by the back check attached to the whippen assembly. The back check contacts a small stem and buckskin covered wooden plate attached to the rear of the hammer butt. 

 This creates a contact point that has considerable wear; in a piano action where the regulation is neglected, or left out of proper mechanical adjustment, the wear on this point is considerable over time. Once this small piece of buckskin is worn through the wear begins on the original, obsolete wooden parts. 

Obsolete piano action parts are difficult to obtain. At one time there were so many different piano manufacturers, it is impossible for the  piano parts makers to supply  parts with the correct geometric measurements for every make and model of piano produced. The parts suppliers have decided to make generic fit parts. These parts come close to the original and will work properly; sometimes with geometric adjustments to the parts or the action itself.

There is of course, the usual wear that happens with regular use of the piano. This is why it is so important for the older pianos to be kept in proper mechanical adjustment. This is called regulation of the piano action. When the piano action is kept is proper regulation and the felts and buckskin within the action are kept in good condition, very little damage is done to the original wooden parts.

Here is a photo album of the replacement of the hammer butt shoulder buckskin. There is text to read below each frame in the photos.