Down Bearing... What's That?

29/08/14 14:06

Down bearing is the pressure that the strings push down on the soundboard. We control this by adjusting the height of the bridge on the soundboard to the plane of the piano string. First, the plate is lowered in the piano, then measurements with a thread are taken often as we move through the length of the bridge.

In the pictures below, you will see references created by making notches in the bridge. This is done slowly for each reference to achieve the proper distance between the top of the reference and the bottom of the string.
Once the references are created, the bridge is planed down smooth. Graphite is put on top of the bridge, then the bridge is punched, knotted, and drilled. New bridge pins are then installed.
Kurtzmann restoration

The Plate is now going to be re-bronzed and the pin block is fitted and drilled. Once that is complete, the next step will be to secure the plate to the piano and prepare to install new strings.

Kurtzmann restoratoration photo

Let's Glue It All Together

28/08/14 13:53

It is now time to glue it all together.
Kurtzmann restoratoration photo

Kurtzmann restoratoration photo
Above, you will see pictures of the bass bridge and the cap of the treble bridge being glued together.
Below is a picture of a new hybrid pin block gluing together. What makes this a hybrid, is a mixture of a very dense pin block material called Delignit, glued to a traditional maple pin block. The 6mm of Delignit help give extra support to the pin as it enters the pin block, resulting in less flagpole and an excellent consistency. These are an absolute pleasure to tune for the technician. For the customer, the tunings produce great results.
Kurtzmann restoratoration photo

Now we need to glue the bridges to the soundboard

Now that we have te bridges glued to the soundboard, we are going to refinish the bottom side of the soundboard with the ribs. Then, we are going to glue the soundboard to the inside rim of the piano.

Kurtzmann restoratoration photo

Bridge Work

10/07/14 13:51

Once all of the old bridge pins are taken out, the old bridge cap is removed. This leaves the bridge root and holes from all the old bridge pins. These holes are filled to prevent problems while drilling in the new bridge cap.
The short bass bridge had a damaged apron. This was duplicated..
Kurtzmann restoratoration photo

Now Its Time to Glue Ribs to the Soundboard

10/07/14 13:46

The next step in our restoration will be to glue the ribs to the soundboard. The trick is to have constant pressure throughout the entire length of the rib. We use air through a fire hose to accomplish this task with about 45psi.
Kurtzmann restoratoration photo Ct

Rib Selection and Design

25/06/14 13:45

After removing the old soundboard and cleaning all the old glue off the mortises, Its time to fit the ribs. In this piano, we selected sugar pine in the bass end of the piano for flexibility and Spruce ribs in the treble to drive the higher frequencies.
Kurtzmann restoratoration photo

The ribs are then cut to support the crown of the soundboard and fitted to the piano. A flatter radii is used in the bass to promote flexibility and progresses to tighter radii as the ribs reach the treble. To recap, everything selected here is to promote flexibility in the bass and stiffness in the treble.
Kurtzmann restoratoration photo

The soundboard panel is roughly cut, using the old panel as a guide. Then, the panel is fitted to the case of the piano. Once that is achieved, the long side of the soundboard to around the nose is diaphramed. (tapered thinning on the the outside edge) This again, helps promote more flexibility in the bass. The panel is placed in the piano and the rib positions are marked.
Kurtzmann restoratoration photo

RSS Feed