Category Archives: Piano Technology

Stieff Bridge and Soundboard Repairs

Woodwork repairs to soundboard and bridges is complete.

If you are curious about grand piano construction and would like to better understand the terms used here, you might want to refer to this article.

I removed the bass bridge cap with the plunge router and cleaned up with a hand plane. I installed a new quarter sawn rock maple bridge cap of uniform thickness. I then hand planed the bridge cap to achieve the original height of the bridge above the bass apron.


Technique for the treble bridge was somewhat different. The hide glue joint of the original bridge cap easily separated from the bridge with some prodding from a 1-1/2 chisel. This resulted in no tear-out of the underlying bridge. I flattened the underlying bridge with my 15″ flat sanding block. This was a light operation which simply prepared a fresh gluing surface by removing the crystallized surface of the old hide glue. The existing bridge cap was not of uniform thickness. To duplicate this varying thickness in the new bridge cap, I prepared two sections of bridge cap which I tapered to the correct end-to-end thickness on the joiner. That was tricky work, but I satisfactorily achieved tapered thicknesses within a tolerance of 0.1 mm. I cut curves on my blanks to match the curvature of the bridge, leaving 3-4 mm overlap. After gluing, I trimmed the bridge cap with a flush-cutting router bit. These caps were installed about 0.4 mm over finish height. I hand sanded to finish height with the hand sanding block.

Cracks in the soundboard were repaired using two techniques, depending upon the size of the crack. For the larger cracks, I enlarged the cracks, not by cutting and removing material, but by compressing the fibers of the crack edge into a V-shape for insertion of a V-shaped spruce shim. I made these V-shaped enlargements by inserting the 1-1/2 inch chisel into the crack and then giving the chisel one or two sharp blows with a light mallet. I continued this for the length of the crack, then reversed the orientation of the chisel for a return trip up the crack to complete the V-shape. Prior to gluing the shims, I spread the crack some more by placing upward pressure on soundboard ribs below with props. This had the effect of producing slightly more crown in the soundboard while gluing up. Once the shims were glued and inserted, I removed props which were pushing the ribs upward. This caused the shims to be more tightly bound. Once the glue dried, I flushed the shims to the height of the soundboard. My preferred tool and and technique was simply to hand plane to the soundboard surface. At some points along the case edge and bridges this was not possible. In those cases, I cut them flush with a Japanese flush-cutting saw. I then scraped to the final surface level.

I opened the smaller cracks with the blade of my Japanese flush-cutting pull saw. This essentially used the first two or three teeth of the saw as a chisel of less than 1 mm thickness. It proved to be a very good technique and allowed a wood repair of very narrow guage.

Tasks remaining in this area are

  • Rebore for new bridge pins
  • Notch (chisel) treble bridge
  • Install new bridge pins
  • Scrape/sand soundboard
  • Fill remaining minor imperfections
  • Varnish soundboard and bridges

Stieff Plate Removal and Veneer repairs

Disassembly Complete
Yesterday, disassembly came to an end, as I was down to the soundboard! Ryan helped me remove the plate. We used the shop crane to good advantage. I’m glad we had it! Lesson learned: bind points are at the front of the piano, not at the back. Thus, it is important to lift primarily at the front. It wasn’t a problem as we went slowly and monitored progress well.

Piano vintage confirmed:

While the eBay listing for this piano suggested it was made in 1905, the serial number is only three different from my own piano, which had been dated to 1911 by the prior owner. Upon the removal of the plate we found the 100 year old chalk marks on the back which clearly identify this piano as 1911. End of story.

Veneer Repair Begins
My hypothesis is that the piano was stored on its side in a damp location at one time. There is evidence of mold on the soundboard and bridges of the piano. The veneer suffered buckling and separation on the left side. Repair to the buckled veneer is to be as follows:

  1. Rout 1/8″ channel through the buckled veneer at its peak to relieve the buckle.
  2. Re-glue the veneer
  3. Fill the routed channel

The inside veneer was separated at the top. It was re-glued using Titebond glue applied with a veterinary syringe.

Stieff Evaluation and Disassembly

This week, I took a closer look at the piano, while disassembling it. Generally, I found that nothing was worse than I knew it could be, but a few things were not as good as I had hoped:

  • In preparation for measuring downbearing, I attempted to bring the piano up to pitch. I found at least a dozen unisons which would not hold pitch.
  • Almost uniformly, I measured zero downbearing from bottom to top.
  • The source of the veneer damage is certain to be water damage. I think that at one time the piano was stored on its side in damp or wet(!) conditions. There are mold markings on the left side of the sound board and on the bass bridge.
  • The hammers do not look as good as I thought they might be prior to removing the action. I guess that’s to be expected, as you can see them better once the action is removed! In any event, they appear to have been reshaped at some point. The topmost hammer is odd. Hammers in the top octave have worn through to the wood core. It is not clear whether the hammers are original or not.

BUT … I wanted to rebuild a piano, and this is a great one to rebuild.

There are also some really good things about the piano that I appreciate now that I have begun to dismantle.

  • The keybed is flat and looks great!
  • I found a missing ivory keytop inside the case. That should make a complete set. I’m pleased to have an ivory keyboard
  • I should have known (could have looked at my Stieff in the living room), but I am pleased to see agraffes from the bass through the first two thirds of the treble. Theory states that’s good for tuning stability, and that makes sense.
  • The action is really in great condition. It has kept good regulation and aside from hammers shows no serious wear or damage.


More pictures on Flickr.com

Grand Piano for Syracuse Arts Academy

After buying the Stieff grand for myself in October of 2005, I’ve wanted to get back into piano rebuilding … particularly grand rebuilding. I thought it would be good to pick up an inexpensive grand as a first experience with grand rebuilding. I’ve also thought that the foyer of Syracuse Arts Academy (Terri’s new school) should have a grand piano. A grand piano is just a suitable icon for an “arts academy”, and of course it would add to the music program in a “grand way”.

These two objectives came to an obvious conjuncture, when I saw an affordable Stieff piano on eBay. I bought the piano and went to southern California to pick it up on June 9. I hope to have it rebuilt and in the school by October.

The completed eBay auction is here: (Ebay Auction)

I’ll be documenting progress on the project here. Terri took nice pictures of the California move. The pictures are here (Flickr.com).