After having done it the hard way, it is such a delight to find the easy way by virtue of someone else’s good thinking! Such is the case with the wonderful jig described below. When applying new key tops to piano keys, the notches surrounding the black keys present a significant challenge. Except for the notches, the sides of the keys can be trimmed flush with a flush trimming router bit, in much the same manner as one would trim plastic laminate on a counter top. But obviously, a flush trimming bit cannot do the notches. When I did piano rebuilding in the 80’s, this issue was handled with a hand held file. It was very tedious work.
In the June 1991 issue of the Piano Technicians Journal an article by Bill Spurlock describes a router jig for cleaning the notches. The jig below is an implementation of his excellent thinking.
The jig is used once the sides of the key top have been trimmed flush using a flush trimming bit. When trimming, the notch is left untouched, and a perfect notch is acheived with this jig. The router bit is a 1/2" spiral bit. The stop is 3/16" steel. When I first fabricated the jig I had no steel in the shop and tried a stop made of 1/8" brass. The brass flexed resulting in inaccuracies. The 5/8" hole in the stop was drilled to accept a bench dog for clamping. When I replaced the 1/8" brass stop with the 3/16" steel, I found that clamping was no longer necessary.
Preparing an old set of piano keys for new key tops is a critical operation. I designed and built this router jig to perform the operation of keytop planing with accuracy and speed. To preserve the geometry of the piano action, 1 mm will be planed from the key to account for the difference in thickness between the old ivory key top and the new plastic key top. This also produces a good flat glue surface for the new key top and a nice square notch at the rear for a professional appearance. The old ivories needed to be replaced because of extensive cracking, chipping, and missing pieces.
The photo to the right shows the key after exiting the jig. Note that the clamping mechanism is a simple, quick lever which holds adequately and keeps the process moving. The loose plate between the key and lever is coated on the lever side with some beads of hot glue, to provide gripping surface that would not be present in the hard maple. The router bit is a 1-1/2 diameter flat cutting bit. Since the key is less than 1 inch across, this diameter provides a cutting surface for both left side and right side of the key. Order of operation is:
1) With jig against right shoulder insert into about 1/4 inch. move to the left to plane the front edge of of the key (and the existing key front).
2) Slide the sled in to plane the left side of the key.
3) Move the sled to the right, forming the nice edge at the back of the key.
4) Pull the sled out to plane the right side of the key.
This order of operation will provide for proper rotation orientation of the cutterhead and produce a splinter free surface.
The objectives of accuracy and speed are met. This set of 52 keys was planed in 45 minutes.
Hibernation? Death? Disaster? None of the above. Distraction.
Oh yes, I’ve been distracted. Following an interesting conversation with Terri, my wife, in October, we decided to shop for a suburban home that had a large shop to accomodate my woodworking and piano rebuilding activities. Working out of a storage unit was showing itself to be unfriendly to us both.
So we bought a house with room to build a shop and we’ve been busy with moving and updating the place at Pleasant View. It’s been hard to leave our beautiful condo on the golf course, but we are both enjoying being close to work. In the summer I expect to be enjoying a new shop!
The soundboard repairs are complete, and the board is just about ready for a finish coat of varnish. Today I started the notching work on the treble bridge. It was good work. I like it! I learned a thing or two. For some technical discussion, please see the discussion of this job at Piano World.
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
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
To begin work on the piano, I built shop legs. These temporary replacement legs will allow me to move the piano around in the shop easily, without placing stress on the legs. 8 inch casters are much different than 2 inch brass wheels!
More pictures are here. (Flickr.com)
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).