One thorny problem has been the bass bridge, which has nothing to do with player action, it's part of the Kingston piano. The bass bridge, for those of you who don't know, is a curved bar of wood about 2 1/2 inches high and about 1 inch thick and about 1 foot long. The strings for the lowest notes on the piano are stretched across it in a slight arch, pressing the bar into the piano's sound board which amplifies the sound of the vibrating string. If the bass bridge is poorly installed, damaged, or poorly constructed, then sound from the whole lower range of the piano will be poor.
Where the strings stretch across the bar, they are also threaded between two pins, forming sort of a elongated "Z". The 2 pins are each angled toward the string, and fitted very snugly in holes in the bridge. Over time, because of humidity, dryness, age, sideways pressure of the strings, etc. the pins can loosen and even split the wood, again resulting in poor bass tone.
About 40 pins on mine were seated in split holes.
What to do?
Well, my dad was a carpenter of sorts, and a few years ago he took the original bass bar and duplicated it using a piece of oak and some of his woodworking tools. The result was fairly good but not perfect. There are three important dimensions: the bridge must make perfect flat contact with the sound board, the strings must zig zag between the pins; and the strings must make contact with the wood of the bridge at precisely the same point as they make contact with the pin, which means the bridge is beveled crisply across the pin holes. Getting those three dimensions right was a challenge: some of the strings didn't zig zag enough because of imperfect hole positioning, some of them were touching the wood/pin inconsistently, and I don't think the contact with the sound board was perfect. But I had his improvised bridge installed for quite a few years, and we have had lots of fun from from the piano.
A few weeks ago I started researching the issue, and found these options: (1) have the bass bar duplicated by hand (fairly expensive) (2) have it replaced with a generic blank (not as expensive but not as good and (3) repair it with slow-setting epoxy. I talked with a fellow online about having it duplicated and he didn't want to mess with it. So I decided to give epoxy a try. Step by step, here's what I did:
- I bought some slow hardening epoxy from Ace
- I mixed up an ounce at a time
- I used a wire to poke the epoxy down the hole where the wood around the pin was cracked or deteriorated
- I rubbed some vaseline on the pin and poked it firmly down into the hole
- The cracks were at the top, on the surface of the bridge, so when the pin poked down, it settled into place with the right position and at the right angle
- I made sure the epoxy was mounded up around the pin above the surface of the wood in order to have solid reconstruction of the area around each pin's hole
- I worked my way all the way down both sides of the bass bridge
- There were about 10 holes that were solid and didn’t need any epoxy, the rest I epoxied
- After the epoxy had set but not hardened, I used vise grips on each pin, gave it a little twist and pulled it out
- The next day after fully hardening, I used my orbital sander to flatten the mounded epoxy
- Then I used a small sander attachment on my Dremel (about 3/4 inch diameter) to sand the proper bevel across each hole or pair of holes
- I had a couple of holes I had to re-epoxy
- Finally after curing a day or two I installed it in the piano, inserted the pins (used a clamp to move each string sideways enough so I could insert the pin straight in its hole) and tuned it up
- Result: sounds really good across 3/4 of the bridge, from the low end up
- The upper end of the bridge I don’t think is seated firmly on the sounding board, the strings don’t resonate as well (there were three dowels for the bridge to set on and keep it in place, and the upper pin is broken so the bridge seems to be a bit off location at the upper end)
- I did not glue the bridge down (yet)
- So far there's been no sign of failure
