Trimming Key Leads

A problem that I occasionally find in older pianos is that of expanded key-leads.

These expanded key leads are causing the keys to bind against each other. This issue was caused by rodents living in the piano, as is evident by the teeth marks on the keys.

If you look at a piano action, you will notice that the hammers at the bass end are much larger (and therefore heavier) than the hammers at the treble end. The heavier bass hammers take more force to push toward the strings than the lighter treble hammers.

In order to create a consistent amount of pressure needed to play the keys across the keyboard, lead weights are pressed into the sides of the keys. Keys that push heavier hammers have more weight pressed into them than keys that push lighter hammers. The lightest hammers at the far right end of the keyboard have no weight added at all.

If moisture or an acidic environment is introduced into the keyboard, it will cause the lead to oxidize and expand. Some technicians claim that keys that are made from basswood naturally create a slightly acidic environment. This means that the best way to avoid this with a basswood keyboard is to aerate the keys by leaving the fallboard open at all times. Other ways that key leads can oxidize is if water is spilled into the keyboard, if the piano lives in a very humid environment, or if rodents live in the piano and are urinating on the keys. Usually, you can get an idea about what the cause is by looking to see where the oxidized leads are located. If the whole keyboard has expanded leads throughout, it is likely the cause of high humidity or unventilated basswood keys. If the oxidation is concentrated in small areas, there was likely a liquid spilled on the keyboard or mice living in the piano.

A little bit of oxidation of the key leads wont hurt anything, but eventually the leads can expand so much that they will rub on neighboring keys. This will cause friction and result in sluggish or binding keys. When this happens, they key leads need to be trimmed so that they are once again flush with the side of the key. Be careful when undertaking this process, as lead dust is toxic if inhaled. Wear a respirator and gloves, and have a vacuum with a HEPA filter handy to clean up the dust during the process.

The first step is to remove all of the offending keys from the keybed.

An expanded key-lead.

Set them down on a rag and vacuum up any lead dust that is left on the keybed. Using a sharp chisel, slice through the expanded key-lead so that it is flush with the side of the key.

Make sure your chisel is sharp before cutting into the key-lead.

Pushing the chisel through the key-lead.

The goal is to create as little dust as possible, so avoid using a file or sandpaper. Go down the line of keys, slicing through the expanded leads on each side, and vacuuming up the dust and lead scraps.

The trimmed key-lead.

After trimming the leads, I like to brush some lacquer or shellac over the exposed sides of the leads to prevent further oxidation.

Both sides of the key-lead have been trimmed flush with the key.

Replace the keys and test them to make sure they all move smoothly. Finally, vacuum up any lead dust that fell onto the rag.

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Re-Tubing a Tracker Bar

The upper stack of a player piano after replacing the lead tubing with new rubber tubing.

One of the more delicate parts of a player piano system is the series of small tubes connecting the tracker bar to the valves. The tracker bar is the brass bar in the top-center that “reads” the holes in the music rolls.

The tracker bar

When the pedals of a player piano are pumped, a vacuum is created inside the body of the system (aka the “valve chest”). This is where the valves are located. The vacuum also continues up through all of the tubes and into the tracker bar. When a hole in the music roll passes over the tracker bar, air is pulled into the corresponding tube which directs it to the “pouch board”. The pouch then operates the corresponding valve (which plays a specific note on the piano). In most old player pianos, these tubes are made of lead. Yes, that heavy, toxic metal that you hear so many bad things about. While lead is not harmful as long as it isn't disturbed, it can oxidize over time. This causes problems in player pianos because as the inside of the lead tubing oxidizes, it creates small, dusty particles that get pulled into the valve chest and can interfere with the action of the valves. This lead oxide can also be harmful if it is inhaled. Be sure to wear a lead-approved respirator as well as gloves while handling lead tubing. It is impossible to tell from the outside if the lead is oxidizing or not, because the outside of the lead tubing will be coated with shellac in most pianos, preventing its oxidation. The only way to tell if there is a problem is to cut open one of the tubes and look inside. If there is no powdery substance inside, simply splice the tube back together with a small piece of rubber tubing. If there is oxidation inside, the tubing should all be replaced.

For more information about the danger of lead tubing, take a look here: http://www.player-care.com/lead_tubing.html.

Before starting, order your new rubber tubing. You can get it here: http://www.player-care.com/tubing.html. Standard tracker bar tubing is 9/64” Inside Diameter. You will need at least 100 feet to re-tube an entire tracker bar. While you are at it, order 100 straight brass connectors for 9/64” ID tubing as well. You will need these later.

You will need to remove the upper stack (this is the assembly that sits on top of the keyboard and is comprised of the valve chest, striker pneumatics, and spoolbox). On Standard-type player actions, this is held in place by one large vertical screw on the right side and four medium-sized horizontal screws on the left. After removing these, the player action can be slid toward the front of the piano and lifted out. Rotate it 180 degrees and set it on a sturdy workbench. Before cutting anything, make note of any tubing that connects to any other devices. There will usually be a few tubes connecting to the tracker pneumatic on the left side (if viewed from the front). Make a drawing of where these tubes connect on each end, as they need to be re-tubed in the same order.

The tracking pneumatic. Before cutting the lead tubing, be sure to make a diagram of all tubes and where they connect on each end.

Using a shears, cut through the center of all of the lead tubing. The tubing is probably cemented directly into the pouch board. You will need to remove the tubing from the board. This is usually easy to do after the cement around the tube has been chipped away. Just gently grab the tube with a pliers and twist it back and forth until it comes free. If the tube breaks off, turn a screw into the center of the tube and use that to pull out the stump. To remove the tubing from the tracker bar, separate the tracker bar from the spoolbox by removing the two machine screws from each side. Soak the tracker bar in kerosene for a day or two until the tubing has softened enough to be scraped off. Give the tracker bar a good polishing with 0000 steel wool while you have it out.

The removed tracker bar ready for cleaning.

The backside of the spoolbox after removing the tracker bar. Notice the holes in the pouch board at the bottom of the photo where the lead tubing has been removed from.

While the tracker bar is soaking, the holes in the pouch board need to be modified. The new tubing cant be cemented directly into the board like the old tubing. Instead, the straight brass connectors that you bought are going to be glued into the board with burnt shellac. Burnt shellac can be made by buying a can of clear shellac from any hardware store, pouring about a cup into an old steel pot and igniting it. The alcohol will slowly burn off and the shellac will become thicker. Put out the flame by putting a lid on the pot after about 5 minutes. Let the shellac cool and then test the consistency. It should be about as thick as Elmer's Glue. If it is not thick enough, burn off some more alcohol. If it is too thick, add a bit of denatured alcohol. Burnt shellac will create an airtight seal, will stick to just about anything, and can be easily removed with alcohol. It also takes a very long time to set (sometimes up to a week).

New brass connectors.

The pouch board removed from the upper stack.

The brass connecters are slightly smaller diameter than the lead tubing that was glued into the pouch board, so the holes need to be plugged and re-drilled with the correct size drill bit. To plug the holes, first separate the pouch board from the upper stack by removing all of the screws going through the face of it, then clean any remaining bits of glue or tubing from the holes where the tubing was inserted. Keep track of which screw was where by finger tightening each screw into its correct hole in the upper stack after the board has been removed. Next, cut 88 1-inch-long pieces of wood dowel that will fit snugly into the holes. The proper size for me was 3/16”. Normally when plugging holes, I use plugs that have the grain running horizontally across the plug so that screws wont slice through them. In this case, we are just gluing brass tubes into the holes, so the orientation of the grain doesn't matter, and we can use dowels which have the grain running the length of the dowel. Use any wood glue to glue the dowel pieces into each of the pouch board holes. Push the dowel in about halfway. Once the glue for all of the dowels has set, use a fine toothed saw to cut them flush with the top of the board.

Wood dowels.

Dowel glued into the pouch board.

Dowel cut off.

Waiting for glue to dry.

Flush cutting the dowels.

Pouch board after plugging holes.

Use a 5/32” brad point drill bit to drill a hole through the center of each dowel. Drill as vertically as possible. Dump out any wood scraps in the hole, and gently blow each one out with compressed air. Using a small brush, paint a bit of burnt shellac onto the side of a brass connector. Twist the connector while pushing it into the board so that the shellac makes a collar around the connector. Push the connector about halfway into the board. Repeat this with the rest of the holes. At this point you can set this board aside for at least a few days while the shellac hardens.

Plug after drilling and inserting a brass connector.

Applying a drop of burnt shellac to the side of the brass connector.

Spin the connector into the pouch board to create a collar of burnt shellac.

Set the board aside for a week to allow the shellac to dry.

When the shellac is hard, re-attach the pouch board to the player action. The next step is to rough cut all of the rubber tubing to go from the tracker bar to the pouch board. Remove the tracker bar from the spoolbox by loosening the four machine screws from either side. The length of tubing can be estimated by holding one end in the approximate location inside the spoolbox and loosely running the other end to the correct brass connector. Be sure to leave some extra slack just in case. Cut the tubing, dip one end in a lubricant, and slide it onto the proper brass nipple on the back of the tracker bar. Make your way through all of the tracker bar nipples, making sure not to loose track of which connector you are measuring to. Cut the four pieces of tubing for the tracking pneumatic as well, following the drawing you made earlier. Attach these to the tracker bar.

Estimating the length of a piece of tubing.

Lubricating one end of the tubing.

Pushing the tubing onto the tracker bar nipple.

Using a razor blade to keep track of which brass connector I am measuring to.

The tracker bar halfway tubed.

Tracker bar fully tubed (except for the two on the left which will lead to the tracking pneumatic).

The tracker bar can now be reattached to the spoolbox. You may need to remove the thin panel in the back of the spoolbox to be able to insert the tracker bar from the back. Reinstall the panel after the tracker bar is reattached. Start sliding the free ends of the tubing over the brass connectors. Take your time and make sure that each tube is connected in the correct place. Use a flashlight and look at the back side of the tracker bar to be sure you have the next tube in line. If you have too much slack in a tube, cut it down a bit so that all of the tubes look clean and organized.

Pouch board re-attached.

Spoolbox back-board removed for easier installation of tracker bar.

Tracker bar tubing coming out of the back of the spoolbox.

Spoolbox back-board reattached.

Attaching the tracker bar tubing to the brass connectors. Make sure the correct tube is being connected.

Keeping the tracker bar tidy after it has been attached to the brass connectors.

After all of the tubing has been attached to its brass connector, reinstall the player action and give it a test.

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Improving Tone By Reshaping Hammers

Hammers with grooves in the felt on the left. Freshly sanded hammers on the right.

Over time, the pounding of a piano's hammers against the strings will dig deeper and deeper grooves into the hammer felt. As the felt gets compacted and the area of the hammer that strikes the strings get flatter, larger, and harder, the felt provides less cushion during impact. This causes the tone of the piano will become sharper, more harsh, and more percussive. In addition, harder hammers are more likely to break strings. To restore the tone and correct felt density, the hammers need to be sanded until the grooves disappear.

Before beginning the sanding process, remove the action from the piano and gently lay it on a sturdy workbench.

Marking a guideline for the hammer's strike point.

The marked guideline.

The hammers must be carefully sanded so that they retain their original shape. The point of the hammer that strikes the string (a.k.a. the “strike point”) needs to be at the very tip of the hammer. To make identifying the strike point easier, use a straightedge and a pencil to mark a line along the center of the wooden hammer core and out to the edge of the felt. This guideline will let you easily see the optimal strike point during your sanding.

A hammer sanding block.

Make a sanding block by gluing a strip of coarse sandpaper to an inch wide piece of wood. Gently but firmly hold the hammer in one hand and use the sanding block to shave felt off of the underside of the hammer. Take your time with this. While sanding, follow the curve of the hammer by moving the sanding block in an arc over it. Always sand toward the strike point of the hammer.

Sanding the underside of the hammer.

The lopsided hammer after sanding its underside.

Once the grooves on the underside of the strike point have been sanded down, repeat the same process on the top side of the hammer. Keep sanding until the hammer is round again and the tip of the hammer is located on the guideline. While you are doing this, take the bit of extra time to make sure the hammer is round and looks good. Don't leave any flat spots.

Sanding the top side of the hammer.

Work your way through each of the hammers. Once you get to the high treble, the felt will be so thin that you shouldn't touch it with sandpaper. Just leave that section alone. Sanding wont change its tone much anyway.

The finished, well-rounded shape.

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Common Bridge Issues

Over time, the tension on the strings causes the holes in the bridge to become enlarged. Note the pin in the center of the photo with the hole on its left side.

Does your piano have a section of keys that just sound terrible? Do the strings make clunking or rattling noises? Do single strings have a warbling sound to them? These are common symptoms of issues with the piano's bridges. There are two bridges in a piano: the short (bass) bridge and the long (treble) bridge.

Bridges in a piano have two jobs to do. The first is to provide a termination point for the speaking length of each string (this refers to the section of each string that is struck by the hammer, vibrates, and produces the desired sound. There are several non-speaking sections of each string that are usually muted with strips of felt). The termination point is achieved by the use of iron “bridge pins.” These pins are sturdily embedded in the wood of the bridge and provide the lower end point of vibration for the strings. The second purpose of the bridges is to transmit the vibrations of the strings to the soundboard where they can be amplified to produce the volume that we expect from a piano.

The most common issue with the bridge is that of loose bridge pins. Over time, the sideways force exerted by the string causes wood surrounding the bridge pin to be crushed. This causes a loose fit of the pin in the bridge and can cause the noisy issues described above. There are other ways that a bridge can fail that will also cause these issues, but I won't get into those here.

The way to fix this problem is to remove the offending strings from the bridge, pull out the loose bridge pins, fill the enlarged holes with epoxy, drill new bridge pin holes, insert the bridge pins, and reinstall the strings.

The strings that pass the offending bridge pins must be loosened slightly.

After identifying the bridge pins you want to work on, follow the strings up to the tuning pins. Before working on the bridge, you need to loosen each of the tuning pins that correspond to the strings over the target bridge area. If you are working in the tenor section, take a closer look at the three strings. One of them will loop around a hitch pin at the bottom and double as a string for an adjacent note. The tuning pin for this string must be loosened as well. Turn the tuning pins in small amounts while lightly pulling the strings towards you. This will keep the coils tight around the tuning pins while they unwind. Keep loosening the tuning pins until the strings have enough slack to pull them away from the hitch pins and the bridge.

If there are enlarged holes in the long bridge in the area underneath the bass strings, you will have to remove several of the bass strings to gain access to that part of the bridge.

Holding tension on the strings while turning the tuning pins. I wear gloves to prevent any moisture on my hands from causing the strings to rust.

The loosened strings after being pulled away from the bridge.

Using a lineman's pliers, note the angle of the pins, and pull them straight out along that angle. 

Pulling out the bridge pins.

A removed bridge pin.

Use a piece of cardboard or styrofoam to keep the bridge pins in the correct order.

Keeping the bridge pins in order. Note how the right-most string of the note next to the one being worked on has also been removed.

Once all of the offending bridge pins have been removed, cut and mix a small amount of PC wood epoxy putty and fill the enlarged bridge pin holes. After the epoxy has hardened, sand it flush with the bridge.

The bridge after filling with epoxy and sanding.

Measure the diameter of your bridge pins with a micrometer and acquire a drill bit of the exact same diameter or of the closest wire gauge size on the smaller side (an overly tight bridge pin is better than a loose one). Drill new bridge pin holes while trying to duplicate the angle of the surrounding bridge pins as closely as possible. Push and twist the bridge pins back into place, reinstall the strings, and pull them back up to pitch.  Any buzzing, warbling, or clunking will hopefully be eliminated.  If not, you may have more serious bridge problems.

The bridge with one pin re-installed and a second hole drilled.

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Replacing Loose Tuning Pins

Every once in a while, I go out on a tuning job only to find that the piano in its current state is impossible to tune. Some tuners throw this sentiment around whenever they encounter a piano that is worth anything less than a few thousand dollars. “Impossible to tune” to these kind of tuners just means that the piano is incapable of sounding like a nine-foot concert grand. That's not what I'm talking about. These pianos of “lesser value” are in many cases much more important than the ones in the concert halls and auditoriums. These pianos are seen and heard every day. They bring warmth to homes and joy to the people in them. So, when I say “impossible to tune”, I mean it literally. The piano is physically incapable of making music. The most common reason for this is because the tuning pins have lost their grip.

Bass tuning pins in a Kimball upright. The shiny pins on the left are slightly larger replacement pins. The dull pins on the right are the originals that no longer are able to do their job of holding tension on the strings.

In my post “Loose Tuning Pins CA Glue Repair” I described a procedure that is used to tighten-up  tuning pins that are slightly loose. Sometimes the pins have gotten so bad that CA glue won't do enough to make the piano functional again. In these cases, it is necessary to replace the tuning pins with slightly larger ones.

The way that a piano holds tension on its strings is by having one end of each string looped around a stationary iron “hitch pin” and the other end wound around a tuning pin. These pins are between 2 and 2-1/2 inches long, however only about an inch of them is visible. This is the part that the string is wound around, as well as the part that a tuning wrench is placed over in order to turn the pin (changing the tension on the string and consequently changing the pitch of the string). The other inch and a half of the pin is tightly embedded in a laminated block of wood called the "pinblock". The pinblock is made of several sheets of wood that are glued together so that the grain of each layer runs in a different direction than the layer next to it. This layering adds a lot of strength and resilience to the wood. This is vital when each of the 200+ pins has about 150 pounds of tension on it.

The tuning pin and coil after loosening 3/4ths of a turn.

Over time, the wood fibers in the pinblock get slightly crushed and start to loose grip on the tuning pins. When this happens, the pin requires significantly less force to turn, and in bad cases the tension of a string at the proper pitch is enough to turn the pin all on its own. This is what I am talking about when I say “impossible to tune”. The string can be pulled up to pitch, but as soon as the tuning wrench is released, the tuning pin slips in the pinblock and the string goes out of tune.  In these cases, the best solution is to remove the tuning pins and replace them new, slightly larger pins.

If you plan in replace a large number of tuning pins, you want to be sure that the larger pins are actually going to help your problem. If the pinblock of your piano is severely cracked or has delaminated, it needs to be replaced before any other work is done. If you are unsure as to the condition of the pinblock, it may be worth it to just replace a pin or two here and there across the length of the piano, pull the strings up to pitch, and wait for a few weeks while occasionally giving a firm strike on each of the corresponding keys. If the strings with the replaced pins haven't drifted far out of pitch at the end of this test period, you can go ahead and replace the rest of the pins.

Before you start, you will need a tuning wrench, new tuning pins, a tuning pin setter or punch, a hammer, a thin flathead screwdriver, and a few different sets of pliers. 

Tuning pins come in sizes ranging from .276” to .306” in diameter and in .005” increments. To determine the size you need, remove one of the loose tuning pins by turning it counter-clockwise until the string is loose enough to remove from the pin (about 3/4ths of a turn). The string has a tight bend at the end (called a becket) that is inserted into a hole in the center of the pin. Pry the becket from the hole with a flathead screwdriver. 

Prying out the becket.

Releasing some tension by pulling the string off of the termination pin.

In the bass of many upright pianos, you can release a bit more tension by pulling the string over the termination pin just below the tuning pins. The coil can now be pulled all the way off the tuning pin. Using a tuning wrench or a string crank, turn the pin counterclockwise until it comes free from the pinblock.  Using a micrometer, measure the diameter of the pin. Find your size here: http://www.vandaking.com/s-210-piano-tuning-pins.html. If your old tuning pins loosened instantly under proper string tension, order new tuning pins that are two sizes larger. If the old pins loosened slowly over time under proper string tension, order one size larger. Make sure you get new pins that are the same length as the originals.

The coil fully removed from the tuning pin.

Spinning the pin out with a stringing crank.

The tuning pin has been removed.

At this point, there is a bit of disagreement between piano technicians as to the proper technique. Some technicians will drill or ream out the tuning pin hole to a size just slightly smaller than the diameter of the new pin. Others will clean out the hole with compressed air, a vacuum, or a long slender brush. Some technicians don't prep the tuning pin hole at all. In this case, the pins were already so loose that the holes did not need to be re-sized, and so I went right ahead and hammered the new pins in.

The tuning pin setter and the new tuning pin ready to be hammered into the pinblock.

In order to install the new pins, use a tuning pin setter and a hammer to tap the new pins straight into the pinblock. Only tap the pin in until it sticks out just slightly further than the original pins around it. The goal is for the bottom of the string coil to end up 3/16ths of an inch away from the plate (or the pinblock if the plate doesn't cover the full height of the piano). Pull the coil onto the new tuning pin and insert the becket into the tuning pin hole. If you pulled the string off of the termination pin earlier, place it back along its original path. Make sure that the string is still following its path through the bridge pins down below the keyboard. From this point, you will follow the same directions in my “Replacing a Broken String” tutorial.

The new pin after hammering.

Placing the coil on the new pin.

To see more photos of this procedure, take a look at Chuck Behm's instructions in this helpful PDF.

Checking to make sure the strings are all still following the correct path over the bridge.

The pin after bringing up to pitch.

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