Posts tagged hammer
Recently i’ve had the opportunity to work on a church piano – an older Chickering. But i must say, this piano was an interesting one to tame. I use the word tame because it was out of control. The touch was not only uneven but INCREDIBLY difficult to play. Most fine pianos have a touch weight of about 50-55ish grams of weight at the key. This one was a whopping 80+ !!! First things first… chase down the friction. That blog will be for another day though. After friction was in the ballpark, i was still faced with a piano that had a touch of 65ish grams. Time to consider putting this piano on a diet. Yep. You heard me. This piano was overweight and i was about to transform the touch.
So where does weight come from? Many months ago i wrote a blog on piano weights. It can simply (and yet so difficult at the same time) be measured in 2 forms – static weight where we are doing a dead lift – the hammer has yet to move. The other is created by rotational inertia. The hammer has started to move… how much effort is required to continue to move the mass of the hammer. The former mainly deals with soft playing… we’re not concerned about velocity but simply getting the hammer in motion. The latter however deals with everything above soft playing and truly is the more important factor. Static weight can be counterbalanced in the key like a see-saw. Rotational inertia however can really only be changed through the mass of the hammer itself. Because static weight again really only affects soft playing, when i sat and just played the piano (after friction was removed), it still felt heavy and burdensome. So it was time to trim the fat – reduce what i could on the hammer without compromising either structural integrity or tone. How does one leave the strike point of a hammer the same and yet reduce dead weight? Take a look at the pics. The one on the left is the original. Square and bulky. The one on the right – the more parabolic shaped one is one i adjusted. The tapered ‘shoulders’ of the hammer offer insignificant contribution to tone… if any. And so i spent the next 3 hours shaping hammers. Take a look at the two ‘tails’ – the end parts of the hammer. On the left – one that is tapered while the right, original. The net result? Reduction in about 1.3-1.5 grams of fat. One point three??? Perspective here… a nickel weighs 5 grams. You ask “How does anyone get excited about 1.3 grams of weight?” Ahhh therein lies the magic. Every piano has an ‘action ratio’ meaning one gram at the hammer accounts for usually around 5 grams at the keyboard. OK so do the math… this piano has a 5.5 action ration. 1.3 gram reduction x 5.5 action = 7.1 gram reduction of touch weight – the exact amount i needed to make this piano feel dynamic and alive. I’m so happy! 😀
Alright listen up… literally. Listen for clicks when you play each note on your piano. The cause? Well… kinda like the last post of Cause & Effect, there are many many things in a piano that could make noise but the most common – 2 things: Loose flange screws and loose flange pins.
Ok calm down… i know you don’t know what a flange is so i’ve conveniently uploaded a pic for you. Shown here are the hammer, shank and flange. The flange is the jointed piece at the bottom that is attached to the hammer rail. When the hammer strikes the string, believe it or not, the force will go running down the shank and into the flange. If the flange screw is loose, you’ll hear a click. After you tighten the flange screw, if it still makes noise, dollars to donuts it’s the flange pin itself. The flange pin is a small little steel pin. When it gets worn out and the joint is too loose, it’ll manifest that looseness by clicking. There you have it! The most common source of ‘clicks’ in pianos. And like the other post on Cause & Effect… better to ask the technician to remedy the situation.
This post speaks to the problem of sticking piano keys. There are usually about 6 spots to check on any piano if a note is not returning to normal playing position. But before we get into the mechanical, think of the obvious… is it getting blocked? I mean… believe me when i say i’ve seen LOTS of things inside pianos. Here’s my list thus far: pencils & pens, toys, hair pins and bands, sheet music, tools, rubber bands, paper clips, coins of various sizes, ladies press on nails (ewww… that kinda creeped me out finding that one… especially since i got the piano from a home where she had died), believe it or not metronomes and decorative piano blankets. Hmmm have i missed anything? So make sure it’s not getting blocked.
Once you’ve determined that it’s not blocked or broken, however, there’s a REAAAALLY good chance friction is to blame. Usually the hammer FLANGE is the culprit – it’s the joint connected to the hammer. About 80% of the time there’s wayyy too much friction on that joint and the centre pins need replacing. Two other joints – the action flange (flange is just another word for joint BTW) and the whippen (repetition lever) also have jointed parts. Any time you introduce a joint, you also have potential for problems. So that makes up 3 of the problem areas. Then the key stick has two bushings – each of which could also have too much friction. And finally, the key slip – the rail in front of the key sometimes catches on the front of the key. Invariably it’s one of the 6 parts. How do you go about fixing it? Hahaaaa… i didn’t mention i would give the solution… only the cause of the problem. MOST problems can’t be fixed without a technician. Sure you can look down inside and see if there’s something obvious but if it’s not… you need to get an expert in to address the problem.
Recently i was hired to work on a Broadwood grand. Now for those of you who don’t know, Broadwood has an illustrious place in the world of piano making. Established (get this) in 1728 (yes you read correctly), this company made pianos for royalty (obtaining the Royal Warrant for manufacturing – see lower left photo) and had probably the most famous historical endorser Beethoven himself. Upon gifting a grand piano from Broadwood, Beethoven wrote a thankyou letter back in February 1818: ” I shall regard it was an altar upon which I will place the choicest offerings of my mind to the Divine Apollo”. Think about the fact that this company was established 125 YEARS before Steinway. Now obviously in the early days they were manufacturing clavichords, harpsichords and square grand pianos. The Broadwood company became known for their actions (internal mechanisms) and also is credited with the sustain pedal.
The piano i had the opportunity to work on was a “barless” grand meaning that it had no reinforcement bars or ‘struts’ to hold the tension of the almost 18 tonnes of string tension. Instead, Broadwood made a full perimeter frame which appears to be almost double in thickness – making this an extremely heavy instrument. (see photo of strings) The major problem with the piano i worked on was that it had a cracked action rail. If you’ve ever seen the inside of a grand piano, you’ll know that all of the hammers are screwed in place to one long rail called the action rail. If the action rail is cracked, many things happen – first, you don’t have a solid base to attach the hammers. That creates ‘travel’ where the hammers will jostle about not hitting squarely the strings. Second, believe it or not, if a screw is so much as even loose on an action rail, you’ll hear the subsequent ‘click’ of the hammer. So there were a number of hammers clicking before i attended to it. And finally, the regulation. Regulation is the process of fine adjustments to streamline the flow from key to hammer. It’s what makes a piano feel ‘right’ or positive. With a cracked action rail, the hammers wouldn’t stay in alignment. After quoting on this job, it then struck me… “what have i got myself into?” Action rails have nearly 200 screw holes, thickness requirements down to the thousandths and fore and aft placements that need tending to. Well i’m always up for a challenge. And so before ripping this piano apart, i went back to the calculations. There’s a joint near the hammer called the flange. And for those who are interested, mathematically, you should be able to compute flange height. Simply, the string height inside the body of the piano minus the length of bore (LOB) – which is the centre of the shank to the tip of the hammer SHOULD equal the bird’s eye. The what? The bird’s eye is the nickname given to the joint of the flange. See? It looks like an eye… kinda… ok maybe not… but it’s a steel pin surrounded by cloth inserted into wood. So after calculating the bird’s eye, i managed to then thickness sand the new rail just under 3 thousandths of an inch (about the thickness of a piece of paper). So once everything was installed? The moment i had been waiting for… it WORKED! but it just needed a lot of adjustments refitting the old parts. It was a fun experience and more than that, exciting to bring a tired Broadwood (the silk purse) back to life.
You may have heard a piano technician talk about voicing saying “Well we can voice those hammers down for you if you’d like”. First of all, most don’t know what voicing entails. Second, manipulating the hammers ‘down’ (up or sideways for that matter) doesn’t exactly fit any kind of tonal response you would think of. But before we get carried away describing what is going on, let’s define voicing: Voicing is the manipulation of very hard pieces of felt called hammers which strike the strings on the piano. At that strike point (please refer to the blog called Bright and Brassy Sounding Pianos) the hammers can either create warm sound, brassy sound, nasal sound, thin sound, percussive sound – all from the strike point of the hammer. Voicing then changes or alters the support of that strike point to get the desired response out of the piano. Voicing ‘down’ means to make the piano mellow while voicing ‘up’ means to make the piano more strident.
So here’s the pseudo exhaustive (or exhausting… take yer pick) list of what goes on in the voicing world.
- Hammer hardener
- Hammer softener
- Steam voicing
- Methyl hydrate/water mix
So i’m not going to pass judgement on what i think is correct voicing and/or techniques, but i WILL describe what’s going on in each of those methods. Without further adieu, here’s the list on what technicians do to pianos.
1. Needling… needling is by far the most common process in voicing. Pictured to the right is a voicing tool that i own. You will see that it has a needle in the tip. When you poke holes in hammers, it releases some of the tension and almost… ‘fluffs’ up the hammer. In doing so, the hammer can support the crown – the very tip to bring out the optimal sound of the piano. Most often this is used in reducing ‘high’ points – where one note will stick out above it’s neighbours.
2. Filing… hammers over time with heavy use will eventually become grooved. These grooves quite often make undesirable tones. Filing the hammers reshapes the worn parts so that the grooves are minimized. Please see the picture on the left for a hammer file voicing tool.
3&4 Hammer hardener and softener are both commercially available substances which drastically alter tone by use of chemicals.
5&6 Both steam voicing and methyl hydrate/water change the hammers by fluffing up the hammers much like a piece of paper when it gets wet. When paper gets wet and then dries, it is no longer flat but ‘crinkled’. In like manner, hammers ‘puff up’ with the addition of methyl hydrate and water mixed or steam voicing.
So there you have it – the entire list (that i know of) to alter piano tone.
Every piano has one… a black hole. It’s the place where all the pencils disappear to. Paperclips magically are sucked into it… Heaven forbid anyone should be doing their theory homework at the piano and an eraser falls inside. And once inside the abyss… gone forever! HAhaa… at least that’s what i used to think when articles would fall inside the piano when i was a kid. And on pain of death we were threatened to never go tinkering around the inside of the piano (which is still probably good advice for kids and pianos…lol). So when the piano tuner would come, he would unravel the mysteries of the universe… “Well… looks like that click sound is actually coming from a pen that fell inside. Oh and here’s another pencil.” I remember seeing the inside mechanism of a piano for the first time in my early teens. (Formally called the “action”). When i witnessed the hammers and levers i remember having this brainwave. “Sir? Can you make the keyboard on my piano heavier?” We had an old upright piano and with 4 kids – 3 of which ended up with diplomas in piano, you can imagine the beating it endured. But when i went to my teacher’s place where there was this beautiful modern 7′ Yamaha grand piano, i noticed how vastly different the touch was. And so the answer from the tuner? Simply “No”. No explanation. End of Story. I thought to myself, in all this gobbledeegook of levers maybe there was some adjustment that could be made to give me a grand touch. I was young and naive and this technician had no time to explain and so i was left with no alternative than to think that it’s impossible.
For the most part, however….unfortunately he was right. I’ve had MANY people ask me to transform their piano into a firmer touch but to understand piano touch more, i’d like you to think of your piano like a scale. On one side is the key of the piano – the black and white notes. On the other side remain the hammers and the action. So most pianos have about 55-60 grams of touch on each key. What that means is:
Finger Pressure (55grams) = Hammers + Friction
Most of the weight of a piano is in the physical motion of the hammer itself. Now if you know anything about hammers, put one on a scale and you’ll find out that it weighs about 8 grams. Attach it to a piano action and all of a sudden, there is a 5:1 ratio of hammer weight. What that means is that the lever system in the piano multiplies the hammer weight by 5. An 8 gram hammer then will feel like 40 grams at the keyboard. Add 15ish grams of friction and VOILA! Piano touch. A 9 gram hammer (times 5=45) plus 15 grams of friction forms a touch of 60 grams at the keyboard. ONE gram on the hammer makes a 5 gram difference at the keyboard. When you think that a nickel weighs 5 grams, adding one-fifth of that is not a whole lot of weight and yet you’ll EASILY feel the difference installed into a piano due to the ratio. Make sense? Is it not possible then to simply add friction to the piano? Adding friction is not the answer. Friction is a careful balance. Too little and the piano feels too ‘loose’ and results in noise. Too much friction and the piano has sticking parts and feels sluggish. If your piano is old however, you may have worn out “joints” or pivot points. There are 2 areas which can be monitored which make any piano feel more “positive”. One is key bushings (see the article entitled “Aye There’s the Rub) and the other is called the hammer flange. (A flange is just a fancy word for hinged part on a piano). The hammer flange… if you follow your eye down the stick (called the shank), you will see that it is jointed at the base. New flanges (albeit costly) and key bushings are the biggest culprits for too much/too little friction. And so without opening pandora’s box more… my original question to the tuner: Can’t you change simply change the touch on the piano? Operative word in that sentence is “simply”. It can be done. It’s just not simple.
Indeed, friction is one of the piano technician’s worst nightmares. At best, the piano is a simple machine – you depress a key, it lifts a hammer to strike a string. At worst, it’s a complex mechanism where levers and joints are in contact all the time and each surface area is potential for friction to either be too loose or too great: too loose and the piano feels ‘warbly’ and too tight and it either doesn’t function properly or feels like you have to work too hard to compensate for the touch.
I learned this only a few years back but the formula for touch on a piano is relatively simple (operative word being ‘relatively’). There is a 5:1 ratio of hammer weight to key. What that means is, for every gram of weight at the hammer there is 5 grams at the keyboard. An average hammer weighs in at about 8 grams (multiply by 5 = 40 grams). So if average touch on a piano is 55 grams per key, where are the other 15 grams of resistance coming from?? Answer: friction.
Today i had the opportunity to redo key bushings on a fabulous grand piano owned by one of the best jazz musicians in the area. With a lot of playing (both from his own practice and from his students), the bushings around the contact points on the keys were completely worn making almost a ‘knocking’ feel from side to side. A bushing is nothing more than a substance used to reduce friction between two contact points. In pianos, bushings are almost exclusively made out of cloth (some people mistakenly call it felt but truly it is cloth – woven together). The cloth then allows the interaction of joints. Centre pins are made out of steel and they need to interact with wood. Without bushings these two hard substances would click and knock together. As well, friction can be taken up by cloth in varying degrees of thickness. So the cloth is the perfect substance for acting as the ‘spacer’ inbetween.
Next time you’re at a piano, test the bushings. Take one key and swivel it from side to side and see if you sense a knock or a thunk. This will tell you they need replacement. Simply steam out the old ones (see pictures) and glue in new ones and you’re good for years to come.
So we looked at the most important pedal, sustain in Just Pedalling Part 1. In this post we’ll look at the remaining 2 pedals. The left pedal correctly named the “Una Corda” pedal is an Italian term with a translation that simply means ‘one string’. On every piano, 6 out of the 7 octaves of notes have more than one string. This means then that one hammer is either striking 3 strings simultaneously or 2 strings (depending on how low). The very bottom notes only have one string. If you depress the left pedal on a grand, watch the keys because the ENTIRE keyboard shifts about an 1/8 of an inch to the right. Physically what is happening is that the hammers are shifted out of alignment so that they are no longer hitting 3 strings but rather two (one string is left off – thus una corda). And so the piano becomes quieter because it is not hitting all 3 strings. But something else is happening. Piano hammers get grooves in them because they strike the same position all the time. When you depress the U.C. (una corda) (funny… my teacher used to simply write U.C. in my music… apparently we were supposed to know what that was about…lol) the piano also takes on a different sound due to the fact that the alignment of the grooves in the hammers are also out of sync. This strike of the hammer is now on ‘fresh’ ungrooved felt and makes the piano not only quieter, but mellower. (is mellower even a word?) So that is the CORRECT way U.C. is to work. On uprights, the keyboard cannot move and so it operates COMPLETELY different. Due to the fact that there is no side to side movement, how does one make the piano quieter? Simply by installing a governor – which is a ceiling or a cap on the volume. If you try and clap your hands but only allow your hand to go only 5″ apart, how loud can you clap? Not that loud because distance creates velocity and velocity, volume. In the case of piano hammers, uprights simply move the hammers closer to the strings to create the pseudo soft playing effect. Is it effective? Not really… for 2 reasons. One is that the touch gets drastically affected. When the hammers move forward, most pianos then have ‘gaps’ in the touch because it has travelled the hammers towards the strings. Problem 2 – there is no ‘fresh felt’ kind of sound like grands have. It doesn’t move the hammers out of the grooves.
Well… just when i thought i’d cover 2 pedals on one post, i’ve run out of both steam and time. Stay tuned for pedalling #3 on the sostenuto pedal… and the 4 variations! It’s a doozer!
I’m the first to admit, i’m not into physics – not to say i don’t enjoy it, but i’m untrained in the area of advanced physics. What i AM interested in though is the practical application of physics – more specifically the touch of the piano. A few years back i had a Yamaha C5 in my shop. Beautiful instrument. It was apparent however that the touch was simply ALL WRONG. It had been monkeyed with. So i applied usual regulation specs and it turned out nicely. However, there was one niggly thing sitting in the back of my head that just wouldn’t go away… and that is that the instrument felt somehow sluggish. At the same time i had been looking over some ideas on key weighting which is the concept of adding/removing lead weights into the keys to achieve a more balanced keyboard. For those who are unaware, key weighting is a common practice in MOST pianos. The key weighting is part of the balancing of the equation to achieve a certain initial weight at the outset of the key. (And if you don’t believe me, next time you’re near a grand, press down a key and look at the neighbouring keysticks – you may just catch a glimpse of a circular led weight inserted into the key. ) Anyhow, for kicks i thought that i would key weight this C5. Sure enough the touch improved dramatically. End of story? Nope… i was still bugged by that same sluggish feel. So i rechecked my work and i must say that at soft playing, the piano was EXCEPTIONAL. It wasn’t until you hit the fast notes that i noticed the problem. Well… the piano ended up selling but that problem lingered in the back of my head.
Fast forward 3 years. I have a client who is an engineer. We were speaking about physics, touch of the piano… and he just so happened to mention Kinetic Energy. I had a small epiphany… i thought to myself… IT DOESN’T REALLY MATTER HOW MUCH KEY WEIGHTING HAPPENS BECAUSE THAT ONLY REPRESENTS THE HAMMER AT REST POSITION. AHA! No wonder that piano felt great at soft volumes – there was little inertia and the key weighting was ‘closer’ to the ‘at rest’ weight. So… the ONLY way then to affect touch is to change the mass. Ok gears turning here… if i could measure the velocity of the hammer in travel (ie radar, infrared beam etc) and the weight of the hammer i can measure… then i would be able to calculate the Kinetic Energy. What that means then is that one could ‘reverse’ model the ‘feel’ of great pianos. The rotational radius is similar as pianos have become more standardized. The combination then of calculated KE and key weighting would make for an undeniable touch don’t you think? So if KE=1/2MV2… we know mass… if only i could determine velocity… hmmm… thinking thinking… could i borrow my cop friend’s radar gear? lol.