Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Stiff action----heavy piano action

Can someone tell me the possible contribution of let off, drop, and jack regulation in causing a stiff, heavy weighted action?

I hire a technician and he kind of regulate the hammer blow distance and it has no help in the stiff action I have. The action now feel like it required many force to push it down and make the hammer blow, so I am wondering maybe drop or jack regulation is not right??

My approach would be first to check for excess friction at Hammer, whippen and repetition lever flanges as well as the keys at front and balance rails- before looking at regulation issues.

Examine the pivot points, flanges, center pins. Look at this video to see more about hammer flange center pins.

https://www.youtube.com/watch?v=YTzS90lN8iE

Thank you for your response! What does it mean by the friction on the whippen and repetition lever? I mean how to I lubricate them?

You could either use a syringe with Protek CLP to get into those tight spots or remove the Whippens off the Action rail with a screwdriver and do them one by one; either way, you will have to remove the action. Also, lubricating usually only works as a band aid. The action centers, if it is the source of the friction problem, probably need to be reamed. If your piano is an older Steinway, 40+ y/o, look for a green residue on the center pins; this malaise, called Verdigris, occurs on many older Steinways, and if it is present, then the action centers need to be repinned. Early rising damper issues also manifest symptoms of a heavy action. The Dampers should start to rise off the string at about the half-way point of the Hammers journey between rest and strike. Hope this helps.

lube is a technique but may it may not get the results you want.
The flanges are bearing points and made up of a felt bushing and a brass center pin.
If The fit is too tight the better treatment is to size the felt to the pin with a water alcohol solution or even better, re-pin the flanges and size the felt using special tools made for the job.
Similar at the keys. Felt bushings too tight on key pins and the wood balance rail hole too tight.
All can be made to fit proper but it's a job for a tech.
Get a tech that knows how to evaluate your piano and can do what it takes to get it functioning like you dedire

regulating won't cure a heavy action. The first thing to figure out is the source of the heavyness. There are 3 main culprits:
1. Friction. You can assess friction by looking at the difference between how much weight it takes to get the key to go down and how much weight the key can lift. (the damper pedal must be depressed when assessing this). Modern pennies weigh 2.5 grams. Pre-1982 pennies are slightly more than 3 grams. Nickels are 5 grams. Normal down weight should be around 50-55 grams. upweight should be around 20 grams. Friction is downweight minus upweight divided by 2. If your downweight is 55 grams and your upweight is 20 your friction will be the difference divided by 2. 55-20=35/2 = 17.5 which is a little on the high side. Most friction issues come from tight hammer pinning or tight keybushings.

2. high action ratio. The amount a certain amount of key movement moves the hammer varies from piano to piano. If a mm of key travel moves the hammer 6 mm you will have a heavier action than if a mm of key travel moves the hammer 5 mm. Some remedies include: moving capstans or knuckle position.

3. Heavy hammers. The action ratio magnifies the weight of the hammers by a factor of between 5 and 6. So an extra 2 grams of weight on the hammer can feel like an extra 10-12 grams at the key depending on the action ration. That can be the difference between a normal feeling action and a heavy feeling action. Remedy: remove hammers and taper them to reduce weight.

A fourth possibility is that the hammers are too soft. This can create a heavy feeling because a larger effort is needed to achieve fortissimo.

Your problem could be a combination of 2 or more of these issues.

It's kind of weird because my measurement are uneven. I get reading a like downweight 65 and up weight 35 on the bass part and down weight 55 and up weight 35 for my tenor and soprano part...

What is your training in piano repair and adjustment? And what is your regular line of work, that is, do you work with your hands or your head or both? I am concerned that your working with the action of your piano may not have a beneficial effect.

I agree with Gene Nelson: your wisest course is to hire a competent technician, one who understands that regulating hammer blow distance does not loosen up a stiff action. Best wishes --

James, it seems you have started 4 threads on 2 different PianoWorld forums now. I posted the following in another thread here in the Technician forum:

The measurements you posted in the piano forum (55g down, 30g up) are normal and correct for most Kawai actions, so that is not the source of the heavy feel. The touch of the action can still feel heavy because of other factors

The touch of a GM-10K piano often feels heavier than the more expensive Kawai models because it has higher inertia: the hammers are made with heavier wood, and the action parts themselves are heavier than the Millennium-III parts (which are used in the higher end models). In addition the keys are very short in length. All of these combine together to create a heavier feel.

A short key causes the touch resistance to increase very much as you play towards the back of the key. You can try this, just play a note repeatedly with your finger at the front of the key, then move back while you keep playing and you will feel it get heavier. This alone can be the cause of the heavy feel.

My recommendation to you is to play other Kawai pianos, and talk to your dealer about changing to a larger size piano. Even the new GL-10 (which is almost the same size as the GM-10K) has slightly longer keys and the M-III action, so it feels much better for a pianist who wants an action that is easier to play. But the GX grands will be even better - the hammers are lighter, the keys longer, and the installation of the key weights is done in a more sensitive way. In other words, you need to choose the piano that is right for you! You can try having your piano modified to improve the touch, but the limitations of the action in this small piano might still not give you what you are looking for.

One important source of friction overlooked by techs is the key balance rail hole. Easing the sides of that hole often results in a noticeable decrease in perceived key down weight and improves repetition as well. Alcohol and water on the hammer flanges on Kawai has worked for me as well. I'd have someone reduce the friction in the action as much as they can. If still too heavy, take weight off the hammers combined with battery voicing to move the tension in the hammers and increase the volume. If still not good - I'd agree with Don's recommendation to trade up to a piano with a lighter touch.

Reducing the bump of let off can make the keys feel lighter - perhaps your tech was trying to do that by adjusting.