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I just made a thread in the digital piano subforum, but I thought it would be a good idea to ask it here, as this is where the techs are.


I'm wondering if it's possible to lighten up the touch of a wooden kawai dp action a bit.


[Linked Image]

Say you stick some small weights on the non-visible parts of all the keys, would the result be a lighter action, or would it mess the action up?

I could imagine the touch becoming lighter, as the weights would help the keys go down easier. On the other side of that coin I guess the keys would also return a bit slower. I don't know if it's a bad idea to add extra mass to the keys in the first place, but it wouldn't be much.


Worth a try? Stupid? Something inbetween? any idea's?

It is an idea that could be tried and is easily reversible.

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I don't think you would make the piano nicer to play by adding mass to the keysticks. But I'm not a rebuilder. Doubtless others will be able to provide a more informed opinion.

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Wooden kawai action is a very good candidate to experimentation, but first you have to know what you mean by "lightening up action", you mean static weighting or inertia or both? By adding weights in front portion of the key you will decrease static weighting and slightly increase inertia, to decrease inertia you have to lighten the hammers or change leverage ratio.

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Originally Posted by ambrozy
But first you have to know what you mean by "lightening up action", you mean static weighting or inertia or both? By adding weights in front portion of the key you will decrease static weighting and slightly increase inertia, to decrease inertia you have to lighten the hammers or change leverage ratio.

Hmm, I don't know actually.

I just noticed some parts of a piece I'm learning at the moment are easier to play on my yamaha u3 and looking for something that I could easily try, this idea came up.

The dp is a vpc-1. It's action feels a bit on the heavy side, which I think makes some things harder to play, but I don't know if that's the static weight or inertia.

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I know people who have both had their actions lightened and made heavier. Both happened to be college professors. In both cases they were grand pianos, though, and weights were always removed; just from different places depending on heavier or lighter.

The trick here is that while your digital piano has an action, you do NOT have hammers and such in that model? Some have actions and hammers, and some have actions that hit digital points and no hammers.

I bring this up because you have much fewer options for where you want to adjust the weighty feel. I think removing wood after the fulcrum would be better than adding weights where your fingers go. Either way, you could really mess stuff up.

Now that that’s out of the way, why do you want to lighten your action? Generally a heavier action can give you more control for extremely fine control of sound, but don’t confuse “heavy” with “stiff”. But then some people want a light action because they call it a “fast” action. To each their own. I used to have to play recitals several times a week on a Steinway D from 1979 with an action incredibly heavy and I loved it. Another time I played a Bosie with an action so light I could barely feel the keys and I hated it.

Just some things to think about before you mess with your digital piano. Keep in mind that your instrument is of great quality to start with.


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Originally Posted by U3piano
Hmm, I don't know actually.

I just noticed some parts of a piece I'm learning at the moment are easier to play on my yamaha u3 and looking for something that I could easily try, this idea came up.

The dp is a vpc-1. It's action feels a bit on the heavy side, which I think makes some things harder to play, but I don't know if that's the static weight or inertia.

In reality only thing you can do without serious modifications is to reduce static weighting by adding a weight in front portion of the key, I suggest adhesive stick on wheel weights for cars
[Linked Image]
they have adhesive tape so they can be removed if you dont like the result. (and they are dirt cheap)

If you would take downweight measurements and pictures and measurements of your action, I could calculate for you where and how many of these weights should be glued to get some sensible result.

SonatainfSharp Kawai VPC-1 has hammer action, no confusion there wink

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Originally Posted by ambrozy
In reality only thing you can do without serious modifications is to reduce static weighting by adding a weight in front portion of the key

Do you mean adding the weights on top of the non-visible parts of the keys (the wooden looking parts), like I initially thought of?

Quote
I suggest adhesive stick on wheel weights for cars

Good tip. But looking at the picture they might be too wide for a key? Ill see if i can find some information about that.

Quote
If you would take downweight measurements and pictures and measurements of your action, I could calculate for you where and how many of these weights should be glued to get some sensible result.

Very kind of you to offer this. I actually do have a set of measuring weights so i'm able to do this if you would tell me what and how to measure things exactly. I find this idea pretty interesting!

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Originally Posted by U3piano
Originally Posted by ambrozy
But first you have to know what you mean by "lightening up action", you mean static weighting or inertia or both? By adding weights in front portion of the key you will decrease static weighting and slightly increase inertia, to decrease inertia you have to lighten the hammers or change leverage ratio.

Hmm, I don't know actually.

I just noticed some parts of a piece I'm learning at the moment are easier to play on my yamaha u3 and looking for something that I could easily try, this idea came up.

The dp is a vpc-1. It's action feels a bit on the heavy side, which I think makes some things harder to play, but I don't know if that's the static weight or inertia.
Are you using the VPC-1 with Pianoteq? If so have you experimented with calibration. Of course it does not effect the downweight but proper calibration will prevent you hitting the keys too hard to get the volume you want. I use Pianoteq 6 Standard version.


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I'm from europe and here are available 5g and 2.5g weights with dimensions of 12x20mm, 12mm is a perfect fit for piano key.

[Linked Image]

Unfortunatelly I don't see much space here, you can probably add one 5g weight per key where I shown above, it will give you 4-4,5g reduction of downweight.

But first you have to measure downweight and upweight, downweight is a least amount of weight that will cause key to go at least halfway down (on grand piano it is down to just before escapement but digital piano will behave differently), and upweight is the max weight that a key is still able to lift to its resting position. After you carefully place a weight on a key you should tap slightly under the keyboard to break static friction in action, if there is too much static friction measurements will not be reliable. Acoustic pianos should have downweight of 45-60g and upweight at least 20-30g, difference between downweight and upweight should be 20-30g (sliding friction 10-20g), In digital pianos there is not much friction usually so your difference may be 0-10g only, I personally would aim for a downweight of 45-50g for this instrument

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corrrection:
difference between downweight and upweight in acoustic should be 20-30g (sliding friction 10-15g)

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I did some measurements (around middle c) and what your saying seems about right, and it also confirmed the vpc-1 is heavier than my u3.

U3 - Downweight +/- 50 gram, upweight +/- 28 gram.

VPC-1 Downweight +/- 60 gram, upweight +/- 52 gram


Your also right about there not being much space on top of the keys, the picture I posted above is a grand feel action, looking at that I forgot the rm3-ii action in the vpc-1 is shorter.

Hm, I don't know about sticking weights under the keys, because I don't know if they will stick well enough to stay on there, but I could try. I could open up the vpc-1 to measure how much space there actually is left in front of the balance pins to see if I can put a weight on top, but even if there would be space enough I guess i would have to stack a few to get the same effect, as the position is so close to the balance pin.

I do think I would like it if I could decrease the downweight to ideally 45-50 gram, or maybe 56 gram if that's all the situation allows for. Maybe a 10g weight would fit under the keys as well?

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It is way to close to balance pin to put a weight on top, from what I can measure from that action photo you will need 100g there to get 10g downweight reduction.

You should do measurements in bass and treble also to see how this is weighted in factory, because there are most probably graded hammers in that instrument and if they just put same counterweights on all keys you will have more downweight in bass than treble, acoustic pianos also have heavier hammers in bass but static weight is the same for entire keyboard (if there is difference it is due to friction) and only inertia is different for treble and bass. Digital pianos needs to be cheap in production so they ommit as much steps in production as possible

I can't guarantee that those car whell weights will stick well to wood because I was using it only on top of keys in grand piano, but they have very strong adhesive

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Perhaps you could fit this with a Pitch Rail touch weight adjustment rail.
Contact SJONES@PITCHLOCK.COM for his advice.


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Originally Posted by ambrozy
It is way to close to balance pin to put a weight on top, from what I can measure from that action photo you will need 100g there to get 10g downweight reduction.

If possible would actually putting 100g there be comparable to sticking 10g under the keys like in your picture? Or would this result in extreme increase in inertia?

I have spotted some 100g truck wheel weights. blush

Originally Posted by Ed Sutton
Perhaps you could fit this with a Pitch Rail touch weight adjustment rail.
Contact SJONES@PITCHLOCK.COM for his advice.

Interesting!

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Originally Posted by U3piano
Originally Posted by ambrozy
It is way to close to balance pin to put a weight on top, from what I can measure from that action photo you will need 100g there to get 10g downweight reduction.

If possible would actually putting 100g there be comparable to sticking 10g under the keys like in your picture? Or would this result in extreme increase in inertia?

I have spotted some 100g truck wheel weights. blush

Originally Posted by Ed Sutton
Perhaps you could fit this with a Pitch Rail touch weight adjustment rail.
Contact SJONES@PITCHLOCK.COM for his advice.

Interesting!

It is quite the opposite, 100g placed near the balance pin has LESS inertia than 10g placed at the end of the key, it is counterintuitive but it's true, moment of inertia is linearly proportional to mass but quadratically proportional to distance from pivot point (in other words to speed), but the 10g at the end of the key has very little inertia compared to the hammer anyway

Something like touch rail will be worth considering, but there's nowhere to mount it in that kawai

[Linked Image]
It is designed for grands and it replaces key stop rail

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Originally Posted by ambrozy
It is quite the opposite, 100g placed near the balance pin has LESS inertia than 10g placed at the end of the key, it is counterintuitive but it's true, moment of inertia is linearly proportional to mass but quadratically proportional to distance from pivot point (in other words to speed), but the 10g at the end of the key has very little inertia compared to the hammer anyway

Ok! so if I understand correctly, if I could manage to fit 100 gram weights in that spot near the balance pins, other than looking ridiculous, this should cause no negative side effects worth mentioning?

If this is correct I'm opening it up to measure the available space and see if I can find suitable weights. It still seems like an easier option than trying to fit weights under the keys to me, but as I open it up I'll get a better idea of how doable that would be as well.

I think ill pass on the touchrail. I like getting creative but I'm looking for a simple, reversible solution here.

(Btw your of great help ambrozy, thank you so much!)

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It is not really possible to put weight there, there is 12x12mm spot right after keytop ends so if you needs 100g you will need 12x12mm x 36mm tall tungsten block or 61mm tall lead block or 88mm tall steel block. lead and steel will be to high and tungsten is rather unobtainable.
Personally I would drill that keys and install oldshool leadweights

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Ok so to look at the possibilities I opened it up and took some keys out, and you were right again: there is no space to put 100g weights on top of the keys near the balance pins.

[Linked Image]

Taking the case that has to be put back in place into account there would be just 10mm left, which is not enough. So no option there.

Unfortunatly there is also no space in the locations you drawed in the action picture, as there is hardly (maybe yes, maybe no) enough space in height, and if I would use the adhesive to stick the weights on they would have to stick to the flat surface and that's where the key cushioning is placed:

[Linked Image]

The only location possible would be where the original bass-end counterweights are placed, which is again, very close to the balance pins:

[Linked Image]

These counterweights are screwed in, here's the bottom of a key:

[Linked Image]

Another idea came to mind, something that would work like the touchrail, but this wouldn't be such an "easy" solution either. But, the thought is maybe I could replace the cushioning onder the end of the keysticks with springs.

[Linked Image]

But actually that would probably take quite a bit of figuring out how to exactly make that happen, what kind of springs to use etc, and I don't really like the idea of springs anyway.


So I guess this isn't going to be as easy as I had hoped. I would rather not start drilling into the keys, but on the other side that would be a perfect solution of course, and I am fairly confident with tools. Is this doable for someone who does have experience with tools, but has never done this? Or should I just ask the tech that usually maintains my u3?


If I would rather not start drilling in the sides of the keys, another option would be to drill a very small hole in the bottom of the keys, and drill holes in the weights to screw them to the bottom of the keys, same as the original counterweights. In that case i might actually find weights that would fit in the locations you drawed (because they wouldn't have to stick on the flat surfaces), but they would be 5g max and I don't know if that's worth it as I would like to have this action around 45-50g downweight.

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I don't know that adding weight to the front part of the keystick will get you the result you want. I would be afraid it would just add more inertia to the system, thus making your key feel even heavier. For example, the downweight of my Kawai MP11SE is around 60-61g, whereas the downweight on my acoustic is 50-55g. However, my acoustic feels heavier to play. I believe this is due to the increased static friction from acoustic action parts, but also the increased inertia from the lead weights in the acoustic keystick, which the digital keystick doesn't have. I'd also be concerned your key return would be slowed if you added weight.

I believe the only real solution to lighten my acoustic would have been to reduce hammer weight, then remove a corresponding amount of front key lead. However, I installed a Touchrail instead, and that has done the trick. Since a Touchrail won't work in a digital, I can only think of lubrication. How old is your digital? Any way to lubricate the action parts? Maybe a dry lube like WS2 would help any metal/metal or plastic/metal friction points.


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I don't think I've seen anyone target the "hammer" weights on this digital...

I would think that might be the area to target for removing some material? Looks like a high ratio, so it might not take much to make a difference.

Ron Koval

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