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Hi everyone,

I've perused Piano World for the last couple years, but I'm now officially a member smile

I'm currently doing a bit of regulating and voicing work on my early 1990's Kawai NS20a upright, and have a touchweight question that I thought someone here might be able to help me with.

The downweight seems fine across the keyboard (around 48-52 grams roughly), but the upweight seems high, around 31-35 grams. It gives a feeling like the keys suck up with your fingers when playing. Not necessarily bad, just feels a little uneven when trying to play very delicately.

I'm not the greatest player, nothing with high repetition, so I'm wondering if this is best just to not mess with? I'm assuming most people would rather have an action with a nice downweight and heavy upweight than the other way around.

The only thing I can really think of is that the center of gravity is actually a bit off, meaning the "correct" Kawai spec downweight should be a little higher, which would make the upweight a little lighter.

The keys only have a single lead at the back, so it seems a bit excessive to remove all 88 leads, fill the holes, and re-weigh off the entire set of keys.

Is there anything else I should specifically look at, or any little hacks that might only reduce the upweight and not effect the downweight?


____

The only other issue is a bit of hammer blubbering, but it doesn't really happen when actually playing, only when I sit there and very slowly press a key, basically the hammer striking again before the jack can get out from under the hammer butt. I honestly think that is more so me being overly picky and trying to make it blubber on purpose. Most uprights will blubber a little when playing a single key extremely softly and slowly, correct?


Thanks for the help!
Josh

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I've said this recently on another thread, but vertical keys are weighted on the back for a good reason: so the key will repeat well. Many companies saved money by not weighting the back of the keys; this can make them repeat poorly. They can hang up at the slightest encouragement. That's why technicians sometimes stick on Jiffy weights.

So, sure, you can remove weights from the back of your keys. Just be warned it won't do the action any good.

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"Hammer blubbering"--did you mean bobbling?

Yes, it's a problem with many modern pianos. There are several theories having to do with spring strength. Check to make sure you have taken up the lost motion and that the blow distance is such that the jack actually clears the hammer butt as you press down the key.

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sorry, yes I meant bobbling.

lost motion has been taken up, but now that I look at the blow distance, it seems a little longer than I thought I had measured (looks to be around 50mm). I'll shorten this some and take up the lost motion after and see if that helps.

As far as your previous comment on the action, I think I'll stay away from messing with the key weight and keep the heavier upweight in favor of the favorable downweight. Thanks for the helpful nudge in the right direction.

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Fourcorners,
Don't simply adjust blow distance by numbers. You have to experiment with some samples and actually look at the jack. Here's what to do:
1. Get 3 rubber mutes and shim up the hammer rest rail a little.
2. Using some keys as samples, take up the lost motion.
3. Now, get right in there and LOOK at the jack: it should fully escape from the hammer butt, yet not go out so far as to hit the felt-covered rail just in front of it (or something could eventually break...).

After you determine the best blow distance to achieve this, you can the shim the contact points with firm felt. Then you have to set letoff if necessary and then checking.

Theoretically you would start with key height and dip, so hopefully those are close...
Sometimes you can regulate a piano by jumping midway into the sequence, but sometimes you have to back up and go from the very beginning. For technicians (like me), it can come down to practical things like piano condition, available time and budget constraints, and whether we want a fine regulation or a "just get it working" job. Fine-regulating a keyboard can take a few hours.

Last edited by Scott Cole, RPT; 05/04/22 05:51 PM.
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Can I add that it would be wise to stick with just one test note until you have looked at every point in the play sequence. For iff you alter one dimension you may need to alter so much inc dampers, for instance. In my life I very often find that a previous "regulation" has only adjusted one part. This is good because I find that returning that to the recommended dimension restores a complete action by just attending to that one part. If you change lots across the whole keyboard you are raising the possibility of alot of work to get it back. Stick to one note, get it the best you can then leave it and check over a few days playing before moving to another note. Then check that for a few days.
Sorry to sound pedantic but I see so many well meaning "regulations" that take ages to put back together.


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Originally Posted by Scott Cole, RPT
Fourcorners,
Don't simply adjust blow distance by numbers. You have to experiment with some samples and actually look at the jack. Here's what to do:
1. Get 3 rubber mutes and shim up the hammer rest rail a little.
2. Using some keys as samples, take up the lost motion.
3. Now, get right in there and LOOK at the jack: it should fully escape from the hammer butt, yet not go out so far as to hit the felt-covered rail just in front of it (or something could eventually break...).

Wow, moving the blow distance 6-7mm closer to the strings made a huge difference! Seems a bit close, around 39-40mm but I guess it doesn't matter if it works better. It is funny how easy it is to think that going by empirical values creates a consistent outcome, but I guess the consistency doesn't matter if you don't like the results, haha. Before the jack would clear the hammer butt when playing, but would tend to rest right at the top most edge of the hammer butt buckskin. Now it fully kicks out from the butt in a single motion (with no skipping) and has about 1-2 mm space between the jack and butt, and also doesn't go close to the felt-covered rail.

The touchweight is now a bit too light now, as the hammers have much less gravity to fight. I'm not the biggest fan of adding a zillion jiffy weights to every single key... luckily it should be fairly simple to add just a single small lead to the back of all the keys.

Last edited by fourcorners; 05/05/22 12:28 AM.
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That's too close. On a note you haven't changed yet, how far from the strings is the hammer when resting on backcheck?
What dimension is the setoff?

Last edited by N W; 05/05/22 04:01 AM.

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2 mm of clearance between jack and hammer butt is probably too much.

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Originally Posted by N W
That's too close. On a note you haven't changed yet, how far from the strings is the hammer when resting on backcheck?
What dimension is the setoff?

You are saying 39-40mm is too close for hammer blow distance, correct?


When you say "how far from the strings is the hammer when resting on backcheck" you mean after playing a note, correct? I had already gone through the main regulation process a few days ago, so all the backchecks were set to have about 16mm distance after playing a moderate key blow (this is before moving the hammer rest rail, when the hammer blow distance was closer to 50mm).

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Originally Posted by Scott Cole, RPT
2 mm of clearance between jack and hammer butt is probably too much.

It is actually probably less than 1mm, was just trying to make the point that it clears the butt and also doesnt get close to hitting the felt-covered rail.

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Originally Posted by fourcorners
Originally Posted by N W
That's too close. On a note you haven't changed yet, how far from the strings is the hammer when resting on backcheck?
What dimension is the setoff?

You are saying 39-40mm is too close for hammer blow distance, correct?


When you say "how far from the strings is the hammer when resting on backcheck" you mean after playing a note, correct? I had already gone through the main regulation process a few days ago, so all the backchecks were set to have about 16mm distance after playing a moderate key blow (this is before moving the hammer rest rail, when the hammer blow distance was closer to 50mm).
Let me put it this way.
If I came to your piano with your original dimensions and found your bubbling on very gentle touch the first thing I would check would be the setoff as that felt often compresses as the piano wears in leading to a setoff which is a little too close. So I would back that off a tiny amount and see what was what before altering anything else.
What's that dimension now?
I feel from your comments that you are going/have gone down the route I was trying to warn you about.what you call " a bit of regulating" is almost certainly "deregulating" as you don't have the experience to know what to look for first. The more you adjust, the further away you are likely to be going.
Just my opinion, but why not hire someone who knows what to do?


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Originally Posted by N W
Originally Posted by fourcorners
Originally Posted by N W
That's too close. On a note you haven't changed yet, how far from the strings is the hammer when resting on backcheck?
What dimension is the setoff?

You are saying 39-40mm is too close for hammer blow distance, correct?


When you say "how far from the strings is the hammer when resting on backcheck" you mean after playing a note, correct? I had already gone through the main regulation process a few days ago, so all the backchecks were set to have about 16mm distance after playing a moderate key blow (this is before moving the hammer rest rail, when the hammer blow distance was closer to 50mm).
Let me put it this way.
If I came to your piano with your original dimensions and found your bubbling on very gentle touch the first thing I would check would be the setoff as that felt often compresses as the piano wears in leading to a setoff which is a little too close. So I would back that off a tiny amount and see what was what before altering anything else.
What's that dimension now?
I feel from your comments that you are going/have gone down the route I was trying to warn you about.what you call " a bit of regulating" is almost certainly "deregulating" as you don't have the experience to know what to look for first. The more you adjust, the further away you are likely to be going.
Just my opinion, but why not hire someone who knows what to do?

The first thing I addressed was the setoff, and I essentially had to set it much too large to get it not to bobble when playing with a gentle touch.

I totally agree that hiring a piano tech is the best route, as I know they are trained to do this exact thing, but I've always been a person that enjoys learning and taking on complex tasks myself, as I find joy in both the playing and understanding the mechanics of instruments (for example, I enjoy repairing old synthesizers as well). I also maybe have given the impression that my piano plays very poorly, and that isn't the case.

I also don't want anyone to think I'm essentially coming here to ask questions as a way to avoid hiring a professional tech, it is more so that I've observed how amazingly generous and helpful this community is, and thought it would be a great place to expand my knowledge of regulating a piano.

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Fair enough. So I've asked a couple of times but you haven't said yet, what is your setoff now?

How are the hammerbutt felts for instance...maybe the jack is sitting too far in if they have compressed?

There are so many things to take into account before making big changes to dimensions....

Last edited by N W; 05/05/22 02:51 PM.

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Originally Posted by N W
Fair enough. So I've asked a couple of times but you haven't said yet, what is your setoff now?

How are the hammerbutt felts for instance...maybe the jack is sitting too far in if they have compressed?

There are so many things to take into account before making big changes to dimensions....


Sorry about that. Anything less than about 6mm for let-off I get some bobbling, this is with hammer blow distance at about 45mm, loss of motion taken up, key height of about 20mm, key dip of around 10mm.

It could be compressed hammer butt felts. This piano was purchased new in the 90s, 1 owner up until i bought it 4 years ago. She was a piano teacher, so they could very well be compressed a bit too much. Overall the piano was kept in very good shape though.

I'm not entirely sure what the correct thickness should be for the hammer butt felts, but I could remove a hammer butt and try to measure the felt with calipers. It would also give me a chance to check the butt flange.

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Upweight is fine. You want it high for faster repetition. It gets higher due to wearing in. What is not working right is your ability to get your fingers out of the way as you release keys.


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Originally Posted by N W
Fair enough. So I've asked a couple of times but you haven't said yet, what is your setoff now?

How are the hammerbutt felts for instance...maybe the jack is sitting too far in if they have compressed?

There are so many things to take into account before making big changes to dimensions....

They don't seem particularly worn out, but maybe I'm wrong.

Here are 2 images...

https://i.ibb.co/BrVFNvM/Screen-Shot-2022-05-05-at-3-46-12-PM.jpg

https://i.ibb.co/mTgXLnQ/Screen-Shot-2022-05-05-at-3-46-06-PM.jpg

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Maybe something to do with weak hammer return springs, meaning not enough tension to pull the hammer away fast enough?

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Originally Posted by fourcorners
Originally Posted by N W
Fair enough. So I've asked a couple of times but you haven't said yet, what is your setoff now?

How are the hammerbutt felts for instance...maybe the jack is sitting too far in if they have compressed?

There are so many things to take into account before making big changes to dimensions....


Sorry about that. Anything less than about 6mm for let-off I get some bobbling, this is with hammer blow distance at about 45mm, loss of motion taken up, key height of about 20mm, key dip of around 10mm.

It could be compressed hammer butt felts. This piano was purchased new in the 90s, 1 owner up until i bought it 4 years ago. She was a piano teacher, so they could very well be compressed a bit too much. Overall the piano was kept in very good shape though.

I'm not entirely sure what the correct thickness should be for the hammer butt felts, but I could remove a hammer butt and try to measure the felt with calipers. It would also give me a chance to check the butt flange.
I would suggest that 10mm isn't enough keydip for this piano. I would suggest removing a front rail punching or two on one test note.allow say 12mm or maybe even a bit more. See what happens. Adding keydip also makes the action feel much lighter which you may like. Just try it and see what you think.
Nick


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This is becoming a can of worms for the OP.

I will say that bobbling is definitely an issue on many modern verticals, but I don't think it has much with to do with how much the jack escapes. Yes, having letoff (or setoff) further away helps the symptoms, but it's not the cause and unfortunately makes soft playing more difficult. In addition to the strong springs used in modern verticals, I've also wondered if the size of modern jacks from front to back make it more likely they'll get hung up than older jacks, many of which seem to present a small profile at the tip. Just picture a screen porch door that closes too quickly and always gets you on the way out--you may be able to just dart through alone, but not carrying something.

Don't get too hung up on measurements--do what works.

Last edited by Scott Cole, RPT; 05/06/22 11:43 AM.
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