Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Lowering key height to decrease touchweight?

I've been reading through Steven Brady's book, Under the Lid. He states in the regulation section that all things being equal, a higher key height will result in a higher touchweight due to the position of the capstan with regards to the wippen.

Just curious, has anyone tried decreasing key height 1-2 mm to reduce touchweight? Or would this have so little of an effect that it wouldn't be worth it?

It would be a pretty big job and would have little to no effect that I can see. I can think of a whole lot of trouble that it would introduce, but for the sake of brevity I'll pass on the specifics and discourage it or any kind of messing about with your pianos' action geometry.

I would reiterate that the cost/benefit ratio is way too high. Fogetaboutit!

Pwg

Well I’ve already installed new balance rail punchings that I split myself to alter the leverage. I had to relevel all of the keys and regulate the action. So I’m confident I could do it . But it sounds like it wouldn’t have much of an effect. This action (1998 M&H A) has a very heavy touchweight due to leverage problems (confirmed by an RPT) and probably needs the capstans moved, I’m just trying to avoid doing that if possible. I already have a touchrail as well.

Thanks.

I have not tried it but in principle it should work.
Many times I have changed action ratio in order to adjust touchweight to a target as well as be able to remove excess key lead.
The typical modification is to remove the key capstan, plug the hole and re-drill/replace capstan only 1 to 2mm forward. This change in leverage has a rather dramatic effect on touchweight.
So as a key rotates by lowering the key height, the key capstan would move forward by a small amount.
This small amount would indeed effect the touch.
If the key height and travel were already set correct, It should not be a big job to remove the same size punchings from balance and front rails in order to maintain even key height and travel while at the same time lowering key height slightly. Maybe only an hour or two at most?
All should work ok that is unless the keytops at the front are too close to the keyslip.
If you have a gram weight set, try a sample note or two. You may be surprised at the effect.
Action friction needs to be correct too.

Thanks for the response. I also thought it shouldn't take too long - max 3 hours if the key level doesn't need too much refinement. I may try it on a few keys just to see what effect it has on DW and UW. I think there is enough height at the key slip to make the adjustment without causing problems.

The split balance rail punchings also made a pretty big difference (the pre-split ones didn't do much - so I cut them off behind the balance rail and glued them to the keys). But the touch is still heavier than I would like.

The TouchRail helps - but it seems to help most with just the initiation of key movement - as the key moves deeper the resistance increases because there is less spring tension. So the action still can feel heavy.

My technician quoted me $500-$700 to move the capstans. My wife wasn't thrilled with that idea (I've already spent plenty of money on this piano) - but if it solved the problem I would consider it. He's a very good technician and I'm sure would do a good job. If I owned a drill press I may have attempted it myself (thankfully I don't, because I would probably ruin the piano).

Thank you for tolerating my amateur questions!

asb37, I am sure it's not a case of 'tolerating', when a pianist with a real technical interest in his or her piano, poses intelligent and interesting questions!

What would be less well-tolerlated, is the kind of question where someone comes on here and says something like "I don't want to pay a technician - what size of socket wrench or type of radiator key should I use to tune my own piano??"

I will add one more thought: If it is done right, $500. - $700. US - is a good price for moving key capstans.
Moving the key capstans itself is not too lengthy but: investigating why to move them, how far to move them, what it will accomplish, will removing and or rearranging key leads and balancing the touch be part of it, follow up regulation which usually requires a full re-regulation of key travel, let-off, drop, jack alignment, rep lever height, hammer blow distance/hammer line, possibly checking, etc.
there could be limiting factors like will the position of the whippen heal allow the capstan to be moved so it still contacts felt and the the wood edge of the heal?
Sometimes I will move the whippen heal but like on a NY SS - the heal is part of the whippen and cannot be moved.
I usually charge quite a bit more than this. It can get very involved.
There is another option which I dont care for personally but it gets results and is less lengthy and that is reducing the mass of the hammers.

Thanks for the response. I also thought it shouldn't take too long - max 3 hours if the key level doesn't need too much refinement. I may try it on a few keys just to see what effect it has on DW and UW. I think there is enough height at the key slip to make the adjustment without causing problems.


My technician quoted me $500-$700 to move the capstans.
[/quote]

Greetings,
If you want to lower your key height, for an change in action performance, I think you are wasting time, but it shouldn't waste too much. Place a 1 mm shim under your back rail cloth. This will lower all the keys 2 mm, and allow you to remove 2 mm worth of front punchings to keep your dip the same. All you should have to do then is lower your capstans to restore your hammer line.

If you elect to remove balance rail punchings to lower the key height, you will need to lengthen the capstan to keep the same hammer line.

I wouldn't dream of doing this for that price, since you will need to measure, assess, disassemble the action, fill holes, drill holes, install capstans,(great time to make the switch to WNG lightweight anodized ones), re-regulate, and return it. As mentioned earlier, the time it takes to accurately measure enough dimensions to move capstans properly is considerable and costly. However, it is not nearly as costly as not taking the time.....
Regards,

Wouldn't it be easier to get a pair of those hand strengthening devices, you know, the springie things that you squeeze?

I’ve experimented different approaches to decrease touchweight myself before, including changing key height, touchrail, reducing friction in the action parts, and cutting the balance rail punching.
Out of all, changing the keyheight was the most time consuming, mainly because you have to regulate the action so the aftertouch is right. The results was also the least noticeable one…
Touchrail worked pretty well for the downweight, but the upweight was compromised and I didn’t like that. It wasn’t terribly bad, but being an advanced pianist, it bugged me.
Reducing friction worked, but dynamic control was compromised greatly with the amount of touchweight I decreased.
Out of all, cutting the balance rail punching had the most significant result without much compromise (slight change in keydip), and is the approach I usually go for now

Very interesting. Many thanks for sharing your experiences with various approaches...

As for your favorite: By "cutting the balance rail punching" are you describing making a notch into the BR felt punchings (similar to the "Crescendo Accelerated" balance rail felt shape)?

If so, does this actually change the touchweight? Or is it that the cut-out (placed facing toward the piano player) provides the sensation of a lighter action as there's less balance rail felt material to compress when depressing the key?

Related to this, is it reasonable to assume that the upweight remains unaffected (which would be good news for preserving repetition)? If the "cut out" portion of the felt reduces some felt compression on the key's journey downward, it would seem to follow that it plays no further role once the key begins traveling upward - i.e., moving away from the missing portion of felt (that isn't there anyhow).

- OneWatt

Sounds to me like lightening the hammers would be a good place to start. I'm surprised some of you think that is more trouble than some of the other things being suggested. Is that because you are concerned about having to alter the key leads? Is it possible that this piano was designed to have lighter hammers, but the hammers were changed at some point with excessively heavy ones?

OneWatt,
yes, it's the same approach as the crescendo accelerated balance rail felt. The amount of felt cut determines how much downweight you want to decrease. The more you cut (more towards the middle), the more downweight is reduces. I've cut all the way up to half on a kawai upright once because of how ridiculously heavy those pianos are (client complained and was ok with me doing that.)

The theory behind this approach is to actually change the geometry of the key balance. When a key is depressed, the actually balance point is at the front of the BR felt punching, so by cutting it, you're theoretically "moving the BR pin backward", providing more leverage from the BR to the front of the key.

Ah, makes sense. It's like moving the fulcrum point backward on the BR by a small amount.

I imagine this necessarily has the effect of being a symmetrical change in leverage, i.e., reducing both the upweight and the downweight.

As an advanced pianist you might have noticed a slight give-up in repetition... did you feel the need to adjust repetition springs as a result?

- OneWatt

When I "Horowitzed" my grand, I also lowered the key height which I found too high, but this was not done to decrease touch weight. To get a very light and responsive touch, I slightly reduced hammer mass and modified other regulation parameters like damper timing, jack position, spring tension and so on.

I agree - seems to me that the simpler options are not being seen for the forest of technical procedures involved in major adjustments.

Not to put down your skills (I don't know your abilities), but regulating a piano- if it is not done properly- can actually induce a heavy touch...For instance, if damper regulation is not done properly (early lift), one can add a lot of weight to the keys...There are many other things involved in the regulation that affects touch-weight.

Just a point I thought I would mention.

Personally, removing mass from hammers just dont happen when addressing a typical heavy touch situation and heavy touch (lets assume friction and regulation are correct) is not necessarily disclosed by down and upweight gram measurements at the key fronts.
When I move key capstans to correct heavy touch the keys are always over-leaded, sometimes 8 to 12 key leads in bass tapering to several on the back side of the keysticks in the treble.
If I were to remove hammer mass, the down weight at the key front may go down but the touch would remain heavy because your fingers will still be pushing excess lead as opposed to hammer felt. Also, when excess key leads are removed, the upweight at the key front improves and the action is much more responsive. It just dont make sense to me to remove hammer mass in this situation.
Excess key leads is a statement that the action ratio needs to be corrected.
The opposite happens rarely, the down weight at the key front is high and heavy touch is the complaint but there are too few leads in the keys.
Adding some key lead is then the most simple solution.
I suppose there are situations where a tech installs a hammer set that is too heavy for that action but in my experience, heavy actions are geometry issues and hammer tapering/shaping happens prior to hanging.
Much good information in this thread about quick solutions but given excessive key leads, eventually geometry issues will need to be addressed.
As for removing hammer mass, this should be more related to tone and voicing issues - typically, but there are always exceptions and time spent on action analysis is essential "IMHO"!