Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Non uniform hammer travel distance

The best way to answer your question is to ask Hailun, and the best thing to do is follow rxd's advice.

I agree. Standard procedure for doing this if it becomes necessary is through the dealer.

I'll ask my dealer then. I just thought that maybe you guys have seen this before. No harm in asking.

And there has been no damage to the piano whatsoever. In fact, the repetition is better now that the springs have been regulated.

And there is no competent technician in my area. So I take care of my piano. My training in my career has instilled in me patience, attention to detail, and to observe the dictum 'primum non nocere' and not to do the 'committing step' if you cannot reverse it when necessary. So I guess I have the aptitude for this. I am just gathering insights from experts here who have the experience and who could share pearls of wisdom.

Presently, I have no complaints with touch and tone, but was just wondering why the raised hammers.

Thanks, everyone!

You are just lucky, famous pianists have asked for this setting to get a faster instrument.

The dealer looked it over probably and adjusted a few things so your piano works properly.

Satisfaction noted. There are huge patches of the world where there is no technical knowledge of pianos. This forum, hopefully, is doing much to begin rectifying that situation.

It is the hidden details, those not mentioned in any of the books, that can wreak havoc if not attended to, plus knowledge of how an action changes, both seasonally and over time, is a great asset.

I am concerned, however, that the raised hammer line may be stressing the jacks to breaking point. You do mention a 9mm dip which might minimise the problem. Just check that there is free play between the jack tender and the cloth of the adjusting button when the key is held down with some pressure but the hammer not in check. If there is no play, lower the hammers by means of the capstans until there is some play, keeping the hammer line level but not low enough for the hammers to catch on the backchecks on the way up.

While the action is not designed for those dimensions, it can work well with a slightly shallow dip if compensating adjustments are made elsewhere. I have just described the main one. It won't disturb what you have already set up too much but is important. You might finish up with 44-45 mm anyway. The bass is probably ok. 9mm is an ancient standard key dip dimension, still preferred by some.

The fact that you had to increase spring tension may indicate a problem with excessive humidity.

I suspect the glide bolts may be out of adjustment but from what you describe, not in a damaging way.

The back checking may be low but again, from what you describe, not damagingly so.

The jack clearance is the most important.

We used to say that in the country of the blind, the one-eyed man is king but it's probably not PC any more.

Could be a previous prospect requested this.
An interesting giveaway might be an additional strip of very thin cloth under the back rail cloth on the action frame. This is the usual way of reducing dip quickly. The compensating adjustments still had to be made.

Another reason to always refer through the dealer.

Thank you rxd for your clear and succinct summary. Your two posts are spot on.

Thank you, rxd. I learned a lot.

I *did* check the jack clearances with the front part of the balancier slot with key fully pressed and hammers swung forward. I could definitely see a clearance there.

When I lowered the hammers some of them were already touching the rail. Raising them again to original position made the distance from hammer rail same with the bass hammers.

I dont know the configurations of this particular model. A hammer rest rail is generally not necessarily as reliable a guide as individual hammer cushions are since it may have been adjusted to suit the hammer line with any and all of its vagaries. Make sure the rest rail is equidistant from all the wippen flanges first before using it as a very rough guide for hammer height.

The most useable measurement is from the strings. This should produce a reasonably straight line in all the hammer shanks. . Not perfect because agraffes vary almost imperceptibly in height because they have to be shimmed to varying degrees to make them both snug and square. Also there may be very slight variations between each section.

The bass hammers, you will notice, are bored at a different length to compensate for the difference in string height. This will make all the shanks form a reasonably straight line but with the bass hammer heads a few millimetres higher than those in the treble in order to maintain an even regulation. All this is done on a preset jig in the factory giving an average of the slight variations.

Hello first thing that comes to mind is that moisture thickened the backrail cloth, at the same time key dip lowers and the hammer raise. 4-5 mm seem a lot but who knows. RXD said the most important thing you may verify. Also visually the way the shanks are at rest can be more or less evaluated.

The worst situation would be a warpage or the keybed with moisture. I have seen that and not under terrible conditions and not on a medium priced grand. The quality or the keybed was in cause and itoor courser bcoffet. s very difficult to correct.. (once moisture was back for accepteable conditions with DC and undercover, situation was a little better but the whole keyframe had to be adapted, with scraping the keybed as well then compete keyboard regulation ) that grand is not far from a large river.
Moisture is high all year long in the 55 60% range usually and more in spring and in a good house well isolated.

Best wishes.

Factory data may help of course but there is so much to look at.

Are you absolutely sure that this isn't a measurement mistake?

One way to roughly double check, is to measure the difference in height between the bass and treble strings, and compare that to the difference in height of the bass hammers and the treble ones. From your description, I would expect the bass hammer line and the treble hammer line to be pretty much the same, is that the case?

There's just a bit of an alarm bell going off here that the picture isn't quite accurate. Describe exactly what you've measured, and where. Which notes, where on the hammers, where on the strings etc. Is the hammer travel distance uniform throughout the bass, and also throughout the treble?

The bass strings are higher on the horizontal plane compared to the treble strings. But, yes, the bass hammers are more or less in line with the treble strings.

Yes, the travel distance is uniform among the bass strings at 45 mm, and also among the tenor and treble at 40 mm.

I measured the distance from the underside of the string directly above the hammer, to the strike point of the hammer directly below. Is that correct?

Yes. And, if you do all other steps (key height, dip, let-off, drop, etc.), you can adjust after-touch last via the method I described before (using a correctly sized front rail punching, 300g weight, and adjusting the capstans). If everything is done correctly, this will give you proper hammer blow distance.

Thanks.

So if my measurements are correct, my question remains to be answered.

Would a pro technician set blow distance differently for the bass compared to the rest, or is this an unacceptable practice for you pros?

Again, may I emphasize that I have no complaints with the piano and it is still blowing me away and I have a difficult time leaving for work. And I have no intention of changing anything again because I so love the way it feels. Especially that the repetition is so improved after the springs were adjusted.

I agree and that is exactly why I'm asking this question.

Again, I didn't say this. What I said was that the action seemed heavier and the *aftertouch* was messed up.

At the first shop I worked at, we routinely set preliminary blow to 44mm in the treble and 47mm in the bass, so yes.

Finally!

May I know the reason for this?

Am so interested in the answer but I may not be able to check the forum for a while. I'm on internet access in my office which has electricity but will be driving home shortly where we do not have power due to the typhoon.

I can see no reason or benefit for the bass to have a different blow distance. You will not find this in any specs for any manufacturer - In fact it would go against the specs for every piano in production.

That being said, you will find professional techs who have all sorts of strange ideas about regulating pianos. The PTG makes some effort to promote standards, but there is no real reinforcement of such.