Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Hammer Stroke Distance for Kimball Whitney 1978 spinet?

Reblitz says it's about 1.5 to 1.75 inches in spinets.

Indeed, most of my hammers are about 1.7-1.8 inches from the strings, with some of the high treble hammers close to 1.9 inches.

I couldn't find a website with the "Piano Action Handbook",
so I don't know the exact factory value...

Paul,

Let the piano tell you, after all the blow is really a function of action geometry.

My approach (and some will disagree mightily with me) is to start with the pianist's experience and that rests with key dip. First make sure the amount of key travel is appropriate (no more than .400") and then adjust the blow for the appropriate after touch.

Kimball can present all sorts of interesting manufacturing er issues. The hammer rest rail in all likelihood is not straight so you will need to shim part of the rail to achieve a uniform blow.

Good luck.

Well, what is the consequence of too long a hammer
stroke? Simply just too loud of a piano? That by
itself doesn't seem to be the end of the world, but
perhaps faster and deeper grooving of the hammer felts?

A beginner such as me will naturally try to follow
the procedure order given by Reblitz, but I'm sure it's
interactive in actual practice:

12. Set hammer stroke
13. regulate lost motion
14. Set key height
15. Level white keys
16. level sharp keys
17. Regulate hammer letoff
18. Regulate white key dip (here he mentions the aftertouch)

I started regulating lost motion, but stopped when I realized I skipped setting the hammer stroke. I'd rather
only do step #13 once, as it's quite tedious to turn the lifter wire screws on all 88 keys.

Set samples first to at least get some of the right answer. The problem with looking for "the right answer" with a Kimball is that more often than not, the quality control (both in the actual manufacture and raw material selection and preparation) is very poor. coincidently, I spent this morning doing exactly this on a 40 year old Kimball with a warped hammer rest rail. I set samples to see where everything should work reasonably well and am proceeding from there.

For samples use the outside white keys from each section.

So what hammer stroke did you find worked well?

Also, Reblitz recommends:

hammer letoff, 1/8"
hammer check, 5/8"

This PTG video approximately agrees:

https://www.youtube.com/watch?v=-zX0q0mZDRM

However, my spinet piano:

hammer letoff, roughly about 3/8" on most keys
hammer check, most around 7/8", with some over 1"

I find it hard to believe ALL the keys went out
of the recommend specification by that far, especially
on a piano I know was not used much. It would not
surprise me if this was about how it came from the
factory, which would support your claim of bad
quality control. I'm also fairly certain I'm the
first one to regulate this piano since the factory.

But once again, a hammer letoff of 1/8", and a hammer check of 5/8" are the right numbers, for a spinet too, right?

I just want to make sure before I twist 88 hard-to-reach
screws!

Paul, dumb question here:

Have you checked lost motion on this action yet?

Yes, as I've mentioned previously, I started regulating lost motion, but stopped when I realized I skipped setting the hammer stroke. I'd rather only do step #13 once, as it's quite tedious to turn the lifter wire screws on all 88 keys.

I was taught to adjust lost motion first, because it has an effect on so much else of what goes on in the action.

That could be part of your repetition problem.

I'm sure it is, because it's the middle keys that
have the most lost motion. My trills should certainly
be faster after I tighten those up.

So I should go ahead and do that step first, right?

And once again, a hammer letoff of 1/8" from the strings, and a hammer check of 5/8" from the strings are the right numbers, for a spinet too, right?

I just want to be sure these numbers are right, before I start bending backcheck wires, and turning hard-to-reach
screws...

Published specs:

36" piano with Pratt Read action: 1-5/8" plus or minus 1/16"
All others with Pratt Read action: 1-3/4" plus or minus 1/16"

Yes, IMO, do that step first.

Those numbers for letoff and hammer check are close enough for spinet work.

Paul,

I haven't finished all my work on my Kimball, but I suspect the blow (that is the correct term) will be about 1 3/4" But I really don't care, you cannot tell what the blow is without a ruler, but you can tell if you have too much after touch, not enough after touch, etc. by the feel of the key. Start with sufficient key travel, yes you may have to regulate lost motion more than once, this is why we start with samples to at least minimize the amount of error. Checking is the last thing to worry about because it can be impacted by everything else you are doing. Even more important to a consistent touch is damper timing... but that is a whole other set of problems.

Learning to regulate is a lot like tuning. You have to learn how each step impacts already completed steps and future steps. Just like you should be able to start your temperament on any note, you should be able to jump into a regulation process at any step along the way and understand the impact on all other steps. And sometimes a major pitch change can necessitate an additional pass, it can take a couple rounds through the regulation to really refine things. So don't be afraid of having to repeat a step, it is just part of the learning process.

Let me tell you about the first time I leveled a set of keys on my own... several hours later it was still a mess.

Ok, with such a complex mechanism, it would not
surprise me to find that it's not just a linear
process, but an iterative one.

Ok, after completing lost motion adjustments, I have
to say it's a huge difference. Much more firm, and
feels "harder" to play. But in actually, the "easiness"
of before the adjustment was just the perception of the
looseness of the keys, which is deceptive because you
aren't actually making the hammer move when it's loose.
And trills are tighter and faster, or course.

So far, it's been wonderful making these adjustments for the first time, after decades of being a player only. I feel
even closer to the instrument now.

Not yet done with let-off and checking, but will let you
all know....

With verticals, especially lower-end ones, I find lost motion to be the single biggest factor affecting playability.

Ok, I would say for this spinet, that 1/8"
for the letoff is a bit too small.

1/4" is probably more appropriate, especially in the
bass notes, as some of the hammers wouldn't letoff
at all sometimes.

The specification is 1/8" plus or minus 1/32".

If regulating properly and the action components are still within tolerance for nominal adjustment (ie not worn out)... I agree with BDB.

I would disagree with that spec for this particular
spinet. I saw one spec making the let-off larger
in the bass, and smaller in the treble keys, and I would
agree with that. But 1/4" overall let-off would be good for this piano.

Although perhaps I should sprinkle some graphite on the
jack heads before I decide on this.

There are better substances than graphite. Don't forget that a longer let off distance will affect softer dynamics as well as repetition.

You can disagree all you like, but that is what is in Kimball's specification.