Kaps Grand Piano Action

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AidanMck
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Kaps Grand Piano Action

Post by AidanMck » 06 Feb 2013, 21:03

Hello there all,

I've just got myself a very old Kaps concert grand piano (1920 I think, but can't find the serial number), and I want to have a bash at fixing up the action myself if I can. I've already tuned it ok, but the action feels pretty bad. Some of the keys are stiff, others rattle, etc.

The first thing I wanted to try to do was to align the hammers, but all searches on the net recommend adjusting the Capstan screw, which as far as I can tell this piano does not have, so I'm stumped before I can even begin.

Here's a picture of the action:
KapsAction.jpg
And some of the hammers:
KapsHammers.jpg
And here's the bit where the keys kit the wippen - I (a super novice) can't see any Capstan screw:
KapsActionBottom.jpg
(continued below)

AidanMck
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Re: Kaps Grand Piano Action

Post by AidanMck » 07 Feb 2013, 01:07

(continued from above)

And some more close ups thay may be of interest:
KapsActionBackView.jpg
KapsActionCloseUp1.jpg
KapsActionCloseUp2.jpg
Here's some hammers when some keys are pressed:
KapsActionKeysPressedFull.jpg
And a side view with the hammers removed:
KapsActionSideView.jpg
I'd like to get the action reasonably good if possible. I'm working (with help from the missus) on fixing some of the felt inside some of the rattley keys at the moment, but would like to get those hammers aligned asap.

I know the best thing would be to call someone, and I did, but the only good one I know of in the country where we are at the moment, Uruguay, is on holidays until March, and I've no idea how good he really is, so any help would be greatly appreciated.

Cheers and thanks for reading,
Aidan.

lluiscl
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Re: Kaps Grand Piano Action

Post by lluiscl » 07 Feb 2013, 15:44

Hi. This old action uses a rocked system to connect the key to the whippen (no capstan here), so you'll need an special offset screwdriver to regulate their two screws, which at the end control the height of the hammers.

AidanMck
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Re: Kaps Grand Piano Action

Post by AidanMck » 07 Feb 2013, 18:43

Thanks lluiscl, yes apparently otherwise known as "rocker capstans" - here's a nice picture of the workings taken from this page:
http://my.opera.com/BerndAB/albums/show.dml?id=5729542
RockerCapstanMechanism.jpg
I've started aligning the hammers today after sanding them this morning. Here are some at rest:
SomeHammersAtRest.jpg
The problem is when pressed down slowly they look like this:
SomeHammersHalfPressed.jpg
And when pressed down fully they appear like this:
SomeHammersFullyPressed.jpg
There appear to be three main things I need to adjust - the rocker screws, the letoff adjusting screw and the drop screw (at least that's what I think they are):
Adjusters.jpg
I'm making some progress by trial and error, but I'm not really sure what I'm doing or why, or what the relationship between them is exactly - e.g. the drop screw only seems to have an effect at certain positions of the other two, and I'm not sure completely what the letoff adjusting screw is doing, and how it affects the half way position or fully down position or both.

Some info would save me hours/days of time I'm sure.

Withindale
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Re: Kaps Grand Piano Action

Post by Withindale » 07 Feb 2013, 22:05

See Understanding Regulation in this forum - it works.

AidanMck
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Re: Kaps Grand Piano Action

Post by AidanMck » 07 Feb 2013, 23:50

Ok I've read that - interesting.

What part/parts are you referring to:

1) Breaking off the hammer heads, shortening the shanks, and re-gluing them
2) Adjusting the tension of the repartition spring
3) Reading "Complete Grand Regulation" by Roger Jolly
4) Reading "Piano servicing..." by Arthur A. Reblitz
5) Reading Kawai's Grand Piano Regulation manual
6) Something else I missed?

I'm not keen on number 1, that's for sure, and Reblitz's book is a bit heavy.

Withindale
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Re: Kaps Grand Piano Action

Post by Withindale » 08 Feb 2013, 18:53

Not 1 and don't do 2 unless you have to. Download 3 and 5 and see what you can make of them. I read most of 3 and then got the feel of it for myself. The other thing to do is look at Ed Foote's posts on various aspects of regulation, posted before Christmas last year on Pianoworld, and then follow those threads. Barrie, Colin and others here will tell you the same things in less words.

I set set-/let-off by the blocking method and then set drop by comparing each key with its neighbours. These became quite fine adjustments. Aftertouch was the final thing. I had to go round the loop more than once to achieve a reasonable result. What I learnt is that you should start with key levelling and key dip. I postponed some of that as the keys will need rebushing in the near future and, as a result, the hammer line is not quite what it should be.

AidanMck
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Re: Kaps Grand Piano Action

Post by AidanMck » 09 Feb 2013, 19:40

Thanks again - I couldn't find those posts you mentioned, but found hundreds of others, and decided to post some updates over there instead, as there seems to be more action over there (no disrespect to this place, its great too, and no pun intended either).

The Kawai manual is great for a novice - Mr. Jolly's may be too, but it badly needs pictures, its hard to understand the prose when you are not familiar with the process.

Cheers,
Aidan.

Withindale
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Re: Kaps Grand Piano Action

Post by Withindale » 09 Feb 2013, 20:45

Roger Jolly's original article may have had pictures but you can use your action, or say http://www.piano.christophersmit.com/playingMech.html, instead.

Technicians spend ages learning to regulate grand pianos so a little bit of homework understanding how things work is warranted!

Google for "Foote aftertouch" or "Foote let-off".

Good luck.

AidanMck
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Re: Kaps Grand Piano Action

Post by AidanMck » 09 Feb 2013, 21:09

Ok found it. Before I get to that though I have a problem.

The hammers are aligned, but if I place them hovering just over the rests this result in a distance from the string of about 5.6 cm. If the hammers at a distance of the recommended 4.6 cm from the strings then they will hover about 1 cm over the rests. Maybe this piano was designed to have the hammers 5.6 cm from the strings?

Here are pictures of the hammers - I lowered one of the hammers to be just hovering over the rests so you can see the problem - the others are at 4.6mm from the strings:
KapsHammersHeightFront.jpg
KapsHammersHeightSide.jpg
Thanks for all the help.

Withindale
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Re: Kaps Grand Piano Action

Post by Withindale » 09 Feb 2013, 22:03

The full answer to your question is for the experts, but as I understand it the hammers should line up above the rests. The hammer actually rests (indirectly) on the capstan, and you adjust that so that the jack travels far enough to have just moved away from the knuckle as it rebounds. The key hits the cushion at the same time. Have a look at Christopher Smit's animation.
Last edited by Withindale on 10 Feb 2013, 10:11, edited 1 time in total.

AidanMck
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Re: Kaps Grand Piano Action

Post by AidanMck » 10 Feb 2013, 06:34

The animation helped loads, and that combined with the following videos got me going in the end:

http://www.youtube.com/watch?v=M-bs-dKnooo
http://www.youtube.com/watch?v=01DBtig_Fgw
http://www.youtube.com/watch?v=HrhGfwB_420

I managed to do some proper regulation and boy was I chuffed :D. I did the middle and treble strings and tried them out and things feel a lot better now than they did, far from perfect, but defo. getting there.

I'll leave the hammers hanging in the air for now and see how it goes, I can always change things around later on.

Thanks for the help!

rocklandpiano
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Re: Kaps Grand Piano Action

Post by rocklandpiano » 21 Feb 2013, 10:32

Unlike your car, computer or digital piano, a quality real piano will be as good (and possibly better, as most new hammers take time to settle) in 10 years time as it is today, based on normal 1 hour’s use per day. After 20 years it will need light adjustment and toning of the hammers by a qualified tuner. In 50 years it will probably need two or three days’ reconditioning and possibly new hammers and bass strings. During all this time it is highly unlikely to go wrong at all. Older pianos sometimes carried lifetime guarantees! There are over 3 million pianos in the UK.

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