Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Regulating the action on and old Kaps concert grand

Hello all,

I'm trying to fix up and old Kaps concert grand I bought recently. I'm trying to fix the action, and am not a professional, just a mediocre pianist I'm afraid. I would get a tech in to have a look but I only know of one (questionably) good one here in Uruguay, and he's not free until March.

Anyway I've got the keys more or less square, but I have a problem with the hammers. I've aligned them up ok at the beginning then noticed they were too far from the strings, so I aligned them again to be 4.6 mm from the strings, however I've just read some where that they should also be just hovering over the hammer rests, which they are not anymore.

Its an old rocker capstan system so its a bit of a pain to regulate, but not impossible.

The hammers hovering just over the rests result in a distance from the string of about 5.6 cm. The hammers at a distance of 4.6 cm from the strings hover about 1 cm over the rests. Maybe this piano was designed to have the hammers 5.6 cm from the strings?

Here's some pictures of the action:
http://www.grassgames.com/other/piano/Kaps/KapsAction.jpg
http://www.grassgames.com/other/piano/Kaps/KapsActionBottom.jpg

And some pictures of the hammers - I lowered one of the hammers to be just hovering over the rests - the others are at 4.6mm from the strings:

http://www.grassgames.com/other/piano/Kaps/KapsHammersHeightFront.jpg
http://www.grassgames.com/other/piano/Kaps/KapsHammersHeightSide.jpg

Thanks for reading.

Hi,

I appreciate your position. Because of a lack of qualified technicians, you are forced to try to figure out things on your own.

If you like, I may be able to help you over Skype. Send me a PM.

I teach the "Regulation Triangle" in my course. It is my own teaching tool. It is an easy way to visualize how all the elements of the action work together.

Basically, the triangle is let-off, hammer distance, and key dip.

Each one has an ideal setting, and a "pro" side, that is, the side of the ideal setting, or standard specification, that improves the action.

For hammer distance, if you could get more than the specified amount, you would gain in power, pro side.

For let-off, if you could get closer, you would gain in softness and response, pro side.

For key dip, if you could have less, you would gain in speed, pro side.

The trick is, once the action is regulated properly, i.e. you have proper jack movement and after touch, the only way to get more of any one of the triangle elements, (more power, more response, or more speed) is to sacrifice one or both of the others.

Why am I telling you all this? Because distance above the hammer rest rail is not one of these elements. The only criteria for the hammer rest rail, is that the hammers do not rest on it. (Yes, I know, why do they call it that then.) Anyway, it is there, IMHO, so on hard blows, the hammer shank, or some other part of the action, doesn't break.

If you like, there is usually an easy adjustment to raise the hammer rest rail. Just keep it from touching the hammer shanks. I would say 5 - 6 mm.

Good luck.

This piano does not have a hammer rest rail, it has individual hammer rest cushions which are not adjustable.

With only a few pictures to go on I will take a stab at this one:

This is a very old piano, probably 1890s. The hammers have been replaced, relatively recently. The hammer bore length is much shorter than the originals, and this causes the problems that you see. Unfortunately, this is probably only the beginning of the problems anyone will encounter when they begin to try to regulate the piano. It may not be possible to properly regulate it at all. The hammers need to come off and new hammers, properly dimensioned for the piano, need to be fitted. Sorry for the bad news.

I would start by trying to regulate one or two notes. See if you can get them to work reasonably well. If you can, you should be able to do the rest to match.

The shank rests are only to keep the tails of the hammers from hitting the flanges and screws. The hammer shanks should rest above them, but it does little harm for them to be way below the shanks when they are at rest.

If it is necessary to increase the hammer bore, you could remove the existing ones, plug the holes and rebore them, although that is not simple. I only suggest it because it may be difficult to get supplies in your country.

Great replies - thanks folks, and I appreciate the Skype offer Mark, I'll keep it in mind.

However I managed to make some progress in regulation in the last few hours and its is starting to feel a lot better. Its still a long way from perfect though.



Its old alright - the serial number is 10600 which would make it 1885 going by this post from someone called Matt back in 2008 at piano-tuners.org:



It appears to be originally brown (mahogany?) and painted over black at some stage but looks good none the less. Its 8.5' long and has 90 keys:

http://www.grassgames.com/other/piano/Kaps/KapsPianoTop.jpg

The hammers have been replaced also - I filed them a bit myself - they were like this when we got it (I'm not happy at all at the cut one on the left - apparently it was needed to "fit it in" but that's bs):

http://www.grassgames.com/other/piano/Kaps/KapsHammers.jpg

I'll measure the hammer bore length tomorrow and check the angle that they hit the strings at, and do some more regulation. Is is ok to assume then that to leave the the hammers 1 cm above the rests won't cause problems later on?

I'm Irish by the way just living in Uruguay for the moment.

Thanks again for the information people.

The distance of the shanks above the rest felts when the blow is set to 45 mm is not the problem - it is indicative of a larger problem.

Pictures: double overstrung - I love it!
Kaps made some nice grands, but I have never seen one that size. 90 keys? Does it go down to a low G??

I would say "good luck", but since you are Irish that is redundant....

Yes, you can see the low G in the action photos in the first post.

The hammer "rest" cushion is usually 3-6 mm from the shank, and helps repetition at FFF, also.

old pianos had sometime extra tall hammers, some of them even not available today. plug and bore is an option for someone with correct equipment, it should be less costly to order a set bored and having the good dimension, from Abel for instance.

In the last of the 4 pictures the shank is yet a little too high from the cushion may be 2 mm.

It is seen that the bore is too short, the drop screw are raised to the max.

I doubt the piano could have a nice touch with the keys being so long in the treble, there must be quiete some flex, I would try to reinforce them if it is not done yet

I suppose the hammers used where standard bored

Very interesting leading of the hammer rail (is it lead ?) for mass or resonance reasons

You may wish to find a blow of compressed air, to clean the piano.

New hammers of the good dimension can be ordered, even on line, but you need to measure a few dimensions.

SHanks can be changed too.

If you get the parts, possibly the tech could install them for you , it would take a week at the max.

You even have no option to raise the stack, because of the transmission (zero friction transmission, but the keys tend to bounce, hence the importance of the shank to cushion relation)

see above , you will have a bump in the fingers as the shanks are not stopped. I would use 56 mm hammer stroke if they impact the strings at a correct angle .

but due to the kind of work done, I would be cautious, and try to measure the A 49 lenght, then the strike point, and see if the hammer strike at 1/8 , 1/9 or where it goes exactly.
too small hammers may impact with too much high pitched noises (may be because some initial wave goes toward the capo more than in direction of the bridge, so the initial tone is containing more capo noises and high picthes than wanted, less energy allowed for the fundamental too.

But the strike line is really what matters the most in mediums and treble, particularely.
When the hammers trike near a node (1/7 1/8 1/9)a minimal move from the strike place produce maximum tone change

Kaps can be nice old German pianos, with strange actions for what I have seen

You can try to raise the front of the stack 1 or 2 mm if it helps the hammer orientation toward the strings, (it also will move the strike line) more is probably not possible due to the link between keys and action

P.S "regulation" mean first cleaning all dust, spacing all parts and tightening all screw (plus action center checking)

The look must be neat and clean, not awful like there

ANd you just need a screwdriver to do much of that job

You have a problem with the jack not being well centered under the knuckle, unless this is the picture

That could mean that the spread have moved (the distance between hammer and whippen rail have enlarged)

This only may suffice to give you too large letoff and too soon drop

Thanks for all the replies Olek. I'm not a tech by the way, so I don't understand what you mean by A49 length, and I'm not sure how the measure the strike point, or what you mean by 1/7, 1/8 and 1/9.

Also I don't have access to an air compressor at the moment, but I'll ask some neighbours. I'm in rural Uruguay - try to imagine rural France (or Ireland for that matter) circa 1950, but with internet and mobile phones and you'll get the idea. I can order parts online, but they will take a month to get here, and anything that costs more than $US200 and you have possibly 100% import tax to pay. The joys of living in South America! Also no techs or local parts shops.

There's another problem now - with the hammers at 4.6 from the strings they just about fit into the box, and the drop screws need to be nearly at full height (or no height as it may be), and they also just about fit it.

I adjusted the let off and drop for the bass strings also and the drop screws actually scratched the roof of the box - I didn't notice in time when I was putting the action back in. I didn't change the height of the bass strings - they are currently at 6.5 cm from the strings.

See the pic here:
http://www.grassgames.com/other/piano/Kaps/HammerHeightProblem.jpg

When parts do not fit, you need to do the best that you can. Go back to what I said: Start with a few notes, and get them to work. Forget about measurements or aiming for the ideal response. Get them to work, then match the rest of the notes to them. You may need less hammer blow and more let-off and drop than desirable, but that is better than a piano that does not work at all.

Ok will do - Its getting there anyway - bit by bit it'll get better I hope.

I will post you privately about what is possible.