Unusual piano and unusual action

[Stéphane Collin]

Hi Calin.

Nice piece you got there.  About the year of construction and about the maker, I don't know.  But I can give you my thoughts about the regulation (wich is pain, as in all older models).  For this, ask maybe also to John Delacour, who has seen lots of things.

1. Begin with making perfect key bushing job (see the site of Renner USA technician zone for neat procedure).  Even out the friction all over the compass.  You do this by removing the stack and measuring with keys only the downweight (DW) and the upweight (UW).  Friction (F) is given by the formula : F = (DW - UW) / 2.  At this stage, friction values should be about 3 to 6 gram.  Make them consistent by easing the bushings (front and balance) who are too tight.  Don't go that far, tho,  that the keys start wobbling.  Important thing is that all keys are even, within 1 gram difference.
2. Set the key depth to 10 mm (which is a good standard).  Don't forget to compress your front rail punchings before using them (whether knocking them with a hammer, or letting them overnight under some kind of pressure).
3. Set the hammer rest rail (properly refurbished, ask me how if you don't know) to the correct hight.  This is, for 10 mm key travel, the hammer must do the travel from rest to string, no more, not less, and the feel must be agreable (enough aftertouch).  Hammer rest position should be somewhere about 47 mm from the strings (could be less, probably not more).  Funny : this should be tapered, since bass strings are thicker than high trebble strings.  By the way, check if the hammers hit the strings at a 90 ° angle.  If not, ask me for red plan emergency procedure.
4. Check all the jack center pins.  These should be quite loose : as in a modern action, the jack should be able to move under his own weight (to minimise frictions here).
5. Check / replace the leather at the nose of the hammer.  It is important to use here the very best quality leather, in this case, the leather which will give the less friction when the jack is rubbing against it.  When chosing the direction of the "grain" of the leather, you should favor the return movement of the jack.  In this case, the "hairs" of the soft leather should be directed from hammer side to key side.  Don't forget to lube with teflon powder on the leather, and burnished graffite on the top of the jack.
6. Regulate the rocker on the key so there is nearly no lost motion, thus no gap between the jack and the nose.  This is important as too great a gap will cause disagreable touch feel and no gap at all will make repetition slower.  I do this regulation by feeling with my finger the "quality" of the micro gap between jack and nose, while tapping slightly on the key.  You could do it by testing if in rest position the jack does rub against the nose (this should be avoided).
7. Regulate the rocker spring.  The purpose of this spring is (I think) to maintain the jack in good position before set off (avoiding premature set off of the jack).  So you should regulate it just strong enough so the jack stays in good position before set off.  I see no reason to regulate this spring stronger than this.
8. Regulate the correct set off by turning the set off button.  With this kind of action, you can drive the hammer very close to the string.  I regulate this letting the hammer block against the string, and then reducing the set off screw progressively until I can't feel any blocking of the hammer anymore against the string.
9. Regulate the extra shoe spring.  What I would here keep in mind is that this shoe should not interfere with the set off process, so the player doesn't feel any extra friction just before set off.  So this spring as strong as possible, just before it does interfere with set off process.  Anyway, you won't get miracle repetition with this thingee.
10. Regulate the key stop rail so the keys won't wobble on a forte stroke.
11. Even out the downweight values with the stack on, by regulating the screw on the hammer centers.  You should achieve something like 50 g downweight, without interaction of the dampers.
12. Regulate the checkers so the hammers check as close as possible to the strings.
13. Check the alignment of the hammers to the strings (correct by burning the hammer shanks) and the horizontal evenness of the strings.
14. When all this is done, voice to your taste.

Regards,

Stéphane Collin.

----- Original Message ----- 
From: "Calin Tantareanu" <dnu@fx.ro>
To: <pianotech@ptg.org>
Sent: Tuesday, July 16, 2002 3:29 PM
Subject: Unusual piano and unusual action


| Hello!
| 
| I have recently bougth a Schweighofer grand made in Vienna around 1870 (date
| is not certain, serial number is 3326). it has parallel strings and some
| metal bars and a hitch pin plate, no cast iron plate.
| The most unusual thing about this piano is it's action, which is not
| Viennese, as I would have expected from a piano made in Vienna long ago. It
| has a type of English action with a device that works like the repetition
| lever in a modern action.
| you can see pictures of it here:
| http://calintantareanu.tripod.com/piano/schweighofer/index.htm
| Have you seen this kind of action before? What's the name of it?
| I would also need some info regarding regulation. Any special procedures?
| I would also like to hear more about the history of this piano maker, if
| anybody knows.
| 
| Many thanks,
| 
| 
| Calin Tantareanu
| ----------------------------------------------------
| http://calintantareanu.tripod.com
| ----------------------------------------------------
| 
|