Following are a few words on bedding we exchange with Ric, I am not sure of what goes on really, but we may probably consider that, depending of the way the weight of the action is distribued, the flexibility of the components, and the accoustical response 'so called circle of tone in some brands', we have to have a more firm contact on the screws for some pianos, and less for others. Rigid keyframes have to be bedded wery tightly all around their perimeter, while may be flexible or softer ones may can have more weight driven towards their center with the bedding to give a better energy transmission. Yamahas being heavier around the hammer rail, and having the bedding screws far from this point, are may be asking for more pressure on the screws to"balance "the weight of the action more efficiently. Remember that under heavy playing everything is under flexion, and there is a somewhat long delay between the key bottoming and the move of the hammer hitting strings. And here is a little experiment for fun : if you make a little arch AlaSteinway under the flange screw (with an electric file) place on a grand (Renner or Yamaha kind), and put back the part in place, and compare the tone, you will have a more clear and audible tone, (and a screw that can't be screwed tight) I was told the process add some lenght to the hammer shank, that is possibly a part of the Steinway tone, even if the round part lay on a hard basement in that case - still looking for a way to screw the screw without having the center of the hammer moving (too much). Try it for yourself please, it is amazing and fun ! Best Regards. Isaac Isaac OLEG wrote: > Hello Richard, > > I believe Andre is out for a few days, he will certainly add his > comments. > > What I believe is that for any number of punching (assuming they are not excessive or too thin) , you can obtain a key height that is in the acceptable range (64mm for Yamaha, 66 for CF3, 64-65 for Steinways, etc). At the same time the so called 10 mm dip is checked, so we try to have enough pressure on the bedding, with almost 10 mm of dip, and approx the good key height at the same moment (sometime at the expense of tone if necessary :>(. > May be you should consider inserting a 0.5 mm paper punching at the key, so the dip will allow you to have a more high hammer line without the tails getting caught in the backchecks. >raising the balance on Yamahas have not a such large effect on the action stacks height as on Steinways, but the letoff get closer for sure. On Yamahas the bolts are checked while lifting the aluminum rail with 2 or 3 fingers, if you check by tapping near the regulating screws (Steinways procedure) you'll have a too light pressure. > > I'd say that only hardwood frames as Bechstein, Grotrian and such have to be regulated with the screws lightly touching the keybed - it is very accurately done with a dial gauge, inversed and installed on a small drilled wood block, then ASAP the distance between the keys and the underside of the wrest plank change, you see the needle moving, and then you can check with the tapping test - these are particularly difficult actions to have well bedded with only the tap test, as it taps only with a very even and light pressure. > > On Yamaha's and Steinways, you can (and may) play with the bedding screws very often, that gives also possibilities to "open" a little the tone in some part if the hammers are really too hard and you don't time to needle them. To the points I've seen some Steinways bedded only with the 2 extreme screws, all the remaining was very open and warm (but with a clear flex sensation) these lazy lousy techs sometime > .... > > best Regards, take care > > PS action stack screws are to be checked often and they add power when tight. do you know the normal procedure on yamahas(turning reverse clock for the right side and clockwise on the left side) > > Too bad I was really expecting a good key flex approach for some Yamahas ! > > Friendly wishes. > > PPS it took me 6 months or so to find a good "feel" for bedding, but once caught it is indeed very useful, and allow a lot of changes in a very few moments. The "tapping test is not a name that tells it, as it is more an impulse with some force, that you apply on the balance capsules, banging or tapping is unclearing what we hear, you can also apply the top of your hand under the pin block so you have enough force, while lifting the regulating screw or action rail with the other hand. > > More pressure on the center than on the outer ... > > Bests again > > saac OLEG > > Entretien et reparation de pianos. > > PianoTech > 17 rue de Choisy > 94400 VITRY sur SEINE > FRANCE > tel : 033 01 47 18 06 98 > fax : 033 01 47 18 06 90 > cell: 06 60 42 58 77 > > > -----Message d'origine----- > > De : Richard Brekne [mailto:Richard.Brekne@grieg.uib.no] > > Envoye : jeudi 22 mai 2003 22:43 > > A : oleg-i@wanadoo.fr; Pianotech > > Objet : Re: No Power Yamaha revisited > > > > > > > > > > Isaac OLEG wrote: > > > > > But, Richard, that is felt in the tone and in the key if > > the bedding > > > is not firm enough. > > > > Yes... I know this Issac... its what I have been > > questioning about for a > > while now. The problem was not the firmness in the bedding, > > but the fact > > that the glide bolts werent forcing the balance rail up high enough, > > evidently anyways. You refer to this as putting the action under > > compression I think, yet I find no exacting proceedure for > > setting this > > anywhere. > > > > > When playing hard the back of the frame tend to lift up, > > may be you > > > may check the holding of the rail there. > > > > I did all this many times... and it has been good tho the > > bedding was > > lower. > > > > > > > If too much pressure on the screws, the tone became more > > "woody" and > > > straight, the more power that you have is also coming > > from the letoff > > > which is nearer, but mostly (I believe) because the > > hammer center pin > > > is then higher, and if the hammers are less tall than > > originally this > > > correct the geometry of the hammer towards the strings a little. > > > > The increase in power did not come from any change in > > letoff. For the > > first.. there was no uniform change, the power increase > > more than likely > > came because the force that was put into the key is no > > longer getting > > dissipated in all the flexing that was going on. There may > > have been a > > slight change in blow distance, I didnt check because the > > increase in > > aftertouch needed paying attention to then and there, so I > > just lowered > > the line. But if so it was not very much. How much the > > hammer centers rose > > is another thing. On the C7 I have I can pay closer > > attention to that. I > > doubt tho that the slight change in hammer angle this would > > cause would > > account for this increase in power. > > > > That being said, the "feel" of the action under the differeing > > circumstances seems to conform nicely to your first > > sentence. If I screw > > them up to high I did get a woody character from the > > tone... I presumed > > this was because the action itself was contributing to the > > sound more. > > > > Another point was that I had to re-regulate back checks, > > and checking > > could not be so high as before. Forced me down to 15 mm > > from the strings. > > Any higher tho and the checks would hang on the tails on hard blows. > > > > > > > For what is worth, the point by point method as explained by Andre > > > works every time - but you are supposed to know what key > > height is the > > > norm for the model, it helps a lot to have an even ratio between > > > blacks and whites, and put the keys in their optimum position for > > > regulation. > > > > > > > Thats the real trick tho isnt it.... ? I mean key height is suddenly > > dependant on two things... balance pin punchings, and > > balance rail height. > > How are you to determine one without knowing the other ? > > And like I say, I > > have not run into any specifics about setting balance rail height > > before... only bedding proceedures that state the glide > > bolts need only > > make firm (all of them) contact with the keybed. > > > > I would really appreciate seeing Andres point by point on > > this again... I > > remember a post he wrote about glide bolts not so long > > ago.. but I dont > > remember this being a point by point proceedure. If you > > have that please > > post it :) > > > > > > > > Thanks for the feedback. > > > > > > BTW I bed the keybed of a C6 today, with the regulating > > screws a good > > > 2-3 mm lower, the key height was 64.5 mm, allowing for 10 mm dip, > > > measured with the nice brown 9.95 mm dip block from Yamaha. > > > > > > The Yamaha (-French) explanation about the use of this > > tool (and why > > > it is not really exactly 10 mm) is that it is easier to > > feel the block > > > while it is a little lower than the adjacent keys, we aim > > for the same > > > sensation than the little play in the jack's windows. I like these > > > over simplified approaches ! > > > > > > Best greetings > > > > > > Isaac OLEG > > > > > > Entretien et reparation de pianos. > > > > > > PianoTech > > > 17 rue de Choisy > > > 94400 VITRY sur SEINE > > > FRANCE > > > tel : 033 01 47 18 06 98 > > > fax : 033 01 47 18 06 90 > > > cell: 06 60 42 58 77 > > > > > > > -----Message d'origine----- > > > > De : pianotech-bounces@ptg.org > > > > [mailto:pianotech-bounces@ptg.org]De la > > > > part de Richard Brekne > > > > Envoye : jeudi 22 mai 2003 18:12 > > > > A : Pianotech > > > > Objet : Re: No Power Yamaha revisited > > > > > > > > > > > > Ok guys and gals... > > > > > > > > I gots to eat crow here... I think anyways. As it turns > > > > out I managed > > > > to finnally solve the hammers bouncing all over the > > place thing by > > > > turning up all the bed screws so that the key frame was > > > > solidly bedded > > > > with the actuall wood of the balance rail a full 2 mm > > > > elevated over the > > > > key bed. Huge increase in power, but this also caused > > an increase in > > > > keydip to 10.5 mm (!) and forced a drop in blow to just > > above the > > > > cushions... perhaps the shanks are about 2-3 mm off. However.... > > > > absolutly no bouncing of neighboring hammers any more, and > > > > that feeling > > > > of loosing power is gone. > > > > > > > > What I dont get is why the Balance Rail needs to be > > > > elevated so much. > > > > And how are we supposed to determine the proper balance > > > > rail height to > > > > begin with ? I was always told that glide bolts need to > > just make > > > > contact with the key bed... not to lift the whole darn > > > > middle of the key > > > > frame up. > > > > > > > > Explainations please ? > > > > > > > > RicB > > > > > > > > -- > > > > Richard Brekne > > > > RPT, N.P.T.F. > > > > UiB, Bergen, Norway > > > > mailto:rbrekne@broadpark.no > > > > http://home.broadpark.no/~rbrekne/ricmain.html > > > > http://www.hf.uib.no/grieg/personer/cv_RB.html > > > > > > > > > > > > _______________________________________________ > > > > pianotech list info: > > https://www.moypiano.com/resources/#archives > > > > > > > > > > _______________________________________________ > > > pianotech list info: https://www.moypiano.com/resources/#archives > > > > -- > > Richard Brekne > > RPT, N.P.T.F. > > UiB, Bergen, Norway > > mailto:rbrekne@broadpark.no > > http://home.broadpark.no/~rbrekne/ricmain.html > > http://www.hf.uib.no/grieg/personer/cv_RB.html > > > > > > -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html http://www.hf.uib.no/grieg/personer/cv_RB.html
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