Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Downweight difference Sharps Vs Naturals

Should there be any? Assuming measurements are taken essentially near the front edge of each the ebonies and the ivories. I ask because, in all the measurements I've taken on three different pianos, I've noticed that the sharps are often a couple of grams heavier. I realize what could mechanically cause this. I really just want confirmation that it is, or isn't, supposed to be that way.

TIA,
Chris

I have no idea actually and can not make a pofessional comment on this but...If you think about it mechanically it is going to take more weight to move the sharps than the naturals. I am not an engineer but thinking along those lines the naturals have a longer moment in the arm than the sharps do since they are longer than the sharps. I know the balance rail pins are stagered for this so if it is possible why don't you do a little experiment to see. Can you use the same weight amount at the exact same location on a natural as you use it on the sharp?

I would be curious to see if my little theory will hold water or not. Then again I could just be smokin' some of that funky stuff :p

The gram weights should be positioned over the front rail pin. Key weights would compensate for variance in touch weight between keys. Mass production probably ignores this step in many pianos built today.

..Bob, was that your answer. Do you mean key weights would, or *should*, fully compensate for variations accross keys?

Anyone else with a yes, or no. It sounds like there shouldn't be variations, if what I'm hearing is correct, but I was kind of hoping for a more solid response.

I haven't done a final regulation with the existing hammers and shanks. The springs in the back, that not everybody is familiar with, are fairly easy to regulate to vary DW/UW. The fine tuning stuff won't happen until new hammers go on.

One observation I have made is how heavy the action feels from the bass break on down, even though the DW's have been reduced from high 60's to just below 55 grams. In my novice level, I didn't want to learn how to reweigh, but the three leads found in the keys found down there keep things feeling heavy despite the downweight. On a scale, the keys themselves go up in weight from the high treble down to the bass break, where they jump suddenly up by 5 grams. It seems like a lot in tactile sensation, when you're going from 24 to 29.

Chris

Chris,

I am definitely not a piano technician, but I am very interested in your question. I believe that the key/wippen/hammer assemblies are the same for black keys as they are for whites. If that is in fact the case, then the force should definitely be greater on the black keys due to their shorter moment arm (I think they all rotate about same axis; balance pin?). I wish some techs here would talk a little more about this.

Rick,

Always glad to see others who are curious. I wish we did see more tech discussion. Its kind enough of those who are here to help out and answer our own questions. The PTG archieves are still another great way to go.

The moment arm (I am not that great exressing things that way) is actually coming from its own balance point, which for the sake of analysis, is about 1 inch aft of the same point for the naturals. It leaves unanswered whether there is any strategy to setting sharps up differently, or not. Perhaps sneaking into a high end shop with some weights is in order

Chris

Chris said:

Wow, I didn't know this. Is this true for all pianos do you think? And if so, what about the capstan(?)(where force is exerted to the jack)? Are they still in the same place black to white?

Yes, where the balance rail has independent placement for sharps further back than that for naturals, the capstan will likely wind up in the same place, and be in a straight line from bass to treble. I can't speak for all pianos, but my two and actions I've seen, always do this. The principal is in providing the same amount of leverage to the tip of the capstan. If you measure where you strike a sharp diagonally to the base of the aforementioned (further back) balance rail point and contrast that distance with the distance to the tip of the capstan, you should get approximately a 2-to-1 ratio. For naturals, both distances rise, but the ratio should stay the same.

An interesting note about Steinway's is that the capstan line, thoughout their history, has been found to vary in the ratio it produces from 1.8 to almost 2.2 (usually expressed as the reciprocal on ptg.org, if you search 'key ratio').

Your question raises an interesting point that is helping me understand why sharp/natural downweight can vary with uniformity. If a capstan line changes, say further out within the range of 1.8-2.2, the sharps are going to get heavier faster than the naturals, since their key ratio is made up of smaller distances. I think Jon Page pointed that out to me a long time ago and I since forgot it. Its a relevant QC issue if you translate these distances into downweights.

Thanks,
Chris