Like this (keys are light blues, the rectangle/parallelogram is the hidden part of the action, not to scale). Of course the limitation of this design is that the keys go "inward" besides that down, but that can be probably made negligible?
Do you see any other flaws here?
I like finite length pivot, because by playing closer to the fallboard you can make the sound more soft (being slightly harder to press). I think there is a video (posted somewhere in this forum) of a pianist that did fast repetitions moving continuosly the fingers closer and farther from the fallboard to make variations in the sound timbre.
magicpiano I like finite length pivot, because by playing closer to the fallboard you can make the sound more soft (being slightly harder to press)
That's a good point even if arguably a good pianist should be in control regardless of playing point. And it goes contrary to PW wisdom of "mine is longer than yours" 🤣 so perhaps on PC as we age which should aim for a shorter or perhaps "optimal" length? But I digress…
Let's instead go back to my technical question about the parallelogram design. Do folks think it will work as expected for piano? Any obvious-to-you flaw like @Ralphiano did on the other one I posted earlier?
That is an interesting approach. It is similar to the parallelogram already in widespread use in bicycle rear derailleurs. But, they differ in that the derailleur receives force applied directly to one of the three moving sides of the parallelogram (one side is fixed to the bike frame). So, the derailleur force is applied very close to the critical pivot connecting one of the moving sides to the fixed side. On the other hand, when used as a piano key, the force would be applied to the key at a great distance from that critical pivot point. What effect these differences would have is another discussion.
I would anticipate that a main weakness would be the necessity for four pivots, one at each corner of the parallelogram. These corner pivots are the main point of destructive wear in a bicycle derailleur. As they wear, the parallelogram can begin to operate out-of-plane as the forces applied to the initial side can move the next, subsequent side in a twisting or direction different from its originally intendeded direction.
Though pivot wear is similarly a factor in plastic piano actions, it is not a factor in an acoustic piano that uses a balance rail instead of a pivot.
Another weakness of the parallelogram would be the necessity for a spring or other unnatural force to return the key after is it released.
If available space was not an issue, this could perhaps be mitigated by connecting the parallelogram to the piano at the midpoints of the horizontal sides of the parallelogram, and then adding appropriate counterweight to the side of the parallelogram that is exactly opposite the side to which the key is attached. It seems like this could introduce a more 'natural' feeling resistance force to the key stroke.
I'm out of time and have to run.
This parallelogram thing is interesting.
Make the mechanism from nylon. Then lube it with teflon. That'll take care of things.
Or … you could always resort to bacon grease. It slickens the path, and it smells like Sunday breakfast. 😆
Ok, so I'm thinking of this approach for a (slightly) different kind of application (still hybrid piano action). Sounds promising. I'll leave that story for another day, so let me get back to the common one.
Yes, in this case too, one side of the parallelogram is fixed somewhere on the structure of the instrument (and can be of different proportions compared to how I quickly drew it). The out-of-plane movements should be easy to take under control with the front rail key pin (like in a regular acoustic action), of which there could be even a second one in the back of the key. The wearing of the pivot points should not be a big concern, since there are similar ones on each flange for whippen and for hammer shank, and wear is not a huge problem. However there are two of them in an acoustic piano and they are considered an important source of friction which may become too much. So having four might be a problem. Using nylon and/or teflon (rather than wood/cloth) as @MacMacMac suggested could help a lot, and it's certainly something to explore, but that may require very tight tolerance to get it right or at least that is my understanding from the reading the technician's literature on the topic (mostly but not only regarding WNG).
Regarding the weight in the back, if there is lots of room one could just do the regular seesaw balance rail. The purpose of this is to make it less deep. You can still add a counterweight in the back with a very short leverage, but that will need each weight to be quite heavy, which is also not desirable. Alternatively, one could design a simple seesaw mechanism (or similar other folded action thing) and put it under the key. That way, there is plenty of design freedom to make it of the right touchweight without actually being very heavy (basically the only constrain is that it needs to be "out of the way" and not interfere with the parallelogram or the key itself.
I will start by saying that I could not follow all the mechanical details (and the engineering/physics principles...) of the proposed designs (I am too obtuse to understand the paralelogram), but I would like to raise a question. The piano key (flawed as it may be...) acts as a lever, and in that sense the force required to lift the whippen is smaller at the key tip than at the fallboard. By getting rid of the lever, will you transform the key in a long tip or in a long fallboard? My bet is that infinite length key will require fallboard force throughout the key. If so, what is the advantage?
vagfilm I will start by saying that I could not follow all the mechanical details
I'll see if I can build it with LEGO and post a video about it [1]. That'll make it obvious.
vagfilm By getting rid of the lever, will you transform the key in a long tip or in a long fallboard?
Well, I am not sure I understand your question, so let me rephrase it. Pardon me if I am answering something else, let me know if that is the case. You are asking "how heavy" this approach will make the touchweight: like it commonly is at the tip of the key, or like it commonly is at the fallboard?
The answer to the rephrased question is: it depends on how you build it. If you are using this thing as a digital piano key, you can either use a spring (and so it will be as heavy as the spring you put in) or you can use a seesaw below it (similar to a regular piano key) and have the actual key push the seesaw, but touching it in one point only. You can adjust the touchweight by choosing the place where it touches and the actual counterweight. Of course if you'd be using this in a regular piano (why? I don't know, you asked 😁) you can't change the "counterweight" (since there is none, and the whippen+hammer act as one), but you can still change the place of contact. I might need to add also this to the LEGO model or drawings.
🎶
[1] Does it need to be in youtube or could be an attachment here?
RIP I'll see if I can build it with LEGO and post a video about it
Hi. No need to patronize me. I was honest when I said that the details on the parallelogram approach and how it is similar to "bicycle rear derailleurs", is beyond me. I simply stated that I could not understand it, and since I did not ask for a clarification nor an explanation, no lego explanation is necessary for me. Keep up your adventure.
I think delvento probably mentioned the LEGO with the real intent of showing how it works, I doubt he meant being dismissive/patronizing, at least that’s how I interpreted from aside. Peace ✌🏻
Don't worry CG: all is well (but I cannot do the peace emoji... I don't understand derailleurs and I go as far as a few face emojis... 😁 )
CyberGene Peace
Is there a "Live long, and prosper!" emoji as well? 😁
So long as it's technical lego, it qualifies as a technical explanation.
QuasiUnaFantasia Is there a "Live long, and prosper!" emoji as well? 😁
The emojis are now so many that when I start picking up one, I usually search them typing keywords, and funnily enough for "prosper" the following emoji is shown, the one I also use for our "pianist" tag (for lack of anything closer to pianists): 🖖🏻 AFAIK, it's a Star Trek gesture.
Yup, that's the one! 😀
xooorx So long as it's technical lego, it qualifies as a technical explanation.
Indeed. And good thing that I did not say that I wanted to carve it by hand in walnut and put gold center pins 🤣
In any case, I wanted to do the LEGO for myself anyway, quickly recording it (sloppily) was a no brainer. Here it is:
It's in 3 parts (funny for a 20sec clip):
Actually, doing it in life has shown me one interesting feature!! It's always good to make prototypes, even LEGOs 😁 Suppose:
Then, by moving the seesaw back and forth (from pianist's view: left and right in the video) one could make this thing change the real touchweight of the keybed, not just the simulated one via the response of the audio! Wow! Isn't that amazing?
My bad... You were serious about the Lego explanation... Maybe it is a cultural thing, but in my neck of woods saying "Do you need to see it on Lego?" is something not nice to say...
vagfilm in my neck of woods saying "Do you need to see it on Lego?" is something not nice to say...
Ops, really sorry about that. I did not even thought it could be something bad! Just to learn the idiom, does it mean something like "you are stupid that don't understand this, it's so simple"? Weird about how different cultures have different ways to look at things and creating idioms.
vagfilm You were serious about the Lego explanation
Yes, I was serious and still am. I think using LEGO is a very nice thing to do for rapid pre-prototying (before moving to 3D printing for actual prototyping). As you might infer from the video, I need to buy more LEGO Technics kits, since I ran out of the "good" parts and had to steal some pink-house things from my daughter!
vagfilm My bad... You were serious about the Lego explanation... Maybe it is a cultural thing, but in my neck of woods saying "Do you need to see it on Lego?" is something not nice to say.
Here in the ‘states, this kind of expression/remark is used often enough in numerous variations that i no longer think of it as “bad” ….”not nice” or the like BUT it helps to know the context, such as here where there otherwise does not appear to be any bad blood/vibes evident 🙂 …. in a modern sense, “snarky” and “snippy” may be suitable characterizations ….. and maybe, folks from your neck of the woods are more formal/less vulgar.
Having spent years living various locales here in America, where each locale has its own repertoire of expressions to include a sub-section for snark, i first cut my teeth (translate: began growing some thicker skin ) during my first tour of the ‘burgh, circa 1978 …. where i first learned that this kind of not nice/bad/snark is generally known as “jag’in” ….. i was just jagin ….. as in “ just bustin your stones a bit” IE. a peculiar form of friendly endearment that to the uninitiated may look/sound like sarcasm as playful verbal warfare “ for cryin out loud drew, do you need me to draw you a picture of it?!” 😉 …. i’m just jagin but i think delvento was not.
Drew-r in Australia Lego is seen as evil satanic spawn because:
If someone buys your kid Lego as present without prior authorization then that's basically a declaration of war 😀
Perhaps similar sentiments exist in Portugal.
