Anyway, there's not much to report yet. I believe some of the backers should be getting theirs about now, but I have opted to wait for some design tweaks that will be part of the production model.

See also http://vaxmidi.com/vaxmidi-open-forum.html

I will report back in a couple of months when I get it!

[...](But maybe the VAX  are the only hammer actions without those rubber bubble contacts? True?)

yeah I think maybe the better claim to make would be the optical tracking vs the offset contact closure most keybeds use. Measuring a single point on the hammer at a high scan rate is a fundamentally different approach and certainly puts this system in rarified company (i.e. PNO scan) if not completely alone in the keyboard world.

Also, I think his assertion that every other keyboard senses the key velocity, rather than the hammer, is false - Kawai, for one, sense the hammer in at least some models, including my own very old MP9000 - it sensed the hammer shank, which is for practical purposes equivalent to sensing the hammer.

Yes,  indeed Kawai's RM3 and  Grand Feel (GF) are some of these models.
https://www.youtube.com/watch?v=AqQ4oaOCSXQ

Thank you.

(But maybe the VAX  are the only hammer actions without those rubber bubble contacts? True?)

For an overview of the hammer & key, start at 3:15.

Also, I think his assertion that every other keyboard senses the key velocity, rather than the hammer, is false - Kawai, for one, sense the hammer in at least some models, including my own very old MP9000 - it sensed the hammer shank, which is for practical purposes equivalent to sensing the hammer.

Greg.

Elastic force? Yuck - no thanks.

Greg.

well let me expand (unfortunate pun) on what I was getting at earlier: because what it comes down to (more unfortunate pun) is returning the hammer to it's resting state. In a piano, gravity pulls the hammers downward. It looks to me like VAXMIDI has a system that pulls the hammers back to rest with elastomeric tubing, if I'm seeing that correctly.

The end effect should be identical since we're talking about force acting on the hammer, not the key. If we start picking gnat's eyebrows, you could argue that gravitational pull (weight) would remain absolutely constant while spring force would increase the more the tube is stretched from rest, but I would guess the change would be negligible compared to that caused by the changing angle of the hammer relative to it's pulling force as it pivots. I doubt there is enough stretch to affect any meaningful change in the spring force in the first place.

My guess is that there would be no perceptible difference in the effect each type of hammer has on the lever through which you're manipulating it; the key, which remains free and unsprung (so it's not like a spring-return synth keybed). If the mechanics of the key/hammer interaction...the lever ratios, angles, friction, release point, etc. were the same, I would shocked if you could measure, let alone feel a difference.

So the question is...is the latter part done well? Does the mock hammer carry enough inertia to move and bounce similarly to that in an acoustic instrument? If so, I see no reason to dismiss the system based on the hammer-returning method. It is still a hammer action and should behave like one.

As for the black/white key rails...just looking at the extruded frame they're using for the 2-actave modules, I see only 2 rails; one for keys, and another for hammers. I assume this means all keys must pivot around the same axis.

Greg.

Greg.

I guess it can be derived [...]

Ok, I did some geometry.
Estimated width of a white key was 2.2 cm. From the relations of the "KEY STEEL" and "KEY A" I came to a length from fulcrum to front of the white key of 19.4 cm.

Cheers

PS: no warranty

Nice work..that seems believable, if on the shorter side. FWIW they cleaned up the spam and responded about black keys, saying an adjustment factor has been added (as percentage of white keys). I interpret this to mean a separate response curve for black keys, without changing the physical effort required.

And yes, it seems from what I can tell that he hammers return via elastic force rather than weight. I assume that, given similar hammer inertia and key/hammer lever interaction, there should be no difference in what you'd feel through the key tops between gravitational pull (weight) and elastic force.

I'll take "user serviceable" over a warranty any day. Now to see when they start shipping (sounds like their tester models are going out this week)

I guess it can be derived [...]

Ok, I did some geometry.
Estimated width of a white key was 2.2 cm. From the relations of the "KEY STEEL" and "KEY A" I came to a length from fulcrum to front of the white key of 19.4 cm.

Cheers

PS: no warranty

The "hammer" part of the key (if I understood the illustrations correctly) looks a little light to push the front of the key upward quickly from merely the force of its own weight falling, unless perhaps the front of the keys (where the keys are depressed by the fingers) have something to assist the process, like a spring.

I guess there is something "like a spring", see the Latex  Elastomers at  http://vaxmidi.com/vaxmidi-parts.html and the Key Action at http://vaxmidi.com/features.html .

At any rate, it is a very interesting project.

What is the fulcrum length, anybody know?

I guess it can be derived from http://vaxmidi.com/mechanical-parts.html

We know the width of a white key. There are drawings of white keys. And there is a drawing of the "KEY STEEL", which has a little hole where the fulcrum is.

Very nice project. I hope it will be a success once it is available.

aandrmusic wrote:

EDIT:
OK, it is now "later".
The octave_of_keys model doesn't help with trying to find fulcrum length, it confirms that the key width is 6.5 inches per octave, but there is nothing to indicate where the fulcrum would be - presumably this is in a higher level assembly that is not (yet) published.
They claim that it will be open source hardware, so hopefully ALL the mechanical drawings will be published at some point. [...]

Perhaps I'm missing something here...isn't there a bigger issue in that all keys appear to be pivoting around the same extruded rail line? That would mean there's no fulcrum offset for the black keys, which seems to me like it would make them noticeably stiffer, no?

I have literally just stumbled across this VAXMIDI thing and am intrigued but have a few major questions. Is it stated anywhere that it's meant to be a piano action? I understand the predecessor vax77 was mid-weight, closer to the vintage electrics...will be very interested if the vaxmidi is reasonably close to grand piano weight.

May have to hold off on the SL88 grand I was about to order

You may be right, although the force needed at one end of a lever depends not only on that side's length but also the length and force on the other side.
In any case, I still can't get even a .stp file of the individual keys (white OR black).
The octave_of_keys file is an assembly that I can't break down into its member parts to measure.