Hello folks. New here, and looking for some ideas/advice on a very unique problem.
I work in a research lab, and we're looking to do a study that will involve piano playing. The twinster here is that due to the experimental setting, the device that subjects will use cannot have any ferrous metal in it. It does not have to actually make noise (as this would be nearly impossible, but ideal) but needs to "feel" as much like a piano action as possible.
One immediate thought would be to take the action off of an old piano as a set and break it down as far as possible. However after lookin at a few diagrams online, I get the impression there are lots of little pieces that are metal, and I wonder how much can be removed and still have mobile keys.
As a note, other metals such as brass, tin, aluminum, etc are fine. Even very small ferrous bits *might* be okay if they do not move at all.
For example, what is the balance rail bearing made of? Perhaps this could be replaced with brass?

Does anyone know of a type of piano where most of the pieces would comply with this? Perhaps one where much is wood... or an "el cheapo" made of plastic?
Another route I am considering is stripping apart a plastic toy... problem there being the "realism" factor.

Thanks, I'm open to ideas.

Most piano actions do not have any moving ferrous metal. There are some screws and brackets, but they hold things in place. Most of the moving metal is brass or bronze springs, and brass center rail pins. Modern piano actions may have aluminum brackets and rails.

Hire a tech to take the action out of a piano, and then you can test it with a magnet.

If you do not need to produce any sound, you should be able to use a grand (or possibly an upright) keyboard and key frame, with the action removed.

There will be very little, if any, ferrous metal in the parts. Keyrail pins (balance and front rail), for example, are plated brass. Possibly there are some wood screws in the frame which could be replaced with brass.

You could add lead weights to the far ends of the keys so that the touchweight is equivalent to that of a keyboard with action.

Piano actions themselves sometimes contain some substantial ferrous metal in the action brackets. It will be difficult to replace these.

Another choice would be a weighted keyboard which is used to control a midi sound module. Such a keyboard should contain little in the way of ferrous metal.

Would the study you are considering be using PET scans to measure brain activity during keyboard playing? If so, I am wondering about the lack of sound feedback to the player and its effect on brain activity.

I have seen brass key pins (rarely), and mild steel plated key pins (mostly), but never plated brass pins. Check them with a magnet.

Every wippen has ferrous metal parts: regulating screws for jack and balancier, the balancier "up-stop stirrup", the jack button spoon etc. For a lab test sitution, these could probably be replaced by brass, or even done away with, depending on what is being tested for.

As for a plastic action, there were a few makes out there that were made out of plastic - the Lindner and Helpenspil (sp?) come to mind, but if memory serves me correctly, the plastic mainly replaced wooden parts, and the metal parts remained.

From a former rat-killer:

Sounds like you're going to have to make a grant proposal. Without knowing more about what you're after, it's hard to tell. But I think it "could" be done...but you're going to need a willing (meaning well-paid for the time and trouble) technician.

Doesn't Kawai have some non-metallic action brackets...Millenium? Those cool looking black ones?

When you say ferrous, do you mean ferromagnetic? I ask because many stainless steels are barely magnetic (316 comes to mind)and would be a good replacement for some of the steel parts that are in the action.

All the action parts that are some steel alloy could be changed for parts made of other alloys. It's only a question of time, both for the guy playing with the action, and someone machining/fashioning new parts. Plastic is not a good option for replacing the existing metal parts of an action.

Jurgen is quite right. There is plenty of ferrous metal in a keyframe in the key pins. What was I thinking about? Perhaps a certain harpsichord.

Sorry for the lag in getting back. Busy day.
For clarity - yes, ferromagnetic. E.g. nothing that could potentially have even the slightest magnetic pull or field. "barely magnetic" is still a problem, e.g. stainless is out.
Casalborgone, you are on the right track, but this is for MEG, a method where you record magnetic fields in the head, not PET. Incidentally, metal and a keybaord are no problem for PET, in fact there have been some great studies done w/ piano playing in PET.
Yes, it would be ideal to have direct audio feedback... however this is ssomething we can live without if necessary. They probably will be "playing" along with a pre-recorded clip anyway.
John - I'm sure a grant is in our future. However as I'm sure you know, *getting* the $$ typically requires first having proof of priniple. Classic catch 22! My guess is that yours truly will be putting in the work...
It is all those little things that Supply mentions that have me worried. When you ay "key pin", which part do you mean? Would that be the "balance rail pin" in this diagram?
http://www.musicplay.com/action/action.html
(not being a piano tech, this is a lot of new termminology for me!)
I am actually wondering if the whole Wippen assembly could be removed, since I do not need to strike a string. I really need only for the keys to rock and have some spring action.

I like the comments, please keep them coming!

Talk to a harpsichord maker. There is only a balance rail pin in some harpsichord keyboards. You could easily fabricate a plastic spring for this purpose: just cut fingers at the edge of a sheet.

Rat - first you say your model "needs to "feel" as much like a piano action as possible.", then you suggest removing the wippen (and by default, the hammer.) These two scenarios are mutually exclusive.

Losing the wippen and hammer would more or less eliminate ferrous metals, if brass key pins are used. If a simple lever (key) with a fulcrum and a spring will do, great! But don't expect pianists to have the sensation of playing on a piano. The touch of a piano is very complex, with inertia, component weights and spring tensions all playing a role, not to mention two or three pressure points in the course of one keystroke.

In a piano, each key has two guide pins - a front rail pin (not on the diagram you linked to) and a balance rail pin. As mentioned, these can be made of brass.