[sdiy] Synth Keybards and Number of Keys

[Edward King]

John,

I actually gave more thought to the methods Id tried before and the ones you 
mentioned in your post.
Ive always been an avid fan of composites. Fact is, the things I fly would 
never get off the ground without them so to me they're much much more than 
just a very accessible plastic-type approach to construction.

So as I said, your suggestion provoked / rekindled interest in a design area 
Id treated as a dead end.
And then I got to thinking about the various ways in which problems are 
attacked in the sailplane and light aircraft arena.

The "hollowness" I didnt like in the keys I put together could simply have 
been approached in a slightly different way. In a sailplane spar for 
example, one uses a D cell structure. Of course this isnt appropriate given 
that the shape of the piece in question is restricted. An internal component 
similar to this might be one way to go though.
another alternative might be to fill the void with something light but 
"damping" such as balsa wood.

I would hate to leave you with the impression that I dismissed such a grand 
idea out of hand becuase in truth there are real benefits to this method and 
many would benefit more from using this method than the way I have 
eventually tackled building a homebrew keyboard. So my advice to anyone 
wanting to build their own would be "Do it this way!" but with a few 
modifications of the basic:

Plug -> Mold -> Piece approach.

One of the benefits of doing it this way is of course that you end up with a 
very smooth, shiny piece which is easily coloured and very, very tough.
However, I think it is necessary to point out that - at least in my 
opinion - you need to insert a couple of elements into the piece during the 
layup of the fabric. This would probably take the form of a steel or 
aluminium bracket to mount the pivot technology to (whichever technology 
that may be) and at the rear for the return spring (if indeed you are doing 
that).

I will try and throw a carbon fibre version together over the weekend and 
take some pictures. I dont think this list allows pictures though so any who 
want them will have to ask and I will send them individually.

Rest of your comments addressed in-line

Regards

Edward



>
> Thanks for the reply Edward.
>
>> Yes, I looked into this. I build my own GRP and carbon fibre  panels, kit 
>> and sailplanes and experimentation led me to the  conclusion that I didnt 
>> much like how they felt.
>
> What was the main issue you felt here? The light tap of fingernails  on 
> the key sounded plasticky?

Partly, yes. plus, you can actually hear that the keys are hollow. Some 
damping or somesuch is necessary IMO


>
> I think any kind of weight and feel could be introduced through a 
> combination of silica microspheres and fine metal powder or slate dust.
>
> The microsphere silica stuff is like this:
> http://www.fusokk.co.jp/eng/product/elec/003.html
>
> Mixed with polyester resin and perhaps a little bit of chopped glass 
> strand it makes a lightweight yet extremely strong paste that can  fill 
> the key shape and be used to 'deaden' the feel of the key. A  suitable 
> amount of the metal powder or slate dust could be added to  the paste if a 
> more solid key thud is required.

This is a good way of filling things out. Microballoons are used extensively 
in sailplane building as a filler and the end result is strong, tough and 
easily worked.

>
> Once the mix of filler is right, it can be made up and stored dry for 
> later use and consistency of feel.
>
> I am not sure how weighted keys work, don't they have a kind of  weighted 
> slingshot thing that swings back out when pressed, to  simulate a piano 
> hammer action?

Techniques vary from the one you describe here to rotary inertia devices, to 
balanced springs and levers to blah, blah blah.
Every man and his dog has come up with a way of making keyboards feel more 
like pianos. The closest ive ever felt was the Korg stage piano which uses a 
reduced size (but increased mass) version of the piano hammer action.

>
>> my point remains the same; custom building your own keyboard neednt  be 
>> expensive, can be much cheaper than a commercial product and is  - IMHO - 
>> nowhere near the most expensive part of a synth.
>
> I do agree with you.
>
> I haven't built a synth from scratch since 1978, but I still have a 
> couple of spare keyboards. One has square fronted keys, one has  slanted 
> back fronts. I will see if I can take them to pieces and cast  some key 
> sets successfully, when I get time.
>
>> The GRP / carbon fibre method would work well though for those who  want 
>> to build their own plastic type keyboards.
>> Perhaps you should create a tutorial for those who arent au fait  with 
>> GRP and carbon fibre techniques and put it on your (or someone  elses) 
>> website. I would bet a fair amount of money that others  would jump at 
>> the chance to roll their own using your method.
>
> Yes maybe I should. I was a professional modelmaker in another life.
>
> John
>

You probably have a skillset then which is already way ahead of someone 
trying this for the first time. I remember my first forays into composites 
and they werent pretty.
Expense, mess, coughing fits and unpopularity resulted and the final results 
could be considered "art" they were that bad.

If you do cast the keysets, can I buy a set of moulds please or would you 
only be interested in selling the actually pieces?
I want to add as many different types of keys to my collection and so Im 
also interested in some of the rarer "rationalised" keyboards that have done 
the rounds over the years.



		
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