Buying mechanical parts can be a real pain because you're just supposed to
know where to get them. Nobody writes books on how to do it because
everybody knows, and the rest of us don't try because we don't know enough.
Springs are going to be like inductors -- everybody wants something
different and they're easy to wind. This means that they're mostly custom,
so if you want them in quantity you can probably get them made to order. I
would approach this in one or both of the following ways: try to find
someone yourself, and get professional help.
To do this yourself do a web search on "spring manufacturer" or some such,
and call. Make sure that you have a notion of your planned annual purchase
or your one-time buy amount (you know this, right?). If they have a sales
rep who's local you should be able to give them a sample off of a 100-in-one
kit and say "I want that".
I was in the act of suggesting nickel-plated beryllium copper for the spring
material, but then I remembered that beryllium is quite toxic. Marketing
this to kids would be a _bad thing_. You want to be sure that when the
18-month old little brother rips all the springs off and eats them nothing
bad will happen. This would explain why most of those springs seem to be
nickel over steel. My understanding is that chrome is fairly rigid, so
it'll probably be more prone to flake off (and it's toxic to, but if
frequency of warnings are a measure then it's not as bad as beryllium).
Nickel will be more likely to flex. You should _seriously_ think about
having the springs plated with copper first, then nickel (don't believe them
when they say they can plate the nickel straight onto steel -- that's just a
good way to make little shiny flakes).
For professional help (not _that_ kind, people!), find yourself a good
consulting mechanical engineer who makes mechanisms and gizmos for people.
He (or she) will know a few companies to talk to, will be able to translate
your desires into specs for the spring company, should be able to give you
better advise on plating, and will be delighted to take your money. If you
can afford it this it's a very good way to go. Your spring manufacturer
will want to do some of this for you, but there will be no disinterested 3rd
party looking over their shoulder. If you live close to Oregon drop me a
line and I'll recommend a few names.
Good luck, I hope it'll be part of something as neat as what you've got on
there already.
