Small, cheap extension springs?

I'm looking for small (about 3mm diam, 3-4cm long), not to strong, cheap extension springs for my console project, to hold back the stop tabs. I've looked at a number of suppliers, but the prices seem unreasonable to me. The cheapest options are around 1.30USD per spring (this is including a volume discount when ordering 50 of them), and even buying 1000, the price is about 1 USD. I need at least 41 of them, which would mean to spend above 50 dollars on the springs. In comparison, the MIDIbox Core, two DOUTs, cables, connectors, 41 LEDs together cost about the same.

Is there anyone who knows about a cheaper source for these small springs?

Imre,

Could your design be modified to use piano wire more directly in some way?

It seems much cheaper if you "roll your own".
http://www.pianosupplies.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=PianoWire

Regards,

Is there anyone who knows about a cheaper source for these small springs?

Hello Imre,

don't know if this is of much help, since it is a German company. I ordered springs from "Gutekunst Federn" (http://www.gutekunst-co.com) for pretty much the same purpose, and I ended up paying 0,31 Euro/spring (I ordered 37 springs). On their website they have a good selection tool and you can order exactly what you need.

Hope this helps
Reiner

You might also check on ebay. Even tho you are looking for extension springs, I entered compression springs and found several possibilities. A few numbers you may want to check out - 180396004964, 120455432674, or 120456462952

Any of these are cheaper than your quote. I couldn't tell the spring force to compress or extend them. Some look to have fine spring wire..

Rgds,
Ed

Thanks guys, I knew there had to be some cheaper supply options.

Re: piano wire: what size should I use? I think even as thin as size 5 or 6 should be fine. How easy is it to work with them? I tend to like this solution, as I can make the springs as long as I want.

Ebay is funny: there are pretty much no relevant hits for extension spring, but there are some good ones for compressions springs. I wasn't even searching for the latter one, as I need extension springs. (I'll need compression springs for a long-term project: DIY combination pistons.)

Without knowing exact specifics, this could be a typical spec for small, piano wire extension springs for your application:

Overall length 1.0 inches
Outside diameter 0.25 inches
Wire diameter 0.026 inches
Spring rate (force) 2.80 -3.30 inch pounds

Just a (hopefully) good guess. I think you might encounter a uniformity issue by "rolling your own".

Rgds,
Ed

I think you might encounter a uniformity issue by "rolling your own".

Yes, this may be a problem and you will almost certainly need to provide some sort of adjustment to compensate for the slight variations in rate. I've made (literally) hundreds of small springs for various keyboard conversion projects and it's difficult to get true consistency even using a carefully set up screwcutting lathe to make them. I've only made compression springs, since these are much easier to make in bulk.

I settled on 0.5mm (0.020") carbon steel piano wire for my particular application. If you want to try making your own I recommend K&S metals who
distribute their products via craft and hobby shops worldwide and offer piano wire in a range of gauges at a reasonable cost for experimental purposes. Having decided the size that suits you can try and source the wire in bulk (as I did) for a lot less money.

Nick