Spring calculator

Does anyone have a good spreadsheet and or links to good (free) websites that calculate parameters for compression and extension springs?
I've found one or 2 links that are OK up to a point, but none are ideal.
My immediate need is to be able to calculate the maximum safe working length of an extension spring of known dimensions. The material is galvanised music wire, but I don't know what its safe working stress is considered to be, nor do I know how to calculate the stress for a given extension of this particular spring.
Any help would be appreciated.
Regards, John H
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The best I can think of is MITCalc. It has lots of sections, one of which is springs. I haven't looked at it for your question, but it might do it very well.
WT

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Google "advanced spring design" . Its not free ( ~$700 ), however there is a free trial period which may be long enough for you. Its highly robust software specifically tailored to spring design.
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Brian Hokanson
Starting Line Products
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Hi John
www.leespring.co.uk
pick the select on line button top right
select spring type, then find spring by specification.
they have 3d models as well, in fact I'm pretty sure they use SW
steve
John H wrote:

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On Mon, 7 Aug 2006 16:20:56 +0100, "John H"

I've used the Engineer's Toolbox. It works well and gives data you can copy and paste into a SWQx drawing for the spring manufacturer.
http://www.engineerstoolbox.com /
The online version is free, but there is a stand alone app that you can buy.
==========================================================================Chris
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This isn't free, but the Spring Manufacturer's Institute has a Handbook of Spring Design for $15 and an Encyclopedia of Spring Design for $48. They also have $600 software.
http://www.smihq.org /
For an extension spring, you usually need to calculate the stresses at the ends and this will depend on the exact configuration of the ends. The allowable stress depends on the diameter of your wire (smaller wire is stronger) and on the loading conditions (static or fatigue). I don't have any idea how the galvanizing effects the strength of the wire.
If you don't find something better, I could walk you through the equations from the design handbook for your particular spring.
Jerry Steiger Tripod Data Systems "take the garbage out, dear"
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You could try winFSB 6.1 I have used it for a while and seems to be reliable, its free.

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Thanks for the suggestions - some of them look useful.
Cheers, John H
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