[TheForge] Treadle Hammer Springs

[xlch58 at swbell.net]

Steve Smith wrote:
>
>
> Bruce Freeman wrote:
>
>> Rumor has it that multiple small springs are better
>> than one large spring, and you see some treadle
>> hammers so constructed.  I haven't given this enough
>> though to explain why this should be true.  It MIGHT
>> be true because garage-door springs take a load to
>> even BEGIN to extend, whereas most small springs
>> don't.
>
> This never made sense to me. Spring constant is spring constant, no 
> matter whether it comes from a bunch of small springs or one large one.
>
> Changing the spring constant, however, is another issue.
>
> Steve
Some springs are progressively wound, so depending on extension ( or 
compression) the spring constant changes.  Good reasons for doing this 
are to allow easy installation on a strong spring.  Other springs are 
wound with an initial tension.    Finally, common extension springs do 
not have a constant rate, their behavior is most linear in the middle of 
their range.   There are in fact a special class of extension spring 
call a constant rate spring.  So depending on the design, a bunch of 
small springs could be put together in such a way to give a more 
constant rate, or  to provide a progressive rate.

Charles