Hi, all.
I know there are a lot of factors affecting how soft/firm a mattress feels, but specifically about coils:
-1- Can someone explain the effect that coil height has on softness/firmness for a given gauge? For example, is it correct that 15ga in a 4" coil would feel softer than 15ga in an 8" coil?
-2- What about number of coils? If you have 1000 coils at 15ga, would that feel firmer or softer than 750 coils at 15ga?
Thank you.
With respect to question 1, the spring constant expresses the force per unit length of deflection, i.e pounds force per inch of deflection.
The basic equation for a spring with round wire is k = Gd^4/(8n*D^3). As you can see, if all else is held constant, then as n (the number of turns) increases k (the spring rate) decreases, where n is the number of active coils (the turns that can actively compress). So the spring rate, with all other things being equal is a function of the number of turns, rather than the spring height.
[quote=“susu123” post=88047]
-2- What about number of coils? If you have 1000 coils at 15ga, would that feel firmer or softer than 750 coils at 15ga?
.[/quote]
It would be firmer if all else is equal (i.e. G, d, n, & D) . The same load would be distributed among more springs, so each spring carries less load, and the deflection for each spring would be lower.