Re: Speaking of folder springs...

Is there a guideline, or, ideally, a formula to calculate the
proper spring dimensions?

For sure, science and math could be applied to that.
In this case "art" is easier tho, as in, "copy it". ;)

I believe the critical paramters would be: Spring length (from
center pin to end, and from center pin to *** pin), spring
thickness (thickness of the stock from which spring is cut),
and spring width.

Yeah I've noticed that. As if, there's a certain amount of steel is
needed... so a thick spring doesn't need to be as wide to get the
same action.

In other words, for a given spring length and stock thickness, how
wide do I cut/grind it to get an appropriate 'snap' to the action?
Kelly

Depends on the length and weight of the blade? And how much "pre
stress" (really should be pre-strain but hardly anybody uses it
right;) you apply to the spring is another factor. And how much
pre-strain can that particular spring's metallurgy/heat treatment
handle before it relaxes to a lesser amount of pre-strain anyway?

And the camming action of the tang too. :/

For a Case 6375 clip blade... and 7/64" thick springs... about
square in cross section if you want it stiff, sometimes the factory
springs are a little "less" than square where they've cut down into
it at the lowest point.

For my one-time-shot at a ~5" light weight blade at 1/16" thick with
1/16" thick spring, I went 3/16" wide. "about triple"

For a brand new 3/32" spring I start them about "double" but figure
on removing at least a quarter of that from the back-of the spring
as it's fitted to the scales etc. I like them stiff. Sometimes if
I'm not paying attention I rip a hunk of thumbnail off instead of
opening the blade. :) YMMV on that. ;)

Never really thought about this much before, it's always been such
a "seat of the pants" sort of thing after seeing so many dismantled
factory pocket knives. :)

Alvin in AZ
ps- "pre-stressed concrete" is like a truck's "pre-stressed" flat
trailer you can see the upward-bend before the load is applied
pps- problem is, stess is "the load" and strain is "the bend" so the
hump-backed empty flat truck trailer is really "pre-strained"
ppps- I'm edjeekated, ya see, I took me a medullergy class ;)
.