what kind of spring for a treadle hammer?

[TemplarSmith]

Im sure this has been answered so im sorry. I tried searching the forums and the internet for it but i couldnt find anything helpful.

 

I just need to know what type of spring you would use for a treadle hammer? And maybe a rough ballpark of how strong it should be?           (i know nothing about springs)

 

Its for a very basic treadle. Probably like a 10lb sledge.

Thank you for your time!!!

[Charles R. Stevens]

The short answer is the one that works. I have a 14# sledge and am using a trampoline spring. You need a spring that will hold the hammer up at rest and won’t kill you when you tramp down on it. Springs are generaly rated in inch/pounds or The metric equivalent wich can be mm/g, cm/kg or such. As a spring stretches or compresses (depends on the spring) it gets harder to deflect. Unfortunantly I don’t know a hard and fast rule for it, but understanding that the farther the head is from were the spring mounts makes it weaker (leverage) allows some adjustment .

In the first picture you see the length of the spring wile at rest and wile holding up the hammer. 

In the second you see the two adjustments built into my hammer. The chain would shorten the spring thus making it softer wile the “U” bolt allows some adjustment to the leverage. 

In general the less coils and the bigger the wire size the stiffer the spring (leaf springs work a little differently, thicker the leaf, more leafs and shorter the main leaf the stiffer). 

Note I don’t say “stronger” as a strong spring may not be as stiff as a week spring.

Generally the more coils the less stress on the spring, so it lives longer and can stretch farther. 

This is a bit simple, as torsion springs are a bit different and can be used as well. Their are two kinds of torsion springs, one being like a clothes pin or a self closing door hinge. 

Wile another is like the torsion bar on your car.  

But this should give you an idea.

 

[Frosty]

Welcome aboard TemplarSmith, glad to have you. If you'll put your general location in the header you might be surprised how many members live within visiting distance. 

Charles covered the basics pretty well, I only have a little to add. It's better to use too light a spring than too heavy, it's really easy to add another light spring. If it's too strong you may have to replace it. The upside to having to replace a too  heavy spring is springs in your resource bin are always handy things, lots and LOTS of useful things can be forged from springs. 

Anyway, if you make the mounting points wider than the one shown by Charles you'll have room for another spring or two. No  need to get carried away though, I've known guys who used 6-8 screen door springs. The treadle hammers worked just fine but all those springs rubbing against each other sounded kind of creepy weird. Like a camp fire ghost story door opening in a dark room. 

Frosty The Lucky.

[BIGGUNDOCTOR]

The one my Dad made has two garage door springs on it.

[Irondragon Forge ClayWorks]

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