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Trailer Spring Crossbow


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Hey guys,

I've been working on a crossbow for a client. If anything, I've learned being self employed is pretty crap.

 

Anyway, I'm using whats about a 1/4 inch trailer spring for the prod (bow portion). I made a mismeasurment along the way. Without thinking, I filed the spring. As I did so, I realized it should actually be very difficult, but the file has no problem scoring the metal.

for the moment, I will continue working. is there something wrong here? it has been sitting in the garage for a few years, but can a spring lose its hardness?

 

Am I fine, or am I throwing it in the forge?

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Springs are "SPRINGY" NOT hard. Being 60pts. carbon means we can make it coffee mug hard doesn't mean that's what's needed for springs.

You can drill spring tempered 5160 with HS bits, cut it with cheap hack saw blades and mark it with a wood rasp let alone steel files.

The chrome in the alloy is there for abrasion resistance in stacks, not structural hardness.

You don't have a problem with weird stock, it's as it should be.

Frosty The Lucky.

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Steel prods were never the bst choice for crossbow prods, the were relitivly inexpensive and expediant. organic composits have much faster casts, but take much longer to build, and are muchmore suseptible to dammage, be it water or abuse. Steel is much better when you are training the lowest common denominator insted of recruting experts.  

Read up on "tillering" and basick bow making so you understand how to design a bow, and how to shape and adjust the limbs. 

Look also into "reflex" and "recurve" limb design. 

Personaly, ou side of the lock and trigger, i would not chose steel, black colored fiber glass backed buy "action wood" and an backed buy yellwish glass would make a good aproximation of "composit" and as composit bows and prods were usualy raped in thin skin, it would be hiden. Horn, wood and sinue composits are very technical. 

This would provide a durable, reliable and very fast casting cross bow. Otherwise comertial prods are relitivly cheap, and some one else is liable

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I've made them from leaf spring. Note the above third conversation listed by Steve. I never had one of mine from used steel fail, but they can, and when they go, they go big time.

I wouldn't chance making one that way again. If ya want to cut down spring, find a spring shop and got drops from new steel. 

Rather than a long, lighter draw, crossbows tend to have short draws running into the hundreds of lbs range. Imagine one flying apart into pointy sharp shards of steel under hundreds of lbs of pull and just for fun a nice pointy bolt added to the mix.

And that's before you get to the part where you're thinking of trying to evenly heat treat something that size from mystery steel.

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