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Billet size for Wrought iron San mai


Aaron Gouge

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Hey all, 

    I had a good friend give me some wrought iron and elk antler. He want a couple knives made. I have not done a lot of forge welding. I am hand forging everything. Will be using 1084 or 1080 as my core.  What billet size should I be starting with to forge a  4”-5” hunting knife. How thick should my layers be? Any general tips for San mai wrought . 
     Thanks all

Aaron 

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Well I started with a pairing knife. 1080 core with the wrought iron jacket. My pieces were 1” wide 2.5” long and 1/8 thick. Had no excess metal. 

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1 hour ago, Aaron Gouge said:

Well I started with a pairing knife. 1080 core with the wrought iron jacket. My pieces were 1” wide 2.5” long and 1/8 thick. Had no excess metal. 

 

Looking good!

 

I don't think there's any rule for the thickness of the layers, it'll depend on what you're trying to achieve and what your margins are. For a straight laminate like you did here you could get away with fairly thin layers if you forge somewhat close to finish. If you were to manipulate your cladding pattern before welding it on (for instance by twisting the wrought iron first -- though that can be challenging with wrought iron), you'd want to keep it a little thicker in my opinion, so that you have more control over how deep you grind into the twist.

 

It can also depend on how you forge: my understanding is that a lighter hammer will tend to spread the outer layers of a billet more than the inner ones, where a heavier one (or a power hammer) would distribute the force deeper, and spread all the layers more equally.

 

Also, the thicker the cladding layers, the more challenging it is to keep your core centered throughout the forging and subsequent grinding. When in doubt, etch.

 

A good way to figure this out for yourself is to start with equal thickness layers to see where that gets you, and then make changes as needed.

 

Caveat: there are way more experienced people than me on here, so if they disagree with what I said, trust them instead of me ;) 

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With wrought, it's usually a good idea to keep the wrought layers half the thickness of the core steel.  The wrought will indeed spread more, which can lead to it being exposed on the edge or tip.  But that's if you're doing a lot of forging.  As Francis said, if you're just welding and grinding it isn't as big a deal.  

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Thanks Francis and Allan, that all seems to make sense. I will be forging the shape to about 90%. I normally forge in my bevels but on this one I ground them in. I wanted to keep it simple. Would you forge the bevels in on a larger piece? Or forge to shape and grind in the bevels? 
     Aaron 

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