Drawing out a San Mai billet

There is some lovely blades men.all of them
I may take some pics of a knife of mine and try figure out how to post.hope it's luddite simple
Im only forging about 3 months but all day every day in that time
I only forge by hand
I forge out my San mai like I would a round bar,as in short wide stack forged out,rather than try to forge laminate it if you get me. the finished blade feels better to me that way
 
John, are you saying you use thick (>1/4") bars for your San Mai? Say 3 layers of 1/4" would give a 3/4" thick stack, then draw that down to the final thickness you desire? That much drawing down I'd have a really hard time keeping the core centered. I have hard enough time with using thin layers. It seems my outer layers tend to draw down much faster than does the core.
 
The softer outer layers will draw faster.

For the billet, I suggest 1/4" sides on an 1/8" core, or 3/16" sides on a .090/.100" core.
When finishing the billet to size, forge the edge as needed so the core is pretty straight. It isn't an issue what the spine or middle of the blade is like as long as the edge is centered. Grind the edge frequently and dip in 5:1FC to check the core straightness. Do the same as you forge or grind the blade.
 
Ken I used about 8mm mild steel outer layers and about 6 mm core and whatever the bandsaw blade measured. Was about 1" thick and about 7 " long
It was an integral bolster knife so I needed that thickness
I kept an eye on the core by just grinding the spine and edge every now and then and quick etch but only couple of times,after finishing forging I spent a couple of heats fine tuning core
 
I like that idea Stacy - I stick weld to seal the billet for dry forging I'd set the welds. Once I'm sure the welds are set over the total billet, I'd remove the edges back to where the core is showing good. Once I've got the core exposed and etched to show, then I'd put in forge to start drawing the billet. Hammer a bit being sure I've counted blows on each side, then cool billet, grind edge clean, etch to show core. From this I can see how well the core is centered, and where I might need to hammer to even up core some.

Thank you for these ideas - I think this will help me with keeping the core centered. I like the idea of core being half thickness of the outer layers. This last billet all 3 layers were pretty close to the same, and with the outer layer being 416SS it's a lot softer than the 15N20 core. This is why my core hasn't been moving near so much as the outer layers - it's harder, even when at forging heat the 15N20 which is around 43 Rc being a harder metal doesn't move as quickly as the softer outer layers. This is really evident with mild steel as outer layer.

Boy am I learning a bunch with help from a GREAT bunch of folks here. Thanks Stacy for being a good moderator and sharing your knowledge, and thanks to all the other folks here for sharing.

Ken H>
 
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