Study on the hot-dog-in-a-bun welding technique

[Sam Salvati]

I have been studying the construction techniques of Japanese bladesmiths, I call this stile of a soft steel jacket over a hard steel core "hot dog in a bun" because that's what the preform billet looks like . This method is common in Norway and Scandinavia also for pukko knives, however I was told by a smith from Norway they use angle iron for the jacket in modern times lol. I tried it for the first time yesterday, and succeeded so, since "this thread is useless without pictures" I thought I'd do one better and make a video. Thought you guys over here in the custom knives section might be interested to see it too.

I managed to capture everything but forging the blade out before the memory ran out, but the major parts are in there, I hope it's clear but if anyone has any questions feel free.

[youtube]NwRsT0PWBZU[/youtube]

and here's the knife I ended up with, I forged it by hand a bit after the video, then cleaned it up on the grinder.

 

[Shawn fu]

Great video,Sam-maybe a stupid question,but how are you cleaning the scale out of the slot before you place the bit?
btw-cool little cleaver

 

[Burton Harruff]

Cool video Sam and nice cleaver. I was curious about the scale also.

 

[Sam Salvati]

This follows along in the Japanese school of thought, which to my understanding so far follows more along the lines of blacksmithing then the uber cleanness and perfect tight press fits of the American school of thought, atleast when it comes to knives and tools. So in other words, it's whatever the flux doesn't spit out stays there, it's still an excellent structural weld, the pieces are as one, but it's not necessarily the cleanest weld, or certainly not a surgically clean weld like we are more used to seeing. Many a billion welds have been made in ornamental ironwork where the welds were only scarfed fluxed and then welded, as well I guess many a billion tools have been made using this method. If I notice alot of scale in the slot first I will run a wire brush through it, but on the two I've done if you "planish" the slot working the chisel tool into it at a lower red heat before fitting the bit in you knock out most of anything that's in there.

This kind of sounds like I am trying to justify substandard practice but I don't mean it that way, it's just another outlook.