yanagi-ba question

[jdm61]

I want to try to make a honyaki yanagi-ba using "modern" methods, which is to say, digitally controlled HT oven, propane forge, KMG, Nathan radius platen and platen chiller, etc. My question is should I try to forge in the main bevel or just make a flat tapered blade "blank" and grind in the bevel and the convex back after HT? I will likely be using W2 initially, but I would like to eventually score a bar of Hitachi White #2 from Dictum. Also, if I do the unleveled blade HT, would that say that I should probably use a brine quench even on the W2 to make sure I get sufficient hardness?

 

[BluntCut MetalWorks]

Water quenching steels have higher dimensional delta between aust & mart structure. So for a complete harden blade, I would post-ht grind the whole blade - chisel & hollow back. For edge quench or tall hamon (~2/3 blade wide), pre-ht grind front & back are pushing the luck on no-warp.

IMO - For unbevel blade(80 or 120 grit surface ground) ht of 5/32 or 3/16 x1.6" W2, dip & slice brine for 3 seconds (goal try to cool down to around 500-600F), plate quench to room to minimize distortion. For clayed blade, dip & slice brine 3.5 seconds, rapid agitate in warm canola (much cheaper than pollute p50) oil to below 200F, wash.

 

[jdm61]

Thanks. I already have Parks #50 so no need for canola or heating.

 

[Willie71]

I grind half way to finished dimensions with shallow hardening steels, heat treat, then finish the grinding. That gives you geometry for the hamon to follow, some room to correct warp, and the rest of warp correction happens in temper. A thin kitchen knife with a hamon is more time consuming to finish than a large Bowie.

 

[jdm61]

In my experience a thin double bevel kitchen knife wth a hamon and a bowie with one are equally time consuming, which is to say, they take a darn long time. But then again< i leave W2 boiwes pretty hard too. I found the I can cheat a little bit on the grinder with a kitchen knife grading lengthwise because there is no plunge cut to potentially screw up.

I grind half way to finished dimensions with shallow hardening steels, heat treat, then finish the grinding. That gives you geometry for the hamon to follow, some room to correct warp, and the rest of warp correction happens in temper. A thin kitchen knife with a hamon is more time consuming to finish than a large Bowie.

 

[Willie71]

In my experience a thin double bevel kitchen knife wth a hamon and a bowie with one are equally time consuming, which is to say, they take a darn long time. But then again< i leave W2 boiwes pretty hard too. I found the I can cheat a little bit on the grinder with a kitchen knife grading lengthwise because there is no plunge cut to potentially screw up.

Yes, they both take a long time, but I often have to run multiple temper cycles to correct warp with a kitchen knife, but usually have a Bowie straight after one or two cycles (if it didn't come out straight in quench.) I've noticed hitachi blue comes out pretty straight from quench for some reason. Maybe just luck on the last few blades.

 

[JMJones]

Due to the yanagi being asymetrical, you are inviting significant warps by forging in the bevels on a mono steel blade. As they are traditionally made with a liminate of non hardening steel you can straighten much easier after heat treat than monosteel. I would grind both sides after heat treat is complete.