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  #1  
Old 10-09-2017, 09:04 AM
danjmath danjmath is offline
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LF help/critique with my Yanagi ba



I'm a pretty new knifemaker, and my current project is a stock-removal 200mm Yanagi ba using 1095 CRA.
I am using this knife as a learning experience. I have never done a chisel/single bevel before, never done a knife this long, and never clayed a blade/attempted to make a hamon before.
I am not expecting a masterpiece by a long shot, but I do hope to come out of this with a usable blade with a visible hamon for the next time I make sushi.

Not sure if it was during grinding, or when I cut out the blank, or if just came cold rolled that way, but my knife has developed a little bit of a warp. It seems almost arched in the middle.

Whats the best way/time to remove a warp like that.

Current the knife has been normalized (3 times to non-magnetic, air cooled), but not heat treated.



(Image is pre-normalization, but it looks pretty much the same, just a little darker steel now)

Plan is to apply some clay and try and get a Hamon, heat treat, try a little convex grind, and maybe even try to do an Urasuki on the back.

Now to the many questions...

Firstly, how\when should I remove the warp in the blade. I tried a little while I was normalizing, but not enough.

Second, given its current state, is there anything else I should do before I apply the clay and heat-treat it?

Third, after HT, my thought was to only temper once, 1hr at 400. Seems this type a knife would benefit from being harder, since I would only use it for making sushi, or maybe slicing boneless meat. Anyone see a problem with this?

Finally, any critiques on the shape/workmanship so far? It does not look quite "right" to me, I kind of free-formed the shape. Maybe its just because its short for a Yanagi.

Thanks for any feedback!

Last edited by danjmath; 10-09-2017 at 09:07 AM.
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Old 10-09-2017, 10:09 AM
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Ray Rogers Ray Rogers is offline
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A one sided grind is just begging for the blade to warp in heat treat. The best way to do that grind and avoid a warp is to grind after the HT is completely finished.

Doing one temper at 400 instead of two won't make any difference to the final hardness. If you want the blade harder you'll need to temper at a lower temp.

If you do get a warp the best time to remove it is as soon as possible. Even so, it is still probable that it will warp on the final quench. When that happens to me, I straighten during the temper cycles but it takes several temper cycles and many hours to accomplish (usually).

I think you're making a mistake to try so many new things on one knife. If it were me, I'd just HT the blade you have as it is and see what happens. On the next one I'd do the clay coating and grind the bevel after the HT was complete, much less chance of warping that way and easier to straighten if it does ...


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Old 10-09-2017, 10:39 AM
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Ed Caffrey Ed Caffrey is offline
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I agree with everything Ray said. Especially the part about trying too many "new" things at once. When you go that route, and something goes wrong, it's very difficult to determine exactly what it is/was that caused issues, and therefore that much harder to figure out/overcome.

One thing in the pics that caught my eye is that it appears there are still some very heavy grit scratches on the blade.... those are potential stress risers..... in other words, begging fractures/cracks to occur during heat treat. The rule in my shop is before anything goes to heat treat, there are no scratches anywhere, larger then 120 grit.


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Old 10-09-2017, 11:57 AM
dtec1 dtec1 is offline
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Ok see I am notorious for trying to many things at one (ray can verify that! LOL) but ray and ed are right usually when I do that I end up kicking myself in the butt....if you have a slight warp you can get it out in grinding.....when you buy steel its not perfect but if there is a warp its usually slight if its bad enough that you cant grind it out easily most likely you put that warp there one way or another.....also as ray said I follow the same thing I always cut the profile then heat treat then do the bevels I have done tons of blades this way probilly 95% of all the blades I have done...
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Old 10-09-2017, 12:17 PM
danjmath danjmath is offline
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I don't show the edge, but its fairly thick still. For something like this would you not grind at all pre heat-treat?

As per Ed's advice, I will go to at least 120 on the existing scratches before treating.

What is the best way to straiten during tempering? I have seen clamping to a file/other strait metal, but I have also heard some people say to "over-compensate" using shims.
Thanks for all the input!
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Old 10-09-2017, 02:57 PM
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Ray Rogers Ray Rogers is offline
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I don't grind any of my blades until the HT is finished unless I'm using very thick steel. But, on an evenly ground blade you can often do just fine and have little or no warp. The problem with your blade is that it is not evenly ground and therefore the probability of a warp is very high. Maybe a little warp, maybe a pretzel but some warp is almost inevitable.

When you first receive the steel there may be some slight warping that you can easily bend or grind out as you make the blade. But, all steel was very hot during the manufacturing process and who knows how it was cooled, rolled out into bars, sawn, sheared, etc any or all of which can induce stresses in the steel. When you get the steel it has been forced into a more or less flat shape but the stresses are still in there. As you grind the steel some of the stress that was holding the bar straight get removed allowing other stresses to bend the bar. If you can heat the bar first - as in normalizing - you can usually relieve these stresses but if the bar warps then it is easy to straighten because normalizing gets you into the red heat zone where the steel is soft.

If you have to straighten during temper the steel is only slightly inclined to moving and thus hard to straighten. My preferred method at this point is to clamp the blade in a 3 point jig and temper the entire thing in my oven. After a couple hours, pull it out and tighten the bolts down and put it through another temper cycle. Keep doing this until you think the blade is likely to be straight or until you have the bolts fully tightened. Then let the entire thing cool to room temp before releasing the bolts.

I made my jig from two half inch bars of mild steel from the hardware store and two half inch stainless bolts and nut (use stainless so the heat doesn't oxidize them to the point they become useless). The 3 points are three sections of 1/2" mild steel rod from the hardware store and the whole jig is about 2.5" wide. The little rods are not attached to anything so you can place them anywhere you need them...


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Old 10-09-2017, 03:34 PM
epicfail48 epicfail48 is offline
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Another vote for not trying too much new stuff on one blade. The blade style you're going with is already a bit of a challenge, long blades tend to warp, asymmetrical grinds tend to warp, 1096 tends to warp, and clay coated blades tend to warp. You've really got a perfect storm for making a pretzel going there.

Can't say ive got much advise for straightening for you either, I've not had much success trying to straighten a knife post-ht. Generally you want to find a way to force the blade to bending the opposite way of the warp and keep it that way for a tempering cycle, but I almost never get that to work. Either it doesn't straighten, or it snaps. I've started grinding my bevels after HT for most of my 1095 blades, then warp doesn't really matter much. The one exception is hamon blades, those pretty much require grinding the bevels before HT, and keeping fingers crossed it doesn't warp too badly.

I'd skip the clay coating for this blade, HT it normally, see how it moves and use that knowledge on the next one. Best to learn stuff in small increments, rather than all at once. I know Walter Sorrels has a video on how to make a Yanagi-Ba on hit YouTube channel, may be worth a look.

Oh, last thing, never get too attached to a 1095 blade before you heat treat it, especially if you're going for a hamon. You can get away with a slower quench medium like canola oil on a relatively thin blade with bevels pre-ground, sometimes, but getting good hamon activity and even getting full hardness on some blades requires a faster quench. Generally, that means water or brine, and if you want to see a bladesmith cry, ask him how many blades he's lost to brine. If you plan on working a lot with 1095, invest in some Parks 50. Almost as fast as water, doesn't crack blades nearly as much
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