Clay coat along spine question

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DaQo'tah Forge

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I had a bend to the side in my newest Katana after the water quench, so I was working it out in the vise when the blade snapped.

This is the 2nd time I have done this error.

I think I need to have a stronger yet softer spine to learn with. Now so far I have always scrapped off the clay from the spine edge to allow that area to harden in the quench. But for this next blade I plan to cover the whole spine area with thick clay.

what do you think of my plan?

Do any bladesmiths ever cover the whole spine of the blade with clay like this?
 
Most smiths cover everything except the cutting edge. If oyu leave it exposed you have a hard spine and a hardned edge and a soft core in the middle. You are losing some of the flexibility. Try warming it up with a torch in the area of the bend next time, just don't get it too hot! Then streighten. Or streighten as soon as it comes out of the quench.
 
ok,,,,,thats good to know....It helps to know that others do this too...

I got some wire today and as I now have a bit more clay on the blade I thought it best to wrap the clay in wire as I have been also told a few guys do with Katana.
 
striper28 said:
Try warming it up with a torch in the area of the bend next time, .
Click to expand...

Ok, I thought about doing just that,,,However what stopped me was the idea Im shooting for a cool looking Hamon line. If I re-heated the blade in one area, dont I risk messing up the Hamon?
 
Jeez. I think I'd jump off a bridge if I put that much work into a sword and it cracked! Yikes! Can you turn the leftovers into anything decent? FWIW, I always coat the spine, too, when I clay heat treat, but the dynamics are MUCH different. I'm using 1084 in oil quench, with blades under 4" long, so it's a totally different situation.
 
well....the first one hurt my heart when it happened...it was like a child died in my arms.

But then I had a look at the broken ends and noticed that the grain was HUGE!

This points to an over-heated blade. Now this 2nd blade that cracked I was being foolish with and when I broke it I knew it would happen. I was working to get rid of a slight bend that just would not come out. I decided that I would crank just a little harder on it...I knew there was a big risk, but I really wanted the blade straight.
SNAP!

on the up side, I had a look at the snapped ends and the grain is tiny-tiny-small. So this made me feel better. I would never snap a Katana just to check out how my heating was, but now that it's done Im glad to see I have learned not to over heat the steel.

ANYWAY,,,I have the next Katana all wired up. this time I clay coated the whole spine. Another thing I did this time that is very different than what I did on the broken blades is that I did not grind down the spine area yet.

Before I always would grind down the spine so that after the heat-treatment there was nothing left to do there and I only needed to sharpen the cutting edge.

This time I will need to grind in later the whole spine and all the cool lines that are found on a Katana . My thinking is that the extra steel left on the spine, with the extra clay, with the wire wrapping, "SHOULD" help the blade become stronger and not want to snap later.
 
PS...

If this works tonight, if the blade lives past my heat-treatment and bending back to straight, then I will try to post a few photos in the morning. My wife will try to take one photo of my "Interupted Quench". I do a 2-part quench where I dunk in the water for 4 seconds, then lift out for 3 seconds, then dunk again.

The idea is an intrupted quench is going to cause less stress on the blade.

Oh, and its very cool to see the blade come out of the water the first time with a curve going the WRONG WAY!
and then once returned to the water I can watch and feel the blade spin around and curve the normal Katana-like way.

(oh and one more thing, if this next blad snaps, then if you are outside tonight you may hear a scream comming out of the north)
 
If it makes it across Lake Michigan I'll be worried! :) Good luck! Can't wait to see the pics tomorrow!
 
Reheat treating an already heat treated blade will cause an irregular hammon or water shadow. The clay should be built up to no less than 3/8ths thick and even better if it were 1/2 inch thick. If the blade warps again heat up the area of the warp to between a straw and brown color and straighten while the steel is hot, heating a block of steel or iron to red and placing the spine in the area of the warp letting the blade absorb the heat will work better than a direct flame and should preserve your temper line.
 
It'd be okay if he normalized the blade and re-HT'd, wouldn't it? I screwed up a tanto a couple years ago and just got around to fixing it recently with Laredo7mm's forge. We used molten salts to normalize the blade in three cycles, cleaned it up, clay coated it, and redid everything and the hamon was fine. But, that was oil-quenched 1084...
 
Ok,,,if I need to , I will heat up some type of other steel and set it against the spine before I bend back the blade
 
The problem I had was with a blade that was already heat-treated, but had a nasty bend to the side.

I snapped the blade doing a cold counter bend with the vise.

I didnt try to heat the blade itself because I didnt want to mess up the cool Hamon line.

However this next time tonight, I will try to heat the blade with anther pre-heated section of steel held on the spine for a while.

might help...
 
DaQo'tah Forge said:
The problem I had was with a blade that was already heat-treated, but had a nasty bend to the side.

I snapped the blade doing a cold counter bend with the vise.

I didnt try to heat the blade itself because I didnt want to mess up the cool Hamon line.

However this next time tonight, I will try to heat the blade with anther pre-heated section of steel held on the spine for a while.

might help...
Click to expand...
If you're bending it, you should be bending it just out of the quench, while it is still hot. If you let it cool down, even if you do bend it without snapping it, you're putting a huge amount of stress into the blade.
 
But, I have to temper out of the quench....right?

I have been told that I need to run the sword into the kitchen oven right from the quench tank, or else I have a huge problem later with stress too...

Now I did start working on the bends when the blade came out of the 300 kitchen oven, but due to the cold winter here, the sword was getting cold about half way out to the shop..

also,,,,I think, (im not sure),,,but I think the sword can still bend a little in the tempering right?.
 
Tradtionally japanese blades were not tenpered but left with a flint hard edge and a soft spine. if internal stress is a concern an hour or two at 300 will help relieve that but keep in mind if tradition is what you are after you are not trying to get the same sort of edge flex that you temper to on every day using knives.
 
crap, crap.,crap....

this time, the crack happened right in front of where the guard will,,,er,,would have gone.

The curve is huge, just the curve of my dreams. everything went as it should have,,,I was very happy,,,right up until the moment where my wife and I heard an underwater, "Ting"

The odd part is that the crak came at the point along the blade with little on no curve....the area also was covered in clay and wire...
 
crap crap crap.....Im in a bad mood.....crap crap.crap..

well......time to grab some steel,,,,draw on my boots and winter coat,,,,and head out into the snow to my shop,,,,

and start ALL OVER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!......crap.
 
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