samurai swordsmith making fire

[hammock monkey]

caught a documentary on sky about the old world Japanese sword-smiths, great stuff, one thing that was quite interesting was the way the furnace was lit.
A piece of steel (cant remember the type) was lightly beaten over the anvil in such a way to heat it. Within 20 taps the end was glowing red and lit the tinder stick. I worked with a blacksmith years ago but I've never seen or heard of this before, it was a fantastic testament to their skill.

well worth keeping an eye out for, it was called 'the master' if your interested, on nat geo or somewhere near.

it made me wonder if its possible to re-create in a b/craft context...anyone tried?

 

[decorum]

From your description I'm assuming it was shown on the program and not just talked about. Are you sure they said it was steel? The only thing I can think of that might do the 'tap & glow' (compression and friction) thing is magnesium (or possibly an alloy).




General Disclaimer:
I am not a metallurgist. Magnesium is not the safest of materials and it is extremely dangerous to treat magnesium in this and other ways. Furthermore, I urge anyone who is interested in the general subject of this thread to seek an expert opinion on chemical reaction within metals.

 

[Tengu]

No use to me, even `I` dont carry a swordsmith along with me.

I always thought they used tinder or flint, or one of those new fangled lighters made from a pistol wheellock.

or carried a spill in from the kitchen....

Though I suspect some were so busy they didnt let the forge go out.

 

[Blankfisherman]

If it is the same one I saw a few years back I could not take my eyes from the box for over an hour - absolutely brilliant

 

[Mike Ameling]

Yes, you can heat up a piece of iron enough by hammering it to light a fire. I have done it, but it really can tire you out.

Every time you hit a piece of iron with a hammer, you are adding energy into it - converting force into heat. The faster and harder you hit it, the more "heat" you add into it. But you are also losing heat to the sorrounding air and anvil. So you have to add in enough extra energy to offset that loss, and eventually heat the iron up enough to be hot enough to start glowing red. You also have to balance the size of the iron piece you are hitting against how much of it needs to be heated up.

You take a piece of iron rod around 3/8 inches in diameter, and use a 2 1/2 to 3 1/2 pound hammer. You then start hammering the end of the rod on your anvil. You need to hammer fast and sort of hard. Hard accurate and fast blows. When you start to see some red color in the metal, it is hot enough to light some dry tinder - and there you have your "spark/ember". The rest is normal fire starting.

You can use a smaller diameter iron bar, but it starts to get more tricky balancing the force of your blows with what is happening to the iron. The end of your rod can start too split and break off instead of heating up enough.

I've done it, but it really wore me out. At least I had some time to rest as my forge was heating up.

Just another method of fire starting.

Mikey - yee ol' grumpy blacksmith out in the Hinterlands

 

[hammock monkey]

watched it again this morning, it was just iron bar, 10/12mm square beaten fairly lightly into a square taper. virtually bouncing the (as mentioned) 3ish lb hammer onto it, rotating it 90 degs to keep the shape, then flatter at the end as it glowed. Seemed to glow relatively easily...God knows how, i've worked with metal professionally for years and it just seems like the bloke had the magic touch...
maybe its why the show was called 'the master'

the blade contracting when quenched to give the main curve of the blade (katana shape) blew my tiny mind, genius.
both were done in front of the camera, else i'd have seriously doubted it personally.

 

[C_Claycomb]

Japanese smiths will bounce the blade they are forging so that it does not rest upon the anvil between blows. This takes quite a lot of skill, so that the steel touches the anvil just in time to be hit with the hammer, then as the hammer is lifted for the next blown the steel, or iron rod in this case, is lifted behind it. This keeps the heat in the workpiece.

For information, the curve that you get in a katana is not from the steel shrinking upon being quenched, it is due to the steel at the sword's edge expanding. This change of shape is not due to the shrinkage/expansion that people are familiar with when things get heated or cooled. Here is a pretty good explanation by Master Smith Kevin Cashen (posts on Blade Forums and Sword Forum)

I am not sure what the process’ and purposes are for other smith interrupted techniques, but here is what the concept is from a metallurgical point of view and why I would do it.
Austenite is FCC (face centered cubic) which is a most efficient atomic stacking arrangement. All the other transformation products that occur on cooling are BCC (body centered cubic)or body centered in nature like the BCT(body centered tetragonal) of martenensite, which takes much more space for the same amount of atoms. So while we do get simple thermal contraction as metal is cooled it is fairly small compared to the massive expansion you get when you have a BCC transformation. This all seems academic, but some folks may not realize this. I recently read an article that stated that steel contracts when martensite forms, this is so completely opposite of the facts that I was shocked the editors let it get by them, it is quite basic and fundamental that the martensite transformation is one of the most expansive.

So when you cool a blade and one part cools quicker than the other it will reach a body centered (hopefully martensite) transformation sooner. If this happens you could have expansion on one part of the blade while another is still contracting, it is obvious what the dangers of this may be, and since the part that has not yet transformed is still very plastic austenite, there is plenty of room for permanent shape change. If you interrupt the quench just before this transformation and allow the entire blade to equalize in temperature before continuing, it becomes very obvious how advantageous it can be to have the entire blade hardening evenly at the same time.

It is best done as near the transformation temperature as possible without beginning it. In oil I like to pull the blade out at the point where there is just a few wisps of vapor coming off the steel and the oil is able to coat the blade without burning off or flashing. Many oils have a vapor point that approximates 400F. so that can be helpful.

I have hade better luck with clay in oil by having a soft wooden block to tap the spine of the blade on and knock the clay off before allowing it to cool. When you are playing with clay you are dealing with a more complicated process, since the pearlite transformation will also be BCC and will have to be dealt with as you are intentionally making pearlite as well. The idea here is the same but a little trickier since you need to balance the martensite formation with the pearlite formation. Have you ever heard about folks complaining of a reverse curve when the quenched a clayed blade in oil? The pearlite formation got away from them and the tip dropped. I believe this phenomenon is very much more complicated but I need to have data to back my theories before I am comfortable sharing them. Anyhow the idea behind interrupting the quench in water or brine is to slow things down enough to even out the transformations before martensite runs away with the process and you hear that awful “ping”.

http://www.bladeforums.com/forums/showthread.php?t=357089

Not quite such a simple process as it can be made out to be

 

[Mike Ameling]

Oops, I said 3/8 inch rod, I should have said around a 1/4 inch rod. The smaller the piece of iron you are hammering, the easier it is to get that heat added into it. But the small you start with, the easier it is to mangle the end of the rod instead of getting it heated up.

Still a fun ... exercise ... in fire starting. Just plan on resting a bit afterwards - if you have not been conditioned to a lot of hammering.

There are so many things going on within iron/steel when you forge it to shape, and even more when you go to heat-treat it. The metal expands with heat, and then contracts when cooled. There are several very distinct crystaline grain structures in a blade based upon where it was and how fast it was cooled - all within the same blade. Pretty complex stuff. That's why it takes a while to really learn what is going on when you try to make a knife. Most anybody can make a "usable" knife, but to make a truly good one takes a lot of education and experience.

Heat-treating flint strikers is pretty easy compared to properly heat-treating a knife blade. That's why I stay away from making anything other than simple knifes.

Just some humble thoughts to share. Take them as such.

Mikey - yee ol' grumpy blacksmith out in the Hinterlands

 

[hammock monkey]

Japanese smiths will bounce the blade they are forging so that it does not rest upon the anvil between blows. This takes quite a lot of skill, so that the steel touches the anvil just in time to be hit with the hammer, then as the hammer is lifted for the next blown the steel, or iron rod in this case, is lifted behind it. This keeps the heat in the workpiece.

For information, the curve that you get in a katana is not from the steel shrinking upon being quenched, it is due to the steel at the sword's edge expanding. This change of shape is not due to the shrinkage/expansion that people are familiar with when things get heated or cooled. Here is a pretty good explanation by Master Smith Kevin Cashen (posts on Blade Forums and Sword Forum)



http://www.bladeforums.com/forums/showthread.php?t=357089

Not quite such a simple process as it can be made out to be

interesting, they actually managed to show the blade entering the water and bending backwards as it cooled - which cant be the easiest shot to make, but you could see the blades curve developing, so it was fairly believable yet unbelievable/ amazing. I've got it on sky+ so i'll re-watch and see if i misunderstood.
Look out for it, its great viewing.

 

[climberslacker]

In geography class we watched this video of this guy who was supposedly able to start fire with his mind, he rolled up a newspaper and then waited a few seconds with his hand over the newspaper and it lit! We watched it like 4 times in a row, it was amazing!