japanese brass/bronze springs

[mattybock]

I used to be into japanese cartoons when i was younger and one of the big aspects of those cartoons was old world japan. Samuria, ninjas, men in poofy pantaloons. All kinds of neat junk.
Swords were the big selling point. Every teenager wants a sword, but as I got older I read deeper into this stuff.
Turns out that the real samurai were more of less hired thugs who relied on the matchlock musket to to the muscle work of the feudal lords who hired them... guns! who knew!
Well most of these matchlocks had brass or bronze springs, iron being hard to find. And I'm wondering - how are bronze springs even made? Does bronze just hard that much natural springiness, or where they tempered or what?

 

[jdkerstetter]

Um? Iron hard to find in Japan? How do you explain all of those swords? Certainly takes more iron to make a sword than a spring for a gun. :shake:

Enjoy, J.D.

 

[jdkerstetter]

.....anyway, for what it's worth, the springs on these weapons were very weak as all they had to do was lower the match into the prime. Unlike the caplock or flintlock, no force was required for ignition.

Brass and bronze do not make acceptable springs for most applications. Brass will work harden and snap and bronze is to brittle to start. For the low tension and small stroke required for these matchlocks they were apparently addequate.

Enjoy, J.D.

 

[Rod Lassey]

Um? Iron hard to find in Japan? How do you explain all of those swords? Certainly takes more iron to make a sword than a spring for a gun. :shake:

Enjoy, J.D.

I had always heard that iron was fairly scarce in Japan--they didn't waste it on horse shoes, for instance--but your comment got me curious. A little bit of Googling and I found that iron in Japan is primarily found in just one province, and in an iron sand form. Other than that, they tended to import alot, some from Korea and northern China, both of which were under Japanese control off and on throughout history.

Anyway, for you metallurgists, I found this site pretty interesting (has nothing to do with guns, though). Everything you'd want to know about hardening and tempering the steel in swords.
http://www.shibuiswords.com/tatsuoinoue.htm

Funny the tangents these threads will go off to, isn't it? :wink:

Rod

 

[Zonie]

Both brass and some kinds of bronze can be used as a spring. Most bronze's are too brittle to be used as a spring though.

Materials like brass with a lot of copper in them cannot be heat treated to make it hard and springy but it can be hardened by bending it or hammering it while it is cool. Running it thru rollers to reduce its thickness will also work harden it as does expanding it with dies.

The catch is there are hundreds of different brasses and bronzes and not all of them will make a good spring.

Even those brass or bronze materials that do make good springs are comparatively weak compared with a steel spring because for a given thickness they bend more easily (their modulus of elasticity is lower).

 

[RR_Raptor65]

Um? Iron hard to find in Japan? How do you explain all of those swords? Certainly takes more iron to make a sword than a spring for a gun. :shake:

Enjoy, J.D.

Iron weapons were relatively rare and expensive, iron body armour is practically unheard of. Body armour was typically made of rawhide coated in lacquer.

The usual way for the Japanese to get iron was to build a bloomery and melt down iron rich sand.

[youtube]W6uFAv9L734[/youtube] [youtube]gDy1jx6mLgs[/youtube]

The brass springs of a Japanese Matchlock were hammered into shape, the hammering being what gives them the hardness to work as a spring, though not nearly as powerful as the steel springs we're used to in other BP guns they only need to be strong enough to move the match to the pan.

You'll also notice that the springs are very long as this helps prevent rapid work hardening, they also have low compression, that is the end of the spring doesn't have move very far when the serpentine is locked.
The shape in general is similar to the idea behind the shape of a bow, it's purpose is to create a smooth even bend, not allowing one part of the spring to bend more than the rest where failure will eventually occur. This is true of many flat springs but in brass it is especially important.

I have never had the pleasure of working bronze though I am told when heated it is like putty, I expect it would need to be worked like brass to create a spring.

 

[jdkerstetter]

Um? Iron hard to find in Japan? How do you explain all of those swords? Certainly takes more iron to make a sword than a spring for a gun. :shake:

Enjoy, J.D.

:haha: :haha: :haha: Glad this post gave you all something to jump on. Facts are facts though. Whether imported or not, there was enough iron in Japan to fashion thousands of swords and various other edged weapons. They simply chose not to use it for armour, horse shoes and springs. :wink:

Enjoy, J.D.

 

[ChrisPer]

Ironmaking in Japan was advanced but small scale and high cost. The ironsand was magnetite sand, probably washed out of river-sand with sluice boxes - ie water-borne density separation. These days such material is separated magnetically.

Great chapter on ironmaking in Yoshindo Yoshihara 'The Craft of the Japanese Sword' - highly recommended.

 

[mattybock]

one thing about iron smelting... making (?) in japan was the funky furnace they used. It wasn't a tall cylinder blast furnace like with europe and north america. They were short and box shaped. Instead of molten iron dripping out from a hole in the bottom, it all clumped together in wads throughout the big blocky furnace and at the end of the day they actually broke the entire furnace apart to pick out the little bits of clumped cast iron.
I'm guessing that maybe that shape had something to do with the efficiency of iron making. But that's just a guess.
PBS has a special about sword making in Japan and I was mesmerized by it.