THE TANEGASHIMA BREACH PLUG ( BISEN ) ADDENUM

[watsonmil]

Dear All,

First refer to past thread : viewtopic.php?f=87&t=19589&start=0 Some new ( to me new at least ) which confirms my theory that many of the Threads on the Tanegashima were FORGED rather than cut. Only the male thread ( bizen ) threads were cut by hand filing. Please see :

https://www.jstage.jst.go.jp/article/te ... 6/_article.

 

I quote : " The metallurgical macro- and micro-structure, and the residualstress of the Japanese matchlock gun, fabricated at the late Edo period, have been investigated with an optical microscope, an SEM, an EPMA and an X-ray residual stress meter for estimating the fabricating process and their materials. This gun was fabricated by Udonbari (in Japanese) process, which is similar to that of the Russell's method, tubes was created by the joining together opposite edges of a flat iron strip with an iron core bar. The joining line was wavy. Their residual stress was mainly compressive and the values were from 180 to 280 MPa in the longitudinal direction and from 240 to 380 MPa at the transverse direction.

The gun was made of low carbon steel with equiaxed ferrite grains; their grain size was mainly 10 μm partly with 100 μm and exceptionally more than 1000 μm grains. Moreover, we find the special banded structure, consisted of fine ferrite grains bands and large ferrite grains bands.

The firing part was fabricated by the joining of five parts for getting the L-shape hole. The female screw was made by forging; therefore the shape was tapered screw and the male screw was cut from a low grade steel bar, confirmed by their macro-structure. "

 

... Ron Watson

[Brian]

Good find Ron.

Pity it's in Japanese. Anyone want to investigate sharing the costs of a translation by Markus? Crowdfund project?

 

Brian

 

Edit to add: A few more related articles

https://www.jstage.jst.go.jp/article/ji ... 0_778/_pdf

https://www.jstage.jst.go.jp/article/ji ... 4_250/_pdf

https://www.jstage.jst.go.jp/article/ji ... 6_489/_pdf

[DanC]

Ron,

 

Looks like you've made good progress on your research. Come across anything about whether the final breach plug itself was used as the die while forging the barrel threads, or if the final plug was cut to match a disposable die used during forging?

 

- I could probably chip in some to a translation.

[watsonmil]

Dear Dan c,

Since the die thread used in the forging of the barrel was HARD steel, ... and the Bizen was of soft steel, ... it would be only logical that the threads on the bizen were hand filed to match the threads of the male die. The male die was probably reused numerous times in other barrel making. See: in the first part of the addendum : " The female screw was made by forging; therefore the shape was tapered screw and the male screw was cut from a low grade steel bar, confirmed by their macro-structure. "

 

 

... Ron Watson