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Punch shear optimal geometry?


J.Leon_Szesny

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In japanese toolsmithing they got a type of cold shear setup but as usual details are lacking.

All I know is, the smith places a small plate on the anvil and his helper positions a flat looking punch over the edge of the plate, then the punch is struck, it makes a "plunk" sound and the steel placed between is sheared off clean.

 

I got 4 ideas how the details might look and considering that the force comes straight from the top, I'd be leaning to number 4 being "it"

But will appreciate a second opinion on steel shearing.

IMG_20220223_003749.jpg

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15 hours ago, Gerald Boggs said:

While lever actioned, both Mark Aspery and Brian Brazeal show a simple shear that attaches to the anvil stand.

can't find reference examples to marks and Brian's shears but the japanese style I'm going for ain't got a pivot(and probably not for lack of them being able to make it), besides most blacksmith shears I've seen can only cut 2-3mm thick things.

 

the japanese setup can cut 6-8mm thick in 1-3 strikes.

and it's a clean straight cut along an entire 7-10cm long piece 

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I've seen Mark cut cold 3/8 by 1 inch on his.  Looking in his book, he calls it a guillotine.  It's something that's been around for a while, Mark and Brian are just two folks I know who have posted photos of it on the web.

Edited by Gerald Boggs
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On 2/23/2022 at 6:48 PM, Alan Longmire said:

Got a link or picture of one?  Is the plate cut hot, cold, or warm?  "Warm" steel, at between 380-480 C (~700-900 F) shears more cleanly than glowing hot or cold.

I got a link to a blurry zoomed out recording...

I'll dig it up later but yes I think the steel might've been 300-400 C.

it definitely wasn't red hot

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