Author Topic: CuMai  (Read 803 times)

Offline KenH

  • Top Active Citizen
  • *
  • Posts: 112
  • Liked:
  • Likes Given: 115
CuMai
« on: January 29, 2022, 11:25:45 AM »
I've not posted any knives I made lately.  This is my first attempts at CuMai.
I've always been impressed with the copper line in the blade and wanted to try one myself. I did this one with a .070" of 26C3 core, a .030" layer of copper on each side, with a 3/16" of 1075 on each side. After forging and shaping I got this skinner. It's still a bit rough in the ricasso area. It seems the tong hole is popular so I added a bit of paracord with mammoth ivory button.

It's forged around 1850F to stay below the melting point of copper. The copper acts as a bonding (soldering?) agent between the two layers of steel.
The billet for that knife was pretty thick with 2 layers of 3/16", a .070", and 2 layers of .030". Knowing it would have to be drawn out I seal welded all the way around, just like San Mai with SS cladding. I did the work in the forge while trying to hold temp around the 1850°F range to prevent melting the copper.

The next I did was with a thinner billet, .040" core of 26C3, .010" copper on each side, and .062" of 410 SS cladding.This I wrapped in SS foil and heated in oven at 1850°F. I figured the oven would help hold the temp more accurately than I could in the forge. Using a 4" flat die in the 16 ton press I just squeezed the foil packet. The first billet done this way I used the drawing dies to to get the billet thinner for kitchen knife, trying to .090 or less. It looked like I did a bit too much pressing and the thin copper didn't like that.

So, next billet I just pressed with 16 tons using only full flat die. This blade is the result. After squeezing I expect the core and copper might only be in the .050" thick range, I used the SGA to grind the SS so the final thickness is in the .090" range for the final blade. Still a tad thicker than I like for small kitchen knives, but they work pretty good - and the wife LOVES her some copper  At .090" with a .050" core/copper thickness that only .020" on each side causing more of the 26C3 core to be exposed than I wished. Especially on this side.

and more copper than I wished on this side:

 think my next attempt will use the drawing die, but gently so it doesn't squeeze quiet so much, but still give a wavy line to the copper.

 

SMF spam blocked by CleanTalk

© 1995 - 2022 CAScity.com