drawing out steel for san mai gyuto

[timos-]

Hey all,

I have a bar of san mai, a w-2 core with some a203e cladding. I purchased the forged billet and had it surface ground afterwards to make things easier on myself. Well, After removing the scale the 2" wide bar is now closer to 1-3/4 wide. Trouble is I need the full 2" for my project.
This is going to be a 210 mm gyuto and the heel needs to be a full 52 mm, thats just a hair or two over 2" wide. Soo, I am wondering if it is possible for me to draw out the heel/ blade at all with the bare minimum of equipment, torch and hammer....?

 

[Stacy E. Apelt - Bladesmith]

Normally, you draw down the edge by forging anyway...so you are right where you want to be. Pull it down to a tad past your needed width to allow for filing and sanding. By removing the extra metal in shaping the bevels, you will expose the core and create the contrast line of the san-mai. Forging down the edge allows this line to meander a bit and can look somewhat hamon-like at times.

That said, I would not attempt it without a forge, good drawing hammer, anvil that is reasonably flat, and some practiced forging skills. Why don't you visit a local smith, or send it over to one, and have him draw it out about 3/8" more .

 

[timos-]

Stacy,

The core is about .08 thick with almost .03 cladding on each side. It the edge was to be drawn out how would the pressure affect the different steels? Would the soft cladding give way or would it be drawn out thinner along with the core? Would it make sense to profile the blade and then draw it out or draw out the whole bar?

 

[Stacy E. Apelt - Bladesmith]

With .08" core and 1/8" total thickness, I don't see any problem at all extending the edge down 3/8".

Both steels will draw the same if the temperature is high enough. I would work a billet like yours starting at 2100F and quit after it drops to 1600-1700F. At these heats both should draw about equally. Any laminated billet should be worked at near welding heat to avoid delamination. ( This is why the torch and hammer would be really bad)

The cladding will get ground away on the lower portion anyway, so the amount of thinning there is insignificant.

On your billet, I would work the lower half only. Leave the upper area alone since it is already surface ground.