stainless san-mai

Daniel Koster

Daniel Koster

www.kosterknives.com
Knifemaker / Craftsman / Service Provider
Joined
Oct 18, 2001
Messages
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Does anybody have any information on making stainless san mai? (carbon steel between 2 layers of stainless)
 
You can weld all kinds of things in a can.

I'll post some pics next week if I get time, busy trying to get moved this week.

Tony
 
I never understood why anyone would mix carbon and stainless.You woul;d have to take care of the carbon anyway to prevent rust.I have a Helle knife that is all stainless laminate and the Shun knife all stainless with damascus outside .I'm very happy with both.
 
simple - with a carbon core, you just let the small bit of carbon naturally tarnish, while the rest of the blade stays shiny. Even better if it started out that way at first.
 
Where can I get this stuff?

- 3 Parts Borax (anhydrous, dry powder) **got this already**
- 2 Parts Boric Acid (Powder)
- 1 Part Ammonium Chloride (Powder)
 
The boric acid can prolly be found at walmart. Some people use it as a roach poison.

What are you going to do with that mixture?
 
that was suggested in that link I posted from Don Fogg's forum - as a better mixture for flux, vs. plain ole borax.
 
I add either the boric acid, (yes it IS roach powder) or flourite. flourite is my personal preference, but I really think it's a personal thing... with flourite, I only add about one part to 25 of the borax, and the flux is so strong, I can forge weld stainless open in coal. (yeah, I said *most people* do it in a can :) )

I'd still recomend the can though, less to go wrong that way

Tony
 
I recommend that you use 400 series stainless; the 300 series has a heat treat like non-ferrous and makes it very difficult or impossible to anneal. A thin nickel sheet on either side of the core will insure success.
 
Thanks for the excellent suggestions and tips, guys.


What about something like this?

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Just thinking out loud....would it be better to forge the blade slightly to shape, grind it clean, and then laminate? Would that help the "shift" problem you get? (the carbon steel not staying in the true center)



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I know that it's probably easier to just do it like this:

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But I'd like to keep the stainless on the spine if possible.

What do you guys think?
 
A similar process is where clad is hot cut and the high Carbon is inserted and forgewelded as a core. In laying up a San Mai you can have two strips of steel in the core, one for the edge and one for the back of the blade. The two parallel strips are the core. You can weld with mig or tig the two strips together then surface grind to form your core. I've also welded a 52100 rod into a piece of stainless pipe. Forge flat and split the billet lengthwise, or trim one edge. There are many techniques for making cored steel. You can mig the outside of the billet edges and create an anerobic encasement to elimninate the box or flux. Most all of my cored steel is dry welded. Be careful it may be impossible to make anything but San Mai. I trimmed a billet of 15N-20 with a 52100 core. I bent a strip of this material in the annealled state. I got 40 180 degree bends before the core crystalized and the billet broke. The increase in strenght of a San Mai Mosaic billet over Mosaic Loaf material is huge, maybe a multiple of ten in breaking strength. San Mai margins of improvement are very very large and well worth pursueing...Take Care...Ed
 
very interesting information you posted there, Ed.

When you put the 52100 rod in the stainless pipe, was there any air gap? What do you do about it?
 
I bored the weld seam out of the pipe and had a fairly tight fit. I sprayed the 52100 with WD 40 and rolled the bar in nickel powder then drove it into the stainless pipe. The pipe I was using was 304 SS and not appropriate for this project. 400 series pipe wopuld be good if you can find it...Ed
 
The rod in pipe technique has to be credited to the Japanese. They used this method to produce military swords when high Carbon Steel was becoming rare at the end of WWII.
 
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