Go Mai skinner

[Dave Armour 38]

Latest one of the bench. 5” recurve skinner. Blade is Go Mai mild steel outside/W2 core/nickel & copper in between. Wrought iron guard with stabilized claro walnut. As I play with adding nickel and/or copper to the mix I’m coming to realize I like one or the other. If I mix both it just looks “off”. Thanks for looking. 
 

[billyO 222]

Looks good.  I'd like to learn how to add copper into my forge welding. 

Is that some nickel/copper on the edge towards the tip, though?  

[Dave Armour 38]

24 minutes ago, billyO said:

Looks good.  I'd like to learn how to add copper into my forge welding. 

Is that some nickel/copper on the edge towards the tip, though?  

There’s a couple YouTube videos (they call it CuMai)that explain it well. Basically the top workable fusing temp of copper is right at the bottom temp for bonding nickel. Pretty straightforward but tricky to control the temp. I went to welding the seems closed like you would with stainless San Mai. That way you don’t have molten copper flying if you overshoot the heat.  Yep- there is one spot where there is nickel on the edge. I’m keeping this one for me, so I’ll live with it till it annoys me to the point I regrind to fix it. 

Edited January 16 by Dave Armour

[billyO 222]

Thanks for the info, Dave.  I might have to try that someday.  

14 hours ago, Dave Armour said:

Pretty straightforward but tricky to control the temp.

My PID controlled forge should help with that....

 

14 hours ago, Dave Armour said:

I went to welding the seems closed like you would with stainless San Mai.

Did you use a TIG welder for this?

[Dave Armour 38]

billyO-tig would work better, but I just have a cheap wire welder. One of the videos talked about problems with the welds because of the copper. So I would make sure the copper is slightly narrower than the steel not sticking out of the edges. 

[Bob Ouellette 65]

Did you do any forging after you welded it or is it strictly stock removal after that?

[Dave Armour 38]

52 minutes ago, Bob Ouellette said:

Did you do any forging after you welded it or is it strictly stock removal after that?

I drew out the point and tang somewhat. More to make sure the billet is solid rather than forging to any particular shape. I didn’t do any forging on the bevels. 

[Gerhard Gerber 353]

These CuMai videos showed up in my feed, been about a week of thinking how I'm going to go about trying this....

[Alan Longmire 2,746]

You just have to remember that at the copper it's not a weld, it's brazing.  Intergranular adhesion rather than diffusion bonding.  Forge at your own risk, and keep the copper away from the edge.  

 

Note that brazed joints are just as strong as arc welded joints (~60-80Kpsi tensile depending on composition), so no worries about it breaking that way.  The "intergranular" part means there is a risk of cracking, though. Of course, cracking in the quench is always a possibility with any steel combo.  Adding copper or brass just ups the risk a little.

[Dave Armour 38]

Thanks Alan for explaining it a heck of a lot better than I could have. 

[Bruno 89]

That's cool!    Now i gotta try that.   What's a good source for copper and nickle?

[Gerhard Gerber 353]

I'd like some opinions on whether my POA will work.....

 

I have 40mm wide by 3mm thick 1070, 25mm by 3mm thick copper bus bar.

1070 in the middle, then copper and I planned on hammering the overhanging 1070 bits of the outside layers to touch the middle layer, then seal up with the arc welder.