San mai ladder damascus question

[John_Keating]

I made a billet of crushed w’s and laminated a core of 26c3 in it. My starting stock was basically 1/3, 1/3, 1/3. I forged it down to .3” and preformed my tip. I plan on cutting the ladder in then forging flat. The issue I have now is making sure the core sits center of the edge after cutting and forging back to flat. I’m thinking of stopping the cuts short of the edge so I can guarantee my edge is all 26c3.

In hindsight I would have made the center core a little thicker to make up for the ladder cuts, also seems that 26c3 moves much faster than my pattern welded steel. A quick etch of an off cut shows me that the core is closer to a 1/4 of the overall thickness of the billet.

Any tips or tricks I could try?

 

[MSicardCutlery]

If the cuts are dead even, that is-lined up perfectly between the two sides, the core should stay centered if your forging is also even. However, you might have been better off doing all the pattern development first, then making the san-mai.

 

[John_Keating]

If the cuts are dead even, that is-lined up perfectly between the two sides, the core should stay centered if your forging is also even. However, you might have been better off doing all the pattern development first, then making the san-mai.

Didn’t think about doing the laddering first. T might wash out the ladder effect after drawing the billet out though.

Either way I’ll do something about it tomorrow and post up the effort.

 

[John_Keating]

Well, forge out a small chef type knife. Things went ok but I think the core steel was too thick. I forged the knife pretty darn thin, almost as thin as a mono steel blade and my core appears to be about 75% of the visible steel at the edge of the profile. On the bevels the pattern looks great but I’m afraid if I go as thin as I wanted to on this knife all I’ll have is core steel dotted with damascus cladding. Forging another small chef knife just with the cladding next. My wife needs a birthday present and time is growing short.

 

[John_Keating]

If the cuts are dead even, that is-lined up perfectly between the two sides, the core should stay centered if your forging is also even. However, you might have been better off doing all the pattern development first, then making the san-mai.

Do you mind describing your process to do that? I can’t figure out how to take that approach without distorting my ladder pattern in the process.

 

[MSicardCutlery]

How you can do it is highly dependent on your equipment. What do you have to forge it with? A mill? Press? Hand hammer? You will get some distortion with every method, but it will be minimal with a rolling mill, and fairly controllable with a power hammer.

You're in a bit of a bind because of the geometry required with kitchen knives. Thicker knives are much easier, and ladder pattern is not the easiest place to start. Your margin for error is about as low as it gets in the knife world.

If you have no forging equipment I would try to start with as thin of core material as possible, do all the pattern development before hand, then laminate everything and draw to a minimum. Be mindful of how the pattern will elongate as it's drawn out. Alternatively you could give warikomi a shot.

Chamfering a san-mai billet at the edge to the core will also help keep the core centered, but things may still be out of center further up from the edge.

When I make san-mai with soft cladding, I tend to make the cladding in the final billet twice as thick as the core on each side. A larger billet retains heat longer, and it give you a greater margin for error.

I've recently made some wrought clad san-mai and in places the core steel is only ~.003"-.005" thick. You can go really really thin so long as your forging is even.

 

[John_Keating]

Great info, thank you.

I have a press and the rest is hand hammering. Last couple of San mai I’ve done has all been 1/3 core but for thicker knives. My thought was for a kitchen knife I’d just forge thinner and all would be fine.

I should have been more specific of the distortion I wanted to stay away from, mostly stretching the pattern out too far. I don’t expect perfection considering I’m hand hammering, a lot of it is to improve my technique and a core makes my mistakes easy to study.

I cut the ladder a couple of different ways. The first knife I ground with an abrasive wheel then leveled the cuts with a file. Being smarter the next go around on the second knife I used a 3/8 round wheel and set the spacing so the left over material came to almost an edge, the pattern looks much closer to what I wanted vs the san mai knife.

 

[John_Keating]

Decided to start grinding on the second knife I laddered yesterday. It’s 15n20/1084, 62-62.5hrc. I just got done finalizing the geometry and test cutting with it, I think it will be a good tool.

The ladder pattern will need to be an ongoing adventure. Lots of options for distortion and even with not great hammer control the pattern is still interesting and not overly upset from drawing it down after laddering. I haven’t seen the bevels yet since setting the geometry, hoping the pattern is as interesting as it was in the test etch.

I’ll follow up with it later after I get it finished, will be a couple of weeks as the fam has some time off coming up.