View Full Version : Some san mai and experiments WIP

10-28-2011, 03:25 PM
A little Wip for some techniques I have picked up in san mai. And an experiment in 01/damascus to make a blade for testing and comparison.:D

First making some simple damascus in 75ni8/en42J
The billet welded up, I now use the fullers in the power hammer to manipulate the layers, a sort of forged ladder effect, there is a thickening and thinning of the layers that remains after flattening.
Cut to 4 and restack, back in the fire.
Some slightly sharper fuller tools
Can see the cool grain in the damascus
Damascus billet
San mai'd with mild steel. The ratio is important, depending on how close you want the san mai, the type of grind etc. The mild will thin quicker than the core and this needs to be allowed for.
I fullered the san mai together as well, to achieve a ripple effect on the weld line.
Plenty of stock, quite an efficient use of damascus.
Ratio after forging
I got an extra one out of the left over damascus too. This one had the damascus as the cladding and 01 in the middle. I've been looking at the temper temperatures and I think these will work well together. At a 200*c temper I should have something like 62hrc on the core and 52ish hrc on the damascus cladding. Sounds good to me:D

10-28-2011, 05:02 PM
I was waiting for the wip to appear over here :D

Are the sharper fullers a new addition?

Eamon Burke
10-28-2011, 05:09 PM

10-28-2011, 05:20 PM
Can't wait to see it etched. You sir get the cool WIP seal of approval.


10-28-2011, 05:30 PM
Thanks Guys, san mai is fun, but frustrating when you get it wrong. I think its particularly hard for shallower grinds, because there is such a fine line between it looking good or appearing overground in places, i.e. too much core showing. I'm still not sure how san mai works for single bevel knives? Is the carbon steel just on one side only, if so that must be very hard to keep straight on ht.
Tom, those fuller are fairly similar to the fixed hammer ones really, I made them to have a more quick change system, for fullering then flatting. Nothing really beats the control of having the fixed ones in the hammer though if precision fullering is the aim. I've made a few handy quick change tools specific to knife making now, one for drawing the tang also. I might have to get some fixed die's machined like the Japanese hammers have soon, with a large die on the bottom, smaller on the top, for tapering thinning the blade and drawing the tang.

10-28-2011, 05:51 PM
You are really moving, Will! I love it when a WIP teaches me something.

10-28-2011, 06:04 PM
The amount i've learnt from you guys on here, its a pleasure to share some stuff about forging.:biggrin:

Dave Martell
10-29-2011, 09:11 PM
Very cool WIP again Will - thanks!

10-30-2011, 07:48 AM
Lol, drawing out the tang on your anyang is a fun eperience :D

Yeah single bevel knives only have the hardening steel (Hagane) on one side

Vid below show's Doi forging one out


10-31-2011, 12:59 PM
Cheers Tom, yep I think he's done that a few times:D
Had a play with the test 01/san mai billet today. Was going to be a Gyuto, but changed my mind and did another Suji.:D
HT'd and ground, very much a test knife this so I fully convexed the faces, see if I like it better. The san mai was only just big enough, It was an effort to get it to hit the edge in places:sad0: But i'm pleased with the way it is nice and close and supportive to the core, with a nice wiggle from the fullers.
Terrible light today, but here are some pics. Its rough ground and etched. I'm just about to hone it up to see what it can do before any hand rubbing. The tip is super pointy, plenty of room for adjustment though.
Here's the result of the damascus cored San mai

10-31-2011, 01:23 PM
That is so cool man nice work

10-31-2011, 02:23 PM
A word of caution on the mild over damascus. In thin sections carbon migration will occur from the high carbon damascus to the mild steel, it is just a matter of to whay extent. You could end up with the steel equivalent all the way through the biullet of approx 1050 or 1060 if you are not carefull.

10-31-2011, 02:43 PM
Looks really good. Emoto/neck looks much shorter than the passaround and should be much more comfy. Profile looks much better, tip looks cool. And the san mai looks good as well, thanks for the WIP. Nice work!

10-31-2011, 04:27 PM
Thanks Guys.
Carbon migration is a good point and something i'm very aware of in san mai. Interestingly you can see the carbon which has leeched out when you polish against the grain with an edm stone. I expect finger stones would be great to bring this out as an additional effect above the san mai. Short of using a slice of nickel on the weld line, I accept a little carbon loss as part of the deal. All though a little migration is clearly happening at the weld line, I have never noticed any loss of hardness, performance of the steel, I have made allot of san mai blades, some in steel which only had 0.5%C in the first place. I believe this is because, I am not repeatedly overheating the billet, using a power hammer helps most here, that and good temperature control, grinding after HT helps prevent any additional carbon loss.
I suspect the main candidates for excessive carbon loss are, poor temperature control, especially in a coke forge, and taking repeated forge welding heats.
The bonus of san mai is that you can take the core steel harder and get away with it in terms of flex, (if you have enough carbon left):laugh: The core in the mild/damascus was testing a tad over 60hrc with a hardness file, so I know there was no excessive carbon loss in this case. It is a bit of a juggling act though, between core thickness vs decarb vs edge support from soft steel, but thats why its such fun.:D

10-31-2011, 04:33 PM
Carbon diffusion occurs very quickly because it's a very small interstitial atom in iron. Be careful in assuming it's not diffusing.

HHH Knives
10-31-2011, 04:49 PM
Those are awesome! i love the look of damascus cored san mai great work man.
-Randy Jr (forgot to log into my account :D)

10-31-2011, 04:52 PM
I'm not assuming it isn't:D, there's no stopping it, apart from a barrier of nickel or an equal balance of carbon. I'm assuming that it is, and minimizing it as much as possible.
Thanks Jr:biggrin:

11-01-2011, 09:11 AM
I figured you knew but just threw it out there for a discussion point. Keep up the great work!