Hot forging San Mai billets

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Jonathan BRG, Oct 13, 2020.

  1. Jonathan BRG

    Jonathan BRG

    19
    Oct 11, 2019
    I tried doing a search, but couldn’t find the answer I was looking for.

    I posted a while back, have since read a million threads, and wanted to ask a hundred thousand questions.....
    But I always feel like they are too complicated.

    I’m going to give this one a shot.

    I have bought a few billets from Dion Damascus, and a few more of Hitachi (3 layer) San Mai, and a S/S clad San Mai.
    I made a couple knives, they were cool. But....

    I’ve noticed some beautiful San Mai blades out there, and I’m wondering if there is a way I can “hot forge”(?) these billets to enhance the patterns.

    I’m a stock removal guy (for now).
    I have a small forge with single Mathewson burner (and an Evenheat LB27...if that means anything).

    I know absolutely nothing about blacksmithing.

    Do I just heat the billet to a certain temp and beat the hell out of it?

    Im assuming I would start with a thicker billet, and work it down close to my final blade thickness.....?

    Thanks in advance.
     
  2. weo

    weo KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Sep 21, 2014
    Yes, forging can/will change the pattern a bit. I'm assuming here that you are talking about using the forging to create a wavy san-mai pattern opposed to the straight lines that typically happen with stock removal of laminated steel.

    I'm not sure I'd ever recommend someone "beat the hell" out of it, but in the spirit intended, yes, that's all there is too it. . . Kind of...

    What I'd do if I were in your shoes is get a piece of mild steel the same size as your billet and practice on that first.
     
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  3. Jonathan BRG

    Jonathan BRG

    19
    Oct 11, 2019
    That’s exactly what I’m trying to do.

    Any nuanced advice on how to achieve the “wavy”, while maintaining the sanctity of the core, and the flatness of the billet?

    Any major pitfalls to beware of?

    (Yup.....I really do know that little about this.)

    I appreciate the help.
     
  4. weo

    weo KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Sep 21, 2014
    start watching videos on forging knives, san-mai if possible.
    I'd start here first. While what you want to do is pretty easy in principle, but a good looking san-mai blade is one of the hardest forgings to do. The trick is keeping the core in the center while forging, so you have to forge on both sides of the blade evenly.
    With not much knowledge on blacksmithing, the first question should probably be, what type of hammer were you planning on using?
    I'd also look into your local blacksmithing organization and get to know folks who are in your area.
     
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  5. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    I take a san-mai billet and forge out the bevels to make a very thick and uneven edge. I do it is a rather rough way, deliberately not trying to make it smooth. This disturbs the parallel layers of the billet so when it is ground the san-mai line is wavy. Sometimes I just work it as if I was making a ladder pattern along the edge ... which gives a more wavy edge.

    All work is done at the high side of forging heat, almost to welding heat. Probably around 2000°F
     
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  6. Jonathan BRG

    Jonathan BRG

    19
    Oct 11, 2019

    When you say “thick and uneven”, I’m assuming that I am trying to keep the billet generally “flat” over total length, but kind of “lumpy” along the bevel?

    I have some Hitachi White Paper at like 1.3” x .137”.
    I’m thinking of giving it a shot with one of those just to get started, and see what happens.

    As I’m forging, is there a practical way to keep an eye on the core?
    Any visual cues?

    Thanks...
     
  7. Josh Rider

    Josh Rider Stuff maker Knifemaker / Craftsman / Service Provider

    Sep 2, 2014
    I like the “if you’re going to be a bear, be a grizzly” attitude, but are you sure you want to try your first attempt at forging on San mai and hitachi white? That could make some expensive mistakes.
    Don’t get me wrong, I’ve done similar things, but looking back now, I would have tried on some inexpensive steel before moving on to expensive stuff.
     
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  8. Jonathan BRG

    Jonathan BRG

    19
    Oct 11, 2019
    I
    I always assumed I was more of a “failure is a fine teacher” and “I’m about as patient as a rabid wolverine” kinda guy,
    But I’m definitely going to use your phrasing from now on.

    I think I paid like $30 for the Hitachi.

    I bought like 4 billets, so I guess I have the advantage of repeatable results, or tweaking from the exact same starting point in my favor.

    What are the other options for buying San Mai?
    I’ve been able to get some CuMai from Dion Damascus, and some 410ss/52100 from Alpha, but I don’t recall them being far less expensive.

    I wish I could get bigger Hitachi billets, but I’m hoping that by forging these, I get the added benefit of a wider blank.
     
  9. Josh Rider

    Josh Rider Stuff maker Knifemaker / Craftsman / Service Provider

    Sep 2, 2014
    Well I’m just going off of what I recently paid for hitachi white. For 2 billets from dictum I was north of 100. San mai was about as expensive. My intention is never to dissuade anyone to do something they want to do, it’s just to try to save someone from wasting money. I forged some DHIII for some of my first forging projects and looking back I wish I would have waited. I have more, but a lot can go wrong while forging and especially while learning.
    Try not to overheat. It’s hard to do without experience and good temperature control.
    But if you do your due diligence and research, you’ll be happy in the end. I would just recommend trying with some simpler steels before moving on to the good stuff.
    At the end of the day, do what you want and make what you want and you’ll be happier with the results.
     
    Jonathan BRG likes this.
  10. Tenebr0s

    Tenebr0s

    386
    Jun 3, 2012
    The simplest way to achieve some wave in the core of sanmai would be to do some (don't go nuts) cold forging on the bevels of your blade blank before doing any grinding or heat treating.
     
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  11. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    The way to keep track of the core is to grind the edge flat every so often and dip it in the FC tank. This will show the core metal as a back stripe.

    In the forging, once you have disrupted the lower part of the billet where the transition between san-mai and edge metal will show ( to make the wavy look), forge the edge area only so the core is straight. Use the above FC dip to check areas you need to push left or right. Once the edge is showing as more-or-less straight, then you are ready to grind the bevels.

    Sometimes use a modified 1 pound ball peen hammer to put a row of dents down both sides of the blade where the transition will be. This will create a sort of wavy line, but leaves the edge pretty much undisturbed. The ball has been ground down to a very slight curvature face.


    TIP:
    When doing the grinding, dip in the FC tank regularly to keep the core centered and expose the hard metal evenly on both sides. Don't grind one bevel and then the othere ... go from side to side a little bit at a time. If you don't, it is easy to end up with one side having a 3/4" high ha (the hard metal edge) and the other barely showing the ha. The tip can also get way uneven if not ground slowly switching from side to side.
     
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  12. Tenebr0s

    Tenebr0s

    386
    Jun 3, 2012
    You could also grind some shallow scallops along the edge (don't grind into the core) and hot or cold forge the edge flat. This will change the proportions of core to cladding in regular intervals and give you a wavy look.
     
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  13. Kevin Kf knives

    Kevin Kf knives

    233
    Jul 2, 2018
    [​IMG]

    This is what I do to get a non-wavy line. Cut and or drill holes, heat, hit with hammer until close to flat again. I've lost the center of the san mai a couple of times. But I like the results. I wouldn't practice on one of his expensive billets at first
     
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  14. Hubert S.

    Hubert S.

    476
    Dec 14, 2019
    Do you happen to have a picture of the two knives after finishing?
     
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  15. Kevin Kf knives

    Kevin Kf knives

    233
    Jul 2, 2018
    This is just an example of what I was talking about, but here's a picture of one that i actually made using the same method. [​IMG]
     
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  16. Hubert S.

    Hubert S.

    476
    Dec 14, 2019
    Thank you for posting the picture. My first reaction was: This guy must be from Florida!

    I like the look your method creates and it seems like it might be doable even for somebody like me who does not know how to forge.

     
    Jonathan BRG likes this.
  17. Kevin Kf knives

    Kevin Kf knives

    233
    Jul 2, 2018
    Yup, Miami-Dade county here. If you look about an inch from the tip, I lost the center a little. But experiment with some cheaper san mia billets first, I really like the ding Damascus billets. Good dude
     
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