Average amount of damascus billet tip sacrificed???

weo

weo

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Sep 21, 2014
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Hello all, hope the end of spring finds everyone well.

I imagine there are many variables that will effect the outcome, so here's what I did:

Starting billet: 22 layers (alternating 6" long layers of .072 15N20 and .070 1095) clamped, handle welded on and one bead ran down the end of the billet. Forge welded, drew out, cut into 4 pieces, re-tacked and repeated 2 times to end up with 352(-) layers. BTW - all surfaces were ground clean before re-welding, and after the initial billet weld, I drew the tip out too much being the first time I've used my friend's 250# Chambersburg so had to lose 3" of material before the second weld.
Anyway, I ended up with a billet, 1 1/8" x 1/2" x 18". I cut off an inch of the tip polished and etched and the result wasn't what I expected, I took pictures and was going to ask what happened when I realized what I was seeing was most likely the 3 tack welds. I cut another 1/2" off and repeated the polishing/etching and am seeing the same strange pattern. I figured I should see pretty flat layers because all the work was done on the 5" x 7" flat dies, but there's a butterfly pattern.
I was planning on continuing to cut 1/4" slices off the end of the bar for another inch or so before cutting the grooves for a ladder pattern as per the original plan.
Any ideas on how much of the tip I should plan on loosing due to the tack welds of the 4 pieces? (Final billet size before final forge weld/drawing was approx. 5"x 1 1/2" x 2")

thanks
 
Butterfly pattern? Did you forget which was was up and accidentally do crushed W's? Welding rod would be ugly grey if you etched it.
 
Yeah hard to figure out what you're describing here without a picture.. You could have changed orientation if it looks like you've got "C"s or "S" shaped layers.


If on the otherhand instead of flat lines you've got flat lines in the center and curved lines on either top or bottom, it's likely that you dished out the billet when grinding (assuming you were grinding the scale off with an angle grinder). Or if you overworked the sides.


Using a big hammer like that moves metal very differently than a smaller hammer or a press. A combination of press and hammer is ideal to move metal consistently on the inner and outer layers.


FWIW that's not a very big billet for that size hammer, so you'll have to be cautious "getting after it".



One thing I think is a bit of a fallacy, especially when just starting to make damascus is thinking that "you're in control" of how the pattern moves. Yes you are, but it's a *MUCH* more complex combination of factors going on in any one heat. Fighting for homogeneity until you've developed the three dimensional thinking necessary, and experienced the myriad of variables, is simply masochistic. Play, have fun with the results, without expecting you know exactly what they'll be. Later, you'll start to really understand more of the interplay, and have ideas for pattern development. You'll still be constantly surprised at the results. If that's not something you can deal with, I suggest you pick another hobby. ;)


Personally I think this desire for control is why I see some makers that spend decades trying to "perfect" ladder patterns, and never end up making anything else.


Woops, I ranted. Sorry. ;)
 
Also, as far as losing material on the tip or handle end, that's another factor that you learn more about as time goes on.


Some mosaics/end grain patterns I do have up to 70% material loss ultimately, once you factor in end losses, scale removal, saw kerf, and final grinding to dimension. That's one reason why damascus is so expensive, and why many large suppliers only do side grain/pressed/machined patterns, or powdered mosaics.


Utilizing both a hammer and press can really help to reduce those losses by avoiding fishmouthing or swelling the tip. A hammer tends to fishmouth more as it moves the outside of the billet more (although the bigger the hammer relative to the billet size, the less this is an issue), where-as a press tends to cool the outside from contact with the dies and move the inside layers much more, which can result in literally squirting the core out the end of the billet. Often once the billet is cool you can see where the inner layers at the end of the billet moved out from under the top layers.

One trick if you're using a handle welded onto the end, and a power hammer, is to always draw from the handle end out, and if using drawing dies, avoid the last 1" or so of the billet when drawing, and then coming back to it and smashing the end down on flat dies or with the flat of the dies in the final heat, or after every few drawing sessions for large billets.

Same with drawing dies on a press. Work from the handle end, out. The material on the handle end will resist the billet's desire to flow in that direction.
 
With chopping and rewelding the stock for random pattern, I wound't think you would lose more than about 25% especially with that big hammer as you are making a lot of scale lon the floor like some of us do with a smaller press or hammer.
 
Yeah for a random you should lose very little, if you don't restack very tall. Should be down close to 10% total loss under optimal conditions assuming a 200ish layer count.
 
That 'butterfly' effect is normal when using a large power hammer. Don't cut any more off the ends.

One thing I do with finished billets is make the 'ends' the tang end of the blades. This way if any crap is showing, it's in the handle, not the point of the blade.
 
Don Hanson III said:
That 'butterfly' effect is normal when using a large power hammer. Don't cut any more off the ends.
Click to expand...
OK, thanks Don!

As I was thinking about this today, I noticed the scaling that happened under the powerhammer while drawing out was such that the outside edges of the billet, and as such the outer edge of the outer layer would scale off, which would mean that there are more layers in the center of the billet than on the outer edges, which, when cut and stacked would result in what I called the butterfly effect. Don't think I can post pictures here, but I could post the link to the picture from another site (if that's allowed)

So I can see that this was unavoidable with the tools and method I used. My question then, is: what do I need to change to get straighter laminations? I'm thinking one big squish will be better than multiple squishes, thus my search for a press. Or is it a combination of slow squishes for the deep layers and then lighter blows for the more superficial layers?
 
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Unless you have a BIG press, it is tough to get a billet thin. That last 3/8 to 1/2 inch is when you really start turning steel into scale. ;) Something that Don told me a few years back is that you need to hit a random pattern billet with some kind of hammer to make it "more random" looking, I get that effect because my drawing dies on my press are not exactly even from side to side so I have to run the bar bak trough in short bites to straighten out the sideways ban shape, That almost gives me a slight laddering effect on random. The other end of the spectrum would be doing it on a rolling mill that only stretched the bar lengthwise. You run the risk of getting straight layers that way.....too straight. That "butterfly flaw" might actually end up looking interesting when you cut into it.
weo said:
As I was thinking about this today, I noticed the scaling that happened under the powerhammer while drawing out was such that the outside edges of the billet, and as such the outer edge of the outer layer would scale off, which would mean that there are more layers in the center of the billet than on the outer edges, which, when cut and stacked would result in what I called the butterfly effect. Don't think I can post pictures here, but I could post the link to the picture from another site (if that's allowed)

So I can see that this was unavoidable with the tools and method I used. My question then, is: what do I need to change to get straighter laminations? I'm thinking one big squish will be better than multiple squishes, thus my search for a press. Or is it a combination of slow squishes for the deep layers and then lighter blows for the more superficial layers?
Click to expand...
 
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weo said:
OK, thanks Don!

As I was thinking about this today, I noticed the scaling that happened under the powerhammer while drawing out was such that the outside edges of the billet, and as such the outer edge of the outer layer would scale off, which would mean that there are more layers in the center of the billet than on the outer edges, which, when cut and stacked would result in what I called the butterfly effect. Don't think I can post pictures here, but I could post the link to the picture from another site (if that's allowed)

So I can see that this was unavoidable with the tools and method I used. My question then, is: what do I need to change to get straighter laminations? I'm thinking one big squish will be better than multiple squishes, thus my search for a press. Or is it a combination of slow squishes for the deep layers and then lighter blows for the more superficial layers?
Click to expand...
A large hammer is pushing the sides of the billet out, as well as lengthening it. Cutting stacking vs folding adds to this... This results in the pattern on the sides becoming part of the top/bottom. This is what makes the opposing curved butterfly effect on the end of the bar. It's not a problem at all and as Joe said, we want as much distortion and movement as we can get for a random pattern. Straight lines in damascus are something I avoid.
 
Straight lines like what you might expect from using a rolling mill exclusively are good for things like suminagashi or "precision damascus" , but not for random. The pattern on this blade came from a combination of the "irregularities" in my drawing dies and forging the bevels by hand. Up at the spine, you can barely see the mild "laddering" effect that I was talking about in the picture.
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I was shooting for straight laminations because I was planning on doing one billet with a straight ladder pattern and one billet with a twisted ladder pattern to compare.

...I'm still going to do it, just not what I expected...
 
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Ladder looks like ladder with "crooked" layers. Arguably, the more variation you have in the original patten before you ladder, the more of the "3D" effect you can get. i also would not recommend trying to ladder anything lower than say a 180 layer count . 320-400 has worked best for me. Both of these knives are in that range.
weo said:
I was shooting for straight laminations because I was planning on doing one billet with a straight ladder pattern and one billet with a twisted ladder pattern to compare.

...I'm still going to do it, just not what I expected...
Click to expand...
 
Welcome. One thing that I did with the gyuto in the picture was to forge the random patter blllet to the general shape that I wanted but a little shorter and a fair bit ticker than the final blank that I wanted. Layering a billet actually stretches it a little bit lengths even when you are pressing in the grooves. Because the blade was very thin, I heat treated it first and then ground the bevels so as to reduce the chance of it warping. On the big harpoon bowie, i think that I had to fringe the edge down a little bit after laddering and that is why the pattern is a little bolder at the edge. I know a lot of purist say you should forge to shape, but in the case of a number of damascus patterns, you are actually bette roof grind minot the bar to expose different layers. The good news about ladder is that it is less likely to "wash out" when you grind into it regardless of what method you use. As long as the layers are squiggly when viewed from the spine, you are okay.
When you grind into a bar of twist, you can get a VERY different look when you get deep into it. i have seen some guys like Bill Buxton spot a bar of twisted steel, flip it inside out and reeled it, then forge to shape. The inside of a twist bar is where ou find the the star shaped pattern. is is also where you get the REALLY active pattern from twisted W patterns like firestorm and explosion.
 
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