I want to stress up front, that none of these failures is Marcus’s fault.
So, what went wrong this time, I don’t hear you ask? Well, a lot, I am down one blade out of three.
I thought the pairing knife goes on really well, until 320 grit when I noticed a little perpendicular line on the spine. And It was not a line in the damascus pattern – those become visible during polishing, and that is very cool – it is a crack. I do not know when it happened. It might be there from the start, it might have happened when I was straightening the blade, it might have cracked due to the stresses involved during polishing – it is a very thin piece of steel after all. There are also some imperfect welds with inclusions in the piece, but this is not one of them, this is a crack.
Cracked spine. There is one more crack on the other side of the blade too. © Charly, all rights reserved. Click for full size.
No matter the cause, this blade is now irredeemable garbage, the only thing it could be reworked to is an awl,
I am going to finish the piece only as a show of what it could have been, but I am definitively not using any fancy materials for the handle. I planned on using stabilized maple burl (also a gift from Marcus), but now it will probably be just some random piece of birch or oak.
Works on the boot knife also did not go well. First I messed up the grind, bigly, but that was not the problem, that was still repairable, there was enough material that needed thinning out anyway. What was not repairable was the position of the cutting edge towards the blade’s tip. It turns out that I did not hit the 1095 at the center of the blank quite well. My grind was straigth, but the the 1095 in the center of the san mai damascus was bending ever so slightly to the left in this area. Had I positioned my grind just about 0.25 mm to the left, this would not have happened.
The darker cable damascus is reaching all the way to the cutting edge near the tip, where only the shiny 1095 should be.
© Charly, all rights reserved. Click for full size.
I have tried to re-grind the blade, but for that, I had to make it about 1 cm shorter and I do not think it looks as well as it did before, it is too short and stubby. It should become a usable little knife, but I am not happy with it, and I am not finished yet.
Next time I will work with san mai damascus, I will probably first polish and etch the edge to see exactly where the cutting steel is. Too bad I did not think of that before.
All in all, so far this project has made me nearly cry several times and to want to quit knife-making because I am no good at it. When one spends several days with some work only then for all that effort to be for nothing, it has quite an influence on one’s mood.
I’m sorry you’re running into so many problems with this. I know it’s especially frustrating when you’ve really been looking forward to something like this.
Ah -- so frustrating. Look at it this way: what you got was experience. (Experience is what you get, when you don’t get what you wanted.) This one must really hurt though. Much sympathy.
So frustrating. I’m sorry about that. I wish things went better, but there’s always the learning. Every time with the learning. I tell the universe I’d be happy to pay attention during my successes as well, but the universe seems to be of the opinion that we humans need the failures for the learning.
Hope that helps you take what you can from this and move on to better things.
https://www.youtube.com/watch?v=qs6G9tisVdU
Oh Nooooooooooo!!!!
The crack is almost certainly from trying to straighten the blade. If it’s one of the pieces of 3-layered bar, what would have happened is the central layer and the cladding did not bend at the same rate. *pop*. You really cannot do much to straighten damascus after a quench, unless the blade is differentially hardened -- in which case the back is placing constant stress on the martensitic edge which will pop someday when someone least expects it. It’s best not to do that at all.
I feel like I should have included some kind of write-up on how to use the bars, along with the bars. There are a lot of tricks that apply to damascus that do not apply to monosteels. Mostly, it’s just more problems.
With respect to bending, normalizing helps but it’s more important to keep your bars nice and thick. I usually keep the back around 4mm and the edge around 3mm and sometimes (if I am not trying for a hamon) I’ll just leave the whole bar around 4mm. Grinding on the bar once it has hardened amounts to many many thermal cycles on the steel and it gets nice and springy after a while. If I don’t want to grind on a lot of hardened steel, I thin the edge down around 3mm and differentially harden it, so long as there is enough meat on the back of the blade to keep it from bending.
If you re-quench damascus it usually doesn’t survive, is my experience, unless there’s a lot of metal on the back supporting the edge.
With respect to losing track of the core -- that’s an old problem and, as you say, the solution is to grind back where you want the edge to be, then do a test-etch and see if it’s correctly positioned. If it’s not, you can hammer it slightly but that’s just asking for a bend at quench-time. Usually, I grind the edge back to make sure the core is positioned, then etch it and rinse it and let it sit overnight. If there are little rust lines on the edge then those are most likely cracks and the bar is a throw-away unless you want to grind it back. Twist bars are a special case because there are often “lips” on the outside that form as a result of the twist. Usually those are welded down but sometimes they appear as cracks that go into the bar for a short distance and then end. Usually that’s a sign of a rectangular bar that was twisted, not a round bar.
I feel bad, even though you say it’s not my fault. I probably could have increased your probability of pulling out a good knife if I had just taken the time to do some documentation. So I’ll apologize for my laziness!