I really wish my first customer has chosen a knife with simpler geometry. For future projects of this kind, I will have to make some more attachments for my belt grinder, because it is woefully inadequate for the concave false edge. I messed that up several times already and quite a few times I got frightened that I will have to start all over again. Whether I manage to correct the slight flaws that are in there remains to be seen, my guess would be no. It will cut alright, but it won’t be perfect no matter what I do. Grrr.
This weekend I have spent with grinding as much time as I could – approx 4 hours each day. More is not possible, at least not for me. Grinding on belt grinder is for me very mentally tiring, because I have to concentrate a lot more than I had to when grinding manually. Because whilst grinding on the belt grinder is quicker, it is also possible to make mistakes quicker.
At this point, I should be finished with polishing, but I am unfortunately not even halfway through. Mainly I have myself to blame for this. If you remember, when writing about the kitchen knives I mentioned that after the first grind with the magnetic jig I went back to freehand in order to be able to alternate the angle of attack to get a flatter and more even grind. Well, I forgot to do that with these two knives and I ground them both up to 120 grit ceramic belt on the jig. The result was ever so slightly wavy grind that I had to correct now that the blades are hardened. So I had to start all over at 40 grit and work my way up, sweating profusely whenever my hand slipped slightly. But at least one thing is clear now – whatever misgivings I had about the blades being perhaps not hardened properly, I do not have them anymore. They are extremely hard and tough to grind, which is why it took me so long to get to 150 grit today, which is the point at which I had to call it quits.
Still a long way to go. © Charly, all rights reserved. Click for full size.
I estimate I will need about ten more hours overall, on and off the belt grinder, before I can call these two blades finished. That means at least one more weekend. At least. It also means more than double the time that I think it should have taken me. When I am done with this and with the kitchen knives, I will probably make a batch of these blades as an exercise, I must get the muscle memory and experience and know-how to do a proper job in a reasonable time, I cannot dick around with one blade for months on end anymore.
Could the false edge (which I’d like to call yalman*, as I know no other succinct expression for it) be ground with a cylindrical grinding surface (such as the belt going over a large-radius wheel)?
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* = Thanks to Matt Easton and Ottoman Turks.
@Ice Swimmer, I think large-ish wheel with hard rubber surface would be best. But I do not have such wheels and an attachment for them yet, I have to build that first, which will of course take some time. I also need a set of different platens behind the belt for very shallow fullers and similar thing. It is all work in progress.
I have not much to add, but the Blade already looks beautiful!
I hope youkan work the problems you have out. It is very fascinating to see your approach and I whish you best of luck
The general rule is that as long as you have scratches, drop back a grit and work them out going a different direction until they are gone, then you can step back up the grit. Otherwise you’re doomed to chase scratches forever; I’ve seen knifemakers spend hours chasing a scratch with 800 grit that they could have gotten rid of in minutes with 600 grit.
I utterly loathe chasing scratches but I seem to spend most of my time doing it. It’s just the nature of the beast, I am afraid. Most of my gear can be described as “polishing stuff” because that’s 95% of the task of knifemaking (the other 5% is really fun)
That’s a good-looking blade!
The nastiest tradeoff is between making the edge too thin before the quench, so as to save time polishing it, and risking bends. When I get into composite billets (yesterday I was working on a wrought iron/1095 billet with a cable core!) then I really hate it -- the stuff has internal structure that makes it want to bend, so you have to leave the edge quite thick. In those situations I differentially quench so that the main body of the knife is soft and easier to grind -- but then it’s so tempting to mirror polish the hamon…
By the way, I’ve done the whole set of experiments with various oil and sandpaper (e.g: WD40, break-free, blaster) and it turns out that plain old windex is the best surface dressing for wet/dry paper.
@Marcus, I am adding a spoon of dish detergent into my bucket of water. It does help a bit, but it also plays hell with fingers.
Chasing scratches is a penance. I had a long enough break to forget how much of a penance it is.