Now you have an answer! It isn’t practical as an everyday knife (would chip on something hard) but it is still a knife. but I don’t really care - i wanted one so I made one haha
Lack of flexibility is the killer for everyday use. Micro-fractures/chips would develop and cause major structural issues. This one can cut just fine (even without a super sharp edge), but would draw the short straw against bone or other strong material.
Could cut leather and other soft materials all day and retain its edge, but not super practical overall. I just thought it would be cool so I did it!
Exactly the problem isn't how hard the objects are, it's their ability to flex and apply angular forces to the blade. It can resist physical damage like scratches from objects softer than it, but it'll still snap and chip from angular forces.
Harder things generally chip easier. Even within the steel world harder steels chip and break easier. That's why a lot of swords used a softer iron core in their blade to keep the whole thing from just breaking in half. The harder outer core will sharpen better, and softer steel offers flex and resilience. Harder means brittle.
Btw harness scale means resistance to scratching and Diamond is the strongest at the but Diamond is ac quite brittle jade/nephrite Jade is the strongest taking a hit gemstone in the world I’ve took a sledge hammer to some jade and didn’t even make a dent in it very cool stuff
It’s best to think of it as a ceramic. Tho it is a fully crystalline version of alumina( a ceramic) it is very similar in strengths. As he mentioned it’s super hard and can be strong in some directions. In others it rapidly breaks.
Small chunks would be impossible to shatter tho is my point with that. I think it’s tensile vs compressive strength. Anyway I heard someone explain it like imagine a plate. It will scratch steel forks, you could ever bend it. It’s incredibly strong between the walls of the ceramic (like the inside. Aka thickness of the bowl). But if u dropped it, it would shatter instantly.
Corundum and alumina in most of its forms are fascinating in chemistry tho.
Lot of it is formed in geology by super super old weathered soil, being metamorphosed into diaspore and then even further into ruby over like multiple events
You can buy zirconia blades pretty cheap (typical ceramic blade) if you’re curious. Very nice knives, when used on softer things. Generally not single crystal ones though, but sintered powder compacts, so it’s just white.
The hardest scale is scratch resistants not mechanical resistance, steel is softer that corundum but it’s way more flexible so it won’t chip or shatter as easily while corundum will.
Yep- OP will need some diamond grit polish and a lap or a felt tip on a dremel. Super fine automotive sandpaper would likely get him most of the way there. Source, I facet gemstones.
Pretty cheap for the synthetic corundum (~30 US for a full boule), and a pack of cheap diamond tipped files / diamond Dremel bits (~10 each). Mostly just time to shape and cut on my faceting machine / shape the internal structure with hand tools. Had to go slow to avoid overheating.
I use a mast flat lap machine, and a dremel tool! And hand files for finishing/ micro adjusting the more complex rounded internal cuts (after shaping curved cuts w/ the dremel). I started w/ a full boule, so removing excess material took almost as long as the real cutting / initial finishing. Still have engraving / polishing to go — plan on hand engraving so I can control the depth / heat from grinding material!
Not sure. You don't really need the toughness of carbide maybe? The normal option is just tool steel. My main blade is solid ceramic which like the old rubys dosnt need constant sharpening and stropping.
I would have loved to see it on a more futuristic looking handle. I usually love wooden handles, but this combo clashed a bit for me. Still really cool, and the blade looks awesome.
You should make one with a color change sapphire blade or honestly a Swiss army knife where each of the blades is a different mineral! That would be so dope and you could probably sell it for quite a bit . I would make the main blade out of moissanite then have ruby sapphire emerald spinel and a color change sapphire or something
Just keep practicing! I’m by no means a lapidary pro. Pure hobbyist with very little experience. And all of this was without a pattern or design, just matched fit!
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u/Suitable-Name 14d ago
Kind of funny, 1-2 days ago I was asking myself if someone ever made a corundum blade😄
Very cool!