The fact that the blade is so thick that it reacts like an thin hammer and not a katana. It do not cut but completely smash the objects !

As a bladesmith, this pisses me off. As a bro, this is freaking awesome. Mike, if you see this, i can probably answer most of your questions about knife/sword/weapon making.

"Have you ever seen an invisible sword?" Well no, it's invisible.

I'm thinking about improving V1 of the sword, which is obviously going to cut better because of the thinner profile, and making another video comparing that with a real katana. I was also swinging the final sword like a bat, because it lacked cutting abilities but it had a lot of power. Anyways Let me know if you’d like to see an improed version of V1, in which I fix all the mistakes I made, including a better slicing technique! Edit: I’ll do it Ps: the reason I kept the katana that thick, is because it would otherwise bend just with gravity. So the improved version of it is going to be shorter, kinda like a real sword.

The right angle you cut into the blade where the handle and blade meet is what caused the break, not the added thickness of the handle. The same thing happens with steel weapons - they call it a stress riser. A rounded transition from handle to blade would help avoid it.

Mechanical engineer here. By making a 90 degree angle between the blade and the tang in the handle you created a stress concentration there. Abrupt changes in geometry like this create localized stresses far greater than the average stress, hence why your blade snapped there. Fun video!

A true bladesmith does not make mistakes. Just smaller knives. I’d like to see a test with v1 too. I know it didn’t match the title of the video, but your blade geometry was significantly more conducive to cutting through stuff.

14:41 truly invisible 😂

15:02 swordmaker here. When you make a sharp transition like between the tang and blade you create a stress riser. You need to create a round transition.

Airport security isn’t gonna like this one..

1:14 fact that NOKIA is one of the indestructible items mentioned here....🤣🤣🤣

The biggest reason your handle snapped off is the geometry of your sword. Having those sharp interior corners creates a stress concentrator. It's like if you have a 10 lane highway suddenly shrink into a 1 lane country road with no transition. All the cars (stress lines) have to bunch up at that point, cramming into that tiny area with no easing into it. It works when traffic is low (like swinging the swrod through the air), but the moment there's any serious traffic (like hitting the pineapple) there are too many cars trying to go into that 1 lane. For the cars, they just can't move anywhere, for your sword, it breaks. You will always run into this issue with making the grip smaller than the blade, but adding internal radii or some way to gradually reduce the size, will help to prevent this failure in the future. That will always be your point of failure on a sword made out of a single material. Katanas, even though they are made from one piece of steel, have different hardnesses at different parts of the blade and grip effectively making them multi-material sword. I bet you that if you were to take your V1 sword, even though it is a sharper blade, you will have the handle snap off even if you don't make the handle thicker. It's just a nature of your sword geometry and really only something you can learn from spending too much time reading books, or breaking things like your doing, which is how the books were written in the first place. I also don't want to invalidate your own discovery of adding material to the handle making it stiffer and contributing to the blade breaking. That is definitely a part of it and an awesome insight to have found. I just want to highlight that your 2D geometry has as much a roll in the strength of the blade as the 3D geometry does.

This is his weaponmasters arc. First he mastered the fight and now he is learning the forging.

*"Glass is glass, and glass breaks."* that reference made me smile :) Edit: That phrase is commonly said by a tech channel, JerryRigEverything. High quality content, highly recommend it. (Just finish this video first, it's worth it 😙)

"Have you ever seen an invisible sword?" No sir, I have not.

"When it's wet, it looks great" His expression 😭💀

“Glass is glass and glass breaks” loving the Jerry rig reference

so, coming from combat robots where polycarb is used a lot, i can tell you that cyanoacrylate makes polycarb brittle. it was the ca glue reacting with the polycarbonate that made it turn brittle. there is a chemical bonding agent made to glue polycarbonate, but isn't a glue, it effectively melts the 2 pieces together making it almost as strong as if it were 1 whole piece

14:35 Katana becomes really invisible 😂

Alright so hear me out: There is another Japanese Martial Arts style that would make better use of the material, both in regards to its transparency and ability to bend. I believe it’s called Owari Kan-Ryu, but I just call it the Wobbly Spear technique. In essence, you grab a spear near the bottom and with your lower hand push it back and forth (sliding it through your higher hands grip) so as to cause the tip of the spear to wobble in a circular pattern. It helps to get past guard stances, and would likely benefit greatly from having an invisible spear used.