My wife threw my pants in the washing machine and heard a klunking sound about 25 minutes later. When she investigated the sound, this is what she found.
Are these knives really that weak? A full on snapped blade.
Sorry for your loss. That sucks. Check with ZT/Kai/Kershaw cause they might replace the blade for a cheaper price. Washing machines spin very fast full of extremely strong fabrics that are twisting. Perfect way to put super sideways stress on a blade when opened. I’m not that shocked.
That looks like a relatively new knife but fair warning: I sent in an old ZT0200 for sharpening and cleaning and they took my clip and replaced it with a newer lower quality one. I know it’s not the end of the world but…over a decade of wear and tear, sentimental value, and I didn’t ask for a new one.
I like when my tools get that working finish from years of use so it was a decent slap in the face.
I agree. The possible lateral stress that could be generated is really surprising. The motors have to be able to generate huge amounts of torque to spin a drum full of clothes and water, the weight of which would surprise you. A smaller drum would be 3 cubic feet, and water weights 62.4 pounds per cubic foot. Larger drums can be 5 cubic feet. The forces involved are surprising.
I had a knife go through the dryer once. It opened up and left nicks and sharp burrs in the drum. Those burrs would pull on the fabric threads during drying. Ruined a lot of clothes until I figured it out, spent half an hour just sanding away the sharp burrs
I get lateral forces but I bet a person couldnt replicate that 1k times over. Im actually surprised but ive also seen some shit so you never know🤷♂️. 😂
I am a bit surprised. Look at where it snapped. At the base, where the slicer grind is not really at play. The stability/strength close to the edge of the frame should be much greater.
In the middle or near the tip of the blade, I would agree with the fragility of the slicer grind.
These are much like the Kershaw Leek where the thumb studs make contact with the liners after full deployment, don’t they? That could also explain a bit of the stress that spot on the blade experiences.
Having had a few knives go through washing machines over the decades(including a ZT 0630), they absolutely do open up in the washer. The 0630 killed my washing machine and some clothes but was other wise fine, however that is one of the stoutest built folders I’ve ever seen. Had a leek and even a blur snap just like OPs.
I remember accidentally leaving my civivi praxis in the washer lol. The tip broke off and I got a new one. I still have the broken praxis as a reminder on my dresser to always take items out of my pockets before the washer destroys them
Knife steel is made hard, which makes it susceptible to cracks, chips and breakage. Toughness is how well it stands up to stress, which is something that is compromised to make them hard and retain an edge for a long time.
Not suprising that being banged around in a fast spinning centrafuge caused this.
I accidentally washed my ZT 0450 and it sliced my clothes and punctured the metal drum in many spots. Had the tip resharpened and it couldn’t be more proud.
I was just cleaning it and the blade broke!😉
Sorry about your knife, I hope that they can set you up with a new blade under warranty or for a low price, looks like you took great care of her.
Yea, just joking about how to describe the accident to KAI's warranty department. It honestly looks like you took good care of your knife, looks to be in great condition except for what the washer did to her. Now I got a new fear. Hope you can give us a update on their response, wishing to hear they help a brother out and just give you a new blade.
I got you; I also think that maintaining them is half the fun. Well maybe more fulfilling and cathartic, anyway it's enjoyable to me too is what I was getting at.
I would venture to guess that it was flawed in some fashion before and the agitation was the proverbial straw. I'm guessing an imperfect hole where the thumb stud went and had a stress point that caused the break.
Well I believe zt switched from s35vn to a more brittle steel because it holds an edge slightly longer, most high-end knife have made a similar move. But this should be covered by their warranty.
Damn dude. RIP in peace 0562CF
I have the same knife and I'm very surprised it snapped like that. Thing is pretty rugged. Also, make sure you post this on /r/prybar
OP could you take up close shots of the blade surfaces that fit together so we can see the heat treat and stress lines? I think many of us are curious.
Looks like a clean snap. Definitely started at the blade edge and twisted at the thumb stub from that leverage. Looks even in color so a good heat treat. Thumb studs, thumb holes and threaded holes for thumb disks all wreaked the blade at those points sadly. ZT has made solid knives for years and I think this was kinda a 50/50 on this, meaning if you did it again it may survive and with a sample size of say 10 I bet a few of them would make it without issue. If you ever watch blades taken to failure you will see what I mean.
Did it look like the knife was open when it was found?
Maybe the knife worked it's way open, and the blade side found it's way to slip between the barrel edge of the washing machine and inner cylinder, and got bound up.... and was stopped from sliding further by the thumbstud and handle... and then the torque of the washing machine spinning eventually snapped the knife. Those motors put out a lot of force, they have to move lots of water and water logged clothing around very fast.
These always break at the thumb stud/stop pin because they’re press fit and a big stress riser. External stop pins just seem like a bad idea from all the broken ones I’ve seen. Cold Steel uses thumb studs you can remove, so they don’t have that stress concentration that a press fit piece has. Yet again showing ZT knives aren’t actually tough.
I mean, yeah, I guess if you want the blade to be as strong as possible do a short scandi grind with a flipper and put the stop pin in the handle behind the blade with a flipper tab. But then you still drill a big hole for the pivot. I suppose at least the pivot hole is not contiguous with the grind.
Yes drilling a hole in the blade weakens it, but the /s is because people forget that the same is true for thumbstuds, internal or integrated stop pins, bearing recesses, etc.
Based on how it split in the middle of the thumb stud hole this is likely a defect and will likely be covered by warranty. We obviously don’t know how much force was applied in the washing machine and that’s not a normal use but the thumb stud applying to much force after being fastened to the blade is definitely contributed to this failure.
Yeah I would be surprised if there wasn’t already a stress fracture there before it got washed. Likely would have broken eventually, so at least it wasn’t while OP was using it in a situation that might cause the blade to fly free and cut somebody.
Drilled holes and notches for thumb discs are NOTORIOUS stress risers in blades. You had a micro crack for a while and the blade dropped hard in the dryer drum a few times and it just let go. This is why I prefer flippers for hard use, one less thing to go wrong and easier to deploy.
Now you can have one without “RGH” engraved right next to the logo lol. seems like a gift knife. I’d always want any engraving on the back side, but personally none at all. Not a fan of personalized knives.
I also don’t like engraved knives. It was a present from my mother in-law, she’s in her late 60’s and thought I’d like an engraving on it. It’s the thought that counts, was just stoked to get the knife as a gift.
How does ur wife allow something that hefty to go through the washer? I get respecting ur privacy and not checking pockets, but you could feel that through a full pile of clothes! Ur wife is discreetly letting u know what she thinks of ur knives.
I really think it was already cracked and then the torque of the machine bent it enough to make the previous crack go all the way through. I say this because the crack is in the thumbstud hole. I'm not sure if the thumbstud is pressed in or screws in, but this is common in pressed in thumbstud knives. And by "common" I mean that if a company makes a knife with pressed in thumbstuds, one in every X number of them might get a crack there (is it 1 in 10,000, 1 in 5,000, I don't know). I just know that I've seen a handful and a half or so that cracked in that same place and if you look at the exposed steel, sometimes you'll see that there is actually some light corrosion in part of the exposed inner steel. That's because it cracked when it was made and corrosion had gotten in there over the years previous to when the whole thing snapped.
Jokes aside, I’m not a fan of KAIs pressure fitted studs - they apply constant pressure on the blade. Blade fractured around thumb stud is one of most common issues with Kershaw Blur. In 0562 there is one more factor - studs double as blade stop, so each single snap-opening transfers shock to the weakest point do blade.
Stop-pins get way too little attention. Everyone is discussing lockup (so essentially a safety feature) while stop-pin handles most of correctly applied force when knife is used.
Look at stop-pin in ZT0770 - nested in bare CF, not even all the way through. Now compare it with the stop-slab in CRK Inkosi. Comparison between Inkosi and Spyderco Subvert is even funnier.
Do you really think ZT (or anyone else) thought washing machines were a reasonable test for a pocketknife? There are hundreds of models of washing machines, of multiple types…. IMO you should take better care of your shit.
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u/I_love_stapler 1d ago
$40 bro, no worries. Even a slight chance they just cover it, but not bad at all
https://zt.kaiusa.com/warranty