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Grinder-Proof Bike Lock

Use the hierarchy of materials to beat thieving toerags.
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The typical bike lock is not the most sophisticated device. Typically, they're a U-shape or chain made of ~10mm steel, hardened if you spent wisely. Most commonly these are defeated by cutting right through them with a cordless angle grinder and a cut-off wheel. Such things are fantastically efficient because they're made of materials harder than steel.

Materials harder than steel are one of the things that make steel so popular, with silicon/tungsten carbide you can slice right through steel and make it any shape you like, all it takes is horsepower.

If you want to slice through things ending in "carbide" things get tricky. Diamond and cubic boron nitride will do it, but not at all quickly or easily compared to steel. So can we make a bike lock out of tungsten carbide? Well, yes. But then you could smash it with a hammer.

So. Take your favorite bike lock shape. Make it tubular, rather than solid. Fill the tube with an epoxy resin mixed with big/small chunks of carbide and some steel powder and you're done.

The tube shouldn't be anymore vulnerable to forcing with hydraulics. Cutting with a normal wheel will get through the steel and then bog down* in the carbide epoxy mix. Even a diamond saw will have trouble, since the hard carbide is somewhat flexibly mounted in the epoxy, leading to a juddering cut, plus, the steel casing is still in place, and hot diamond dissolves in hot steel.

As a side bonus, the lock should be a good bit lighter.

* dangerously, with any luck. Hopefully, the disk cuts quickly through a section of epoxy and suddenly catches on a chunk of carbide. This would shock-load the fragile disk and shattering may occur. A shattered cut off disk is often dangerous, but proper PPE will protect the prudent thief.

bs0u0155, Mar 09 2020

Chobham armour https://en.wikipedi...wiki/Chobham_armour
" ... composed of ceramic tiles encased within a metal framework ...". We could tell you more, but then we'd have to kill you. [8th of 7, Mar 09 2020]

https://www.indiego...r-proof-bike-lock#/ [xenzag, Mar 12 2020]

Rapid Bike Theft Device https://explosives....oduct/rebar-cutter/
[bs0u0155, Mar 16 2020]

Encapsulated Ceramic Composite Armour https://patents.goo.../US20090114083A1/en
[bs0u0155, Apr 27 2020]

Plastic Armour https://en.wikipedi...wiki/Plastic_armour
Not a polymer, but has plastic qualities. [8th of 7, Apr 27 2020]

Starlite https://en.wikipedia.org/wiki/Starlite
Controversial, and intriguing. [8th of 7, Apr 27 2020]

Proteus https://www.nature..../s41598-020-65976-0
"Non-cuttable" metal / ceramic composite [kdf, Jul 21 2020]

[link]






       You're describing ceramic vehicle armour - Chobham armour <link> - which is Baked and WKTE.
8th of 7, Mar 09 2020
  

       Best advice I ever got was to park your bike next to a more expensive one.
pocmloc, Mar 09 2020
  

       Looking at the Altor SAF link, it occurs to me that for this approach to succeed you're also going to need grinder-proof bike-racks.
Loris, Mar 09 2020
  

       // does not use reactive armor //   

       Sp. "armour"   

       We call that "underspecified".
8th of 7, Mar 09 2020
  

       //Best advice I ever got was to park your bike next to a more expensive one// - indeed! I also lock my bike* with a lock which cost more than the bike

* my commuting bike, not my nice bike or my second-best bike
hippo, Mar 09 2020
  

       When you get your commuting bike on Freecycle like I did, that's not hard. I did have to buy new tyres for it though.
pocmloc, Mar 09 2020
  

       Also, I’m not sure this idea would prevent the car-jack method of breaking u-locks
hippo, Mar 09 2020
  

       A red-on-yellow cardboard tag with the biohazard symbol and the text "CORONAVIRUS - AWAITING DECONTAMINATION" in several languages should be at least as good as a lock - at the moment ...
8th of 7, Mar 09 2020
  

       //Altor SAF// LOOK AT THE SIZE OF THE THING! it's just a normal lock in a thick aluminum case.
bs0u0155, Mar 10 2020
  

       I wuz thinking about a very cheap, tubular lock filled with some substance guaranteed to explode when in contact with air. One might, perhaps, applaud* when the thief cuts through it.   

       [+] for your idea.   

       * while wearing protective clothing, from a safe distance.
whatrock, Mar 10 2020
  

       To act or not to act, that is the question. Whether tis nobler in the mind to suffer the grinders and maliciousness of such vermin, or to bake a simple idea and blow them all away? For surely, ruffians know they misbehave and should reap what they soweth.   

       Halmet, Act 3
whatrock, Mar 10 2020
  

       Love this!
21 Quest, Mar 12 2020
  

       See last link. This thing is totally bonkers.
xenzag, Mar 12 2020
  

       Ha - funny. Didn't notice it. Will delete or fight you for it!
xenzag, Mar 12 2020
  

       Thermite... white phosphorus... large amounts of unstable stuff that goes 'bang!' and scatters courage and various body parts...   

       Yes, the Help file. I know, guv. Off I go. (plods off to revisit the Help file, yet again)
whatrock, Mar 12 2020
  

       Perhaps the traditional U-shaped design could be upgraded with a series of free spinning beads slipped over the U. Hard to angle grind someothat keeps rotating. The thief could angle their grinder (heh) 90 degrees but that makes their task much more difficult and slower.
AusCan531, Mar 12 2020
  

       I see no-one's touched the grindr-proof bike lock. Probably just as well.
pertinax, Mar 16 2020
  

       //a series of free spinning beads slipped over the U//   

       Could work, and carbide beads are simple enough to make, although getting them tight enough that you can't get the disk between them could be tricky.
bs0u0155, Mar 16 2020
  

       Make them asymmetric, with a spigot/undercut, then each bead under/overlaps its neighbour.   

       The ends of the sequence are problematic but could be protected with a thick outer sleeve over the beads.   

       Not sure how well that would protect against having det cord wound round the "U" and then initiated.
8th of 7, Mar 16 2020
  

       //Not sure how well that would protect against having det cord//   

       Was about to write an idea for an explosive faster-than-key bike lock unlocker. But, a quick google suggests someone already made one <link>. The good thing about using explosives to steal bikes in public areas, is that the actual bike stealing will likely be a minor component of the legal ramifications.
bs0u0155, Mar 16 2020
  

       That kind of depends on the neighborhood...
8th of 7, Mar 16 2020
  

       //depends on the neighborhood...//   

       True, in the rougher neighborhoods of Philly it would blend in with the general gunfire. Conversely, over the river in Camden, extensive firearms experience is so common that you'd actually draw a small crowd. That's the sort of place it is. I mean, many people think the Iowa class battleship parked on the Delaware is retired. Oh no, that's just the sort of thing you need if you get into a serious disagreement with the population of Camden.
bs0u0155, Mar 16 2020
  

       The importance of this idea goes far beyond just bike locks and into anything with a lock or other grindable/sawable protection on it.   

       Someone with a small safe may want to enhance the combination lock with cut-off wheel resistant tubes surrounding the safe held together by U-shaped locks.   

       Do this at home: "Fill a steel tube with an epoxy resin mixed with big/small chunks of carbide and some steel powder and you're done."   

       The importance of this idea goes far beyond just bike locks and into anything with a lock or other grindable/sawable protection on it.   

       Someone with a small safe may want to enhance the combination lock with cut-off wheel resistant tubes surrounding the safe held together by U-shaped locks.   

       The importance of this idea goes far beyond just bike locks and into anything with a lock on it.   

       Someone with a small safe may want to enhance the combination lock with cut-of wheel resistant tubes surrounding the safe held together by U-shaped locks.   

       Try this with a straight steel tube at a home, if a cut off wheel well not cut through it this is worth a patent search and patent in my opinion.   

       Do this at home: "Fill a steel tube with an epoxy resin mixed with big/small chunks of carbide and some steel powder and you're done."   

       Search the Internet for "how to license a patent" and look up the "Houston Inventors Association COMPANIES LOOKING FOR NEW PRODUCTS."   

       Be careful as:   

       "97% of patents never make any money." Search for that phrase on the net.   

       Search for "most businesses fail within * years" in Google   

       Be careful out there.
Sunstone, Apr 27 2020
  

       //You're describing ceramic vehicle armour//   

       Yes he is. Except that it's not armor. Or ceramic. Or mounted on a vehicle that way. Or anything resembling ceramic vehicle armor at all, actually.
Voice, Apr 27 2020
  

       // an epoxy resin mixed with big/small chunks of carbide and some steel powder and you're done. //   

       That's how ceramic armour is constituted; and the device is mounted on a vehicle, though not as an outer casing.   

       It's creating a core resistant to impact and abrasion, with the same mechanical properties as composite armour.
8th of 7, Apr 27 2020
  

       To be fair, I'm not putting solid ceramic plates in, and the patent for that would contain a statment of use. eg <link>: "protection against blast and ballistic threats. The disrupting layer includes ceramic particles or tiles that disrupt the incoming projectile,"   

       No mention of resistance to abrasive cutting techniques. Having said that I remember a safe design on Tomorrow's world that was chunks of granite in plastic. They had a go at it with chunks of something like granite in it. They showed it holding up against a pavement cutter (not sure what blade they had on, would make a big difference). So abrasive cutting resistant armor isn't novel, but tubular armor elements might be.   

       Still, the way US patents are, I would never attempt to file one for anything. Even though many universities encourage such efforts and have staff to facilitate applications etc. The practical experience of people I know is brutally discouraging. My understanding is that it is the patent holder's responsibility to defend their patents, that is, if Megacorp infringes your patent, you are obliged to a: notice and b: provide legal challenge.   

       Since Megacorp isn't going to advertise their activities, and since legal activities are time consuming and eye- wateringly expensive, individuals of normal means can't hope to challenge infringement. Several academics I know have had patents blatantly infringed (in one case a letter informing them of the intent to infringe), all sought help from their Enormo-Mega Universities. In all cases the Universities did nothing. As it stands, your only hope is to go via the secret-sauce route.
bs0u0155, Apr 27 2020
  

       // chunks of granite in plastic. //   

       That was an updated version of D.M.W.D.'s "Plastic Armour" <link>, which used Penlee granite chippings because of its enormously high crush strength.   

       The original used bitumen, later compositions used a more sophisticated formulation to deliver both thermal, abrasion and impact resistance. The WW2 form was quite flammable - unacceptably so for some applications, but since it was mostly used on the exterior of ships (where water for firefighting is usually in plentiful supply), and was in other ways superior to its competitors, it was widely adopted.   

       It stands up very well in comparative tests against more modern alternatives.
8th of 7, Apr 27 2020
  

       Interesting. A modern version with mineral of choice, carbon fiber and silicone could be applied to practically anything. Could even make an new line of bouncy ovenware.
bs0u0155, Apr 27 2020
  

       Maybe you want something with properties similar to Starlite <link>, but with a silicate or carbide ceramic embedded in the matrix ?
8th of 7, Apr 27 2020
  

       Whatever Starlite is, it's properties aren't great for most applications. Speculation seems to revolve around it being a carbohydrate, which makes sense. People have melted steel in carbonized bread. If you added a dense carbide, it would all fall out of the matrix as it expanded. Worse, if you confined it, the expanding behavior would stress the container tremendously. Especially if there are any volatiles in there, which I'll bet there is, namely water.
bs0u0155, Apr 27 2020
  

       We said "similar to Starlite". Something with elastic and intumescent properties, to resist heat and absorb impact, but capable of mechanically bonding the rigid particles to deal with abrasion.
8th of 7, Apr 27 2020
  

       So there's this fence / wall thingy on our southern border that wants to examine some of this technology...
RayfordSteele, Apr 28 2020
  

       See "Proteus" link. Non-cuttable (is that really a word?) material created through "local resonance and strain rate effects." And the description also claims a "hierarchical structure" as does bs0u0155's original HB writeup.
kdf, Jul 21 2020
  

       kdf, thanks for that. I read it. Wish I hadn't, feels like it was written by 16 year olds. Any how, like a lot of science, they published what worked, namely resistance to angle grinder abrasive cut-off wheels and a water jet. Now, the graph showing stress/strain shows transition to plastic deformation at <20MPa. That's 40 FOLD less than steel, so, I reckon you could cut it with tin snips, maybe even kitchen scissors or a utility knife.
bs0u0155, Jul 22 2020
  

       True - but whatever it lacked style-wise, they did use all of your buzzwords!
kdf, Jul 22 2020
  

       You could go the other way. Make the bike lock with a surface formed of spinning angle-grinder blades, powered by a small internally mounted petrol engine within the lock. Now anyone trying to touch the bike lock will get their touching device grinded off.   

       Make sure the lock doesn't touch the bike though.
pocmloc, Jul 22 2020
  
      
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