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Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 19, 2012 06:04PM
I thought some of the engineering brains 'round these parts might have some insights to offer.
Here in Chicago angle grinders have put a serious dent in the effectiveness of bicycle U-locks.
(Exapmlesmiling smiley


Anyone have any ideas for a design that would render an angle grinder useless, or otherwise cause the thief to give up before completing the act? Thx.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: space-time
Date: January 19, 2012 06:08PM
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: John B.
Date: January 19, 2012 06:23PM
Man, that's really too bad. When I got a Ryobi cordless angle grinder, I called it my "cordless master key" for a while and tried to take solace in the fact that it made lots of attention-getting sparks and noise. If your lock is somewhere out of the way, though, that isn't much of a deterrent.

Do the two sections of that Kryptonite lock separate? (I have some U-locks that separate that way.) If so, maybe you could slide sections of steel/iron pipe up both legs of the U and over the locking barrel as a kind of "armor"?
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Buzz
Date: January 19, 2012 06:35PM
use a bike that nobody would want to steal?
probably give you a better workout, anyway.
only use the good bike when it won't be out of your grasp.
got nuthin.
back when I could last ride (about 18 years ago) when taking the lockable bike, I used three, and sometimes four, different locks, w/ assorted chains and cables intertwined, w/ the idea being that any theft would be more obvious. I used a rack mounted pack to carry the extra weight. the good bike truly never left my grasp or that of a riding partner (bright red 58cm Ciocc, SLX tubing, full Dura Ace).

///
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Tofer
Date: January 19, 2012 06:50PM
Quote
Buzz
use a bike that nobody would want to steal?

This is my tactic. My $20 garage sale bike gets me the 0.5 miles to work and back every day without any worry that it will be stolen. I don't plan on taking it with me (it's in terrible shape after three years of no maintenance and all the elements), so in a few months I'll be trying to figure out the best way to get it stolen. I'll probably end up just leaving it by the dumpster in case someone wants it...
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: kap
Date: January 19, 2012 07:05PM
The recent news is that bicycle thievery has been on a sharp rise. I don't own a fixie so I am safer for now even with an $80 NY U lock ;)



West San Gabriel Valley, California ... for the time being :-)



Edited 1 time(s). Last edit at 01/19/2012 07:06PM by kap.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: michaelb
Date: January 19, 2012 07:30PM
not avail yet, but this could work

[www.kickstarter.com]
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Racer X
Date: January 19, 2012 07:45PM
even with a titanium lock, you could use a diamond studded saw on a grinder, or a diamond studded blade on a cordless SawzAll
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Carnos Jax
Date: January 19, 2012 07:47PM
Yes, but I would wager that the odds of even an angle grinder toting thief having one of those are probably not so great.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: billb
Date: January 19, 2012 07:59PM

+

+


I suppose you could build a little steel cover to cover the locks that would have to be cut off first, but now you have a lot of weight and bulk to heft around and it will only slow a grinder down.


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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Racer X
Date: January 19, 2012 08:06PM
Sure. The goal is to make YOUR bike more trouble to steal than the bike next to it.

As soon as battery powered grinders and SawzAlls became commonplace, locks became kinda secondary. Its now just as easy to cut a chunk of the bike rack out/off, or unbolt it from the studs in the concrete.

You get a guy with a pickup truck and a helper, the helper gets the bike free and in the bed of the truck, and they are a block away in under a minute.

We had a display of Grant steering wheels at my auto parts store, and a display of Clubs next to them. We put a Club on one of the steering wheels, and some idiot lost the key. We had that Club cut in 3 minutes with a carbide burr on a die grinder. If we had a cutting blade, probably would have been a minute.

They just slow people down. I use Clubs on my parked cars, as opposed to my daily driver. I want them to take my neighbors' cars, so I make the Buicks a bit tougher to steal. I have no illusions they are theft-proof.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: michaelb
Date: January 19, 2012 08:06PM
Quote
Racer X
even with a titanium lock, you could use a diamond studded saw on a grinder, or a diamond studded blade on a cordless SawzAll

i havent watched the videos, but i think part of the concept is that the bands flex and would vibrate, making cutting harder.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Racer X
Date: January 19, 2012 08:19PM
that's why you use a diamond grinding tool. Teeth will catch.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: NewtonMP2100
Date: January 19, 2012 08:48PM
......so you are against a little bumping and GRINDING........???



____________________________________________________

I reject your reality and substitute my own!



Edited 1 time(s). Last edit at 01/19/2012 08:52PM by NewtonMP2100.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: cbelt3
Date: January 19, 2012 09:22PM
smear the outside of the lock with a thick grease. That's about all you can do.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: billb
Date: January 19, 2012 09:45PM
Quote
cbelt3
smear the outside of the lock with a thick grease. That's about all you can do.

I suppose you could really be a stinker
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: cbelt3
Date: January 19, 2012 10:28PM
billb... as a teen I'd ride my bike to high school every day (yeah, uphill, both ways.. ). Some schnook decided it was funny to let the air out of my tires every day. After the second day I pumped the tires back up, and packed the Schrader valves with heavy grease.

The next day, after school, I found one tire slightly down in pressure, and a classmate I particularly despised cursing and wiping the grease out of his eyes. Payback isn't a female dog, it's sweet. Very sweet.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 19, 2012 10:41PM
Sorry folks, I had to run out right after posting.
I've got a bit of expertise in the bike theft arena, and most of your suggestions are on the money in terms of lessening you chances of becoming a victim, but I was looking for specifically thoughts on the stated engineering problem/question in the OP, i.e. how a U-lock could be designed that would mess with an angle grinder to the point of deterrence.
(and not leave the user covered in grease :-)




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 19, 2012 10:46PM
Quote
John B.
Man, that's really too bad. When I got a Ryobi cordless angle grinder, I called it my "cordless master key" for a while and tried to take solace in the fact that it made lots of attention-getting sparks and noise. If your lock is somewhere out of the way, though, that isn't much of a deterrent.
I had occasion to cut a lock last weekend with my Ryobi cordless grinder and found that it didn't have the oomph to do the job in an amount of time that wasn't a bit embarrassing. I think the previous times I've cut a U-lock I used one of the contractor-grade grinders (may have been a Bosch.) My batteries are NiCad and have not seen much use since bought in 6/10.
Re: Sparks flying, attracting attention:
29 seconds:
[www.youtube.com]
This particular crew steals almost exclusively bikes locked on main streets-- they don't bother looking for bikes in secluded areas.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 19, 2012 10:49PM
Quote
kap
The recent news is that bicycle thievery has been on a sharp rise. I don't own a fixie so I am safer for now even with an $80 NY U lock ;)
Your $80 NY lock takes an experienced thief about 90 seconds to cut through.
Billb nailed it-- very unlikely a thief will bother with 2 U-locks.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 19, 2012 10:53PM
Quote
Buzz
use a bike that nobody would want to steal?
probably give you a better workout, anyway.
only use the good bike when it won't be out of your grasp.
got nuthin.
back when I could last ride (about 18 years ago) when taking the lockable bike, I used three, and sometimes four, different locks, w/ assorted chains and cables intertwined, w/ the idea being that any theft would be more obvious. I used a rack mounted pack to carry the extra weight. the good bike truly never left my grasp or that of a riding partner (bright red 58cm Ciocc, SLX tubing, full Dura Ace).
///

Per a cop I know who has a special interest in bike theft, a 12" bolt cutters is the tool most often found on a bike thief. A bunch of intertwined cables just takes a few snips.
Most cables tend to be cut under the cover of lots of people and activity. It's incredibly easy to make it look like you're just unlocking your bike while snipping cables.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: billb
Date: January 19, 2012 11:08PM
Quote
Black
Quote
kap
The recent news is that bicycle thievery has been on a sharp rise. I don't own a fixie so I am safer for now even with an $80 NY U lock ;)
Your $80 NY lock takes an experienced thief about 90 seconds to cut through.
Billb nailed it-- very unlikely a thief will bother with 2 U-locks.


stacked is still just a time deterrent
same with bigger

it's about all you can do

a cut off wheel on a portable grinder is a formidable tool
a hydraulic rescue spreader would be even faster
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 19, 2012 11:39PM
OK, so it seems everyone on this forum is an engineer when it comes to nuclear disasters and cruise boats, but nobody understands cutting metal besides billb.
I can live with that.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: davester
Date: January 20, 2012 12:14AM
It seems to me that a grinder-resistant lock would be one that had a flexible and squishy outer covering that would prevent the grinder from getting a good hold on the actual lock and/or would keep snagging on the wheel and sending the grinder flying. It would be incredibly annoying to the grinder operator if the target kept shifting or was not solid enough to push against. I've spent a lot of time operating an angle grinder (not on bike locks) and the trickiest part is when the grinder grabs on something that you don't want to grind.




"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan



Edited 1 time(s). Last edit at 01/20/2012 12:16AM by davester.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: ADent
Date: January 20, 2012 12:15AM
What can stop the die grinder?

Picking a stronger grade of steel would help, but I don't know the difference between the steel they use to make a U-Lock and something more expensive. How due tool steel, A286, and Inconel stand up to grinders vs the standard lock steel?
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: N-OS X-tasy!
Date: January 20, 2012 12:18AM
Clearly what Black seeks is a lock made from adamantium.



It is what it is.
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Re: Metal lock that can't be cut through by angle grinder?
Date: January 20, 2012 01:19AM
Grinder blades can get clogged by some really soft metals, like annealed copper and aluminum. I have not seen a study of the most likely alloy to clog, but I bet there is one. You could make the lock a large enough diameter that the average angle grinder blade can not cut half the way through, but it would weigh 20 lbs.

I know there are some really tough stainless steel and titanium alloys to machine but I do not know if it would be enough to slow down an grinder that much.



in tha 510.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 20, 2012 02:47AM
Thicker and harder metal is not the answer (unless you can keep the weight down, in which case we're into "transparent aluminum" and "tritanium" territory.) More expensive locks are already thicker and harder, and the result is incremental increase in cutting time grossly proportional to increased thickness or hardness.
Some sort of soft outer coating that may coat a blade sounds promising . . . flammable or explosive would be nice but not commercially viable.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: michaelb
Date: January 20, 2012 06:39AM
in the video they cut the titanium bar with an angle grinder but it takes longer tham the ulock and that is when it was clamped in a vise. the bolt cutters didnt cut it. this is all biased and unofficial testing.
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: RAMd®d
Date: January 20, 2012 08:33AM
It would be difficult (read: costly) to engineer, but a series of rollers around the loop and base would spin as the grinder tried to get a purchase.

One might be able to lock some of them down with ViseGrips or similar to get a kerf/cut started, but that might take long enough to make other bikes more tempting.



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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 20, 2012 08:51AM
Quote
michaelb
in the video they cut the titanium bar with an angle grinder but it takes longer tham the ulock and that is when it was clamped in a vise. the bolt cutters didnt cut it. this is all biased and unofficial testing.
It's been a year or two since I've reviewed that particular lock, but as I recall there were other independent tests that showed that it actually was no problem with a bolt cutters and the video was quasi-bogus.




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Black
Date: January 20, 2012 08:53AM
Quote
RAMd®d
It would be difficult (read: costly) to engineer, but a series of rollers around the loop and base would spin as the grinder tried to get a purchase.

One might be able to lock some of them down with ViseGrips or similar to get a kerf/cut started, but that might take long enough to make other bikes more tempting.

Good thinking . . .one key would be that such a lock could not be marketed as "grinder proof" otherwise the thieves would immediately make a project out of proving they can be defeated . . . the roller-bearing design could be touted as a design feature maybe . . . "NO LONGER DO U-LOCKS HAVE TO LOOK BORING!"




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Re: Metal lock that can't be cut through by angle grinder?
Posted by: Buzz
Date: January 20, 2012 01:15PM
Black- depending on my mood at the time, the cables were just added deterrent, a heavy duty blue cable, and a maximum duty red one. The hardened steel chains were the real deal, and a beefy U lock and a couple of serious padlocks were part of the routine; the extra padded chain lock was used when I thought I was really worried. I tried not to lock it up in a crowded area for the very reasons you allude to. FWIW, we really didn't lock the bikes up in areas as bad as Chicago is for bike thievery. While we went by/through gangland Venice regularly, we didn't make it a habit to stop there. Further south at Marina del Rey, Playa del Rey, Manhattan Beach, Hermosa Beach, Redondo Beach, etc. where we were more inclined to stop, are areas where angle grinders and bolt cutters are not as much of a threat. There, it's mostly the unsecured bikes that end up going for joy rides, so the multitude of cables and chains was designed to make the potential thief move on to an easier target.

If you can't avoid high theft areas, I'd lobby for legislation that rewards good Samaritans for photographing bike thefts. Put a $200-$300 bounty on all bike thieves, and advertise the heck out of it, and public thievery would drop... the only bikes that would get stolen would be from secluded alleys. Locks are simply not the proper deterrent... the problem will continue until a proper deterrent is implemented.

///
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Re: Metal lock that can't be cut through by angle grinder?
Posted by: dihydromonoxide
Date: July 14, 2012 05:35PM
how about a u lock covered in free spining ball barings
[www.moma.org]

with sharp hard squre coners that embeded free moving spining balls and enbeded tungston fibers
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