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#51
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What's The Deal with Titanium Chain Locks?
Impressive Carl
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#53
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What's The Deal with Titanium Chain Locks?
On Sun, 30 Jul 2006 07:44:18 -0700, Mark Hickey
wrote: wrote: But titanium is as easy or easier to cut than steel if you're using a hand hacksaw to destroy a single chain link. This is very much counter to my own experience. I've been absolutely amazed at how long it takes to cut through a titanium quick release skewer bolt - MUCH longer than it would a similar piece of steel. Similarly, drilling through titanium takes much, much longer than steel, IME. I think your (snipped) information on cutting/machining titanium supports my experience. Perhaps a well-schooled thief with a very sharp hacksaw and appropriate lubrication would do better... but I suspect most of 'em would be frustated by the effort required to cut through a U-lock's worth of titanium. I can't compare how long it takes to saw frames in half though, since I've never had the occasion to do so. ;-) Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame Dear Mark, Steel and "titanium" are alloys, which vary, but . . . "Hardness. Titanium is a much harder metal than aluminum and approaches the high hardness possessed by some of the heat-treated alloy steels. Iodide purity titanium has a hardness of 90 VHN (Vickers), unalloyed commercial titanium has a hardness of about 160 VHN and when alloyed and heat-treated, titanium can attain hardnesses in the range of 250 to 500 VHN. A typical commercial alloy of 130,000 psi yield strength might be expected to have a hardness of about 320 VHN or 34 Rockwell C." http://www.key-to-metals.com/Article126.htm Here are an amateur's results for testing bike locks and chains (no titanium): http://www.slate.com/id/2140083 Somehow I doubt that he was using a very good hacksaw blade. Here's a single HSS hacksaw blade for $1.09: http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32 Here's the common 8-cent carbon blade in a $4 pack of 50 blades: http://www.harborfreight.com/cpi/cta...emnumber=37155 Cheers, Carl Fogel |
#54
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What's The Deal with Titanium Chain Locks?
wrote:
But titanium is as easy or easier to cut than steel if you're using a hand hacksaw to destroy a single chain link. Mark Hickey wrote: This is very much counter to my own experience. I've been absolutely amazed at how long it takes to cut through a titanium quick release skewer bolt - MUCH longer than it would a similar piece of steel. Similarly, drilling through titanium takes much, much longer than steel, IME. I think your (snipped) information on cutting/machining titanium supports my experience. Perhaps a well-schooled thief with a very sharp hacksaw and appropriate lubrication would do better... but I suspect most of 'em would be frustated by the effort required to cut through a U-lock's worth of titanium. I can't compare how long it takes to saw frames in half though, since I've never had the occasion to do so. ;-) wrote: Steel and "titanium" are alloys, which vary, but . . . "Hardness. Titanium is a much harder metal than aluminum and approaches the high hardness possessed by some of the heat-treated alloy steels. Iodide purity titanium has a hardness of 90 VHN (Vickers), unalloyed commercial titanium has a hardness of about 160 VHN and when alloyed and heat-treated, titanium can attain hardnesses in the range of 250 to 500 VHN. A typical commercial alloy of 130,000 psi yield strength might be expected to have a hardness of about 320 VHN or 34 Rockwell C." http://www.key-to-metals.com/Article126.htm -snip- While not an expert, my intuition is that a surface treatment or full tempering is the difference between Mark's experience (difficult) and my own ( no problemo) Things I cut easily include handlebars, steerers and a stem (that was curiosity, not actual work). There is probably a wide range of hardness from annealed to tempered material so my earlier comments I haven't cut a Habanero frame either. But milling head tubes is straightforward with TIN tools and 'aluminum' cutting fluid. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971 |
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