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#52
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Bearing damage?
On Fri, 26 Dec 2008 20:31:01 -0600, A Muzi
wrote: [snip] I avoided the recent 'water bottle' thread but we use two castoff bottles on each desk. Tall for pens, markers, scissors, small files, etc, short for valve caps and a Campagnolo crank extractor. [snip] Dear Andrew, Typical water-bottles used to store valve caps: http://www.freelandind.com/figalvtanks.htm Cheers, Carl Fogel |
#53
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Bearing damage?
In article ,
A Muzi writes: The manufacturers of steel pinned cranks seem to feel a heavy cast steel press with 42:1 leverage driven forcefully ( an able man puts out about 80 pounds with both arms just below shoulder height) is a better approach. That is a humongous amount of pressure. Here are two clever designs, a VAR #7 crank press and a set of S+S couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG When these cranks were still common, even new premium quality Sugino cranks on Sugino spindles would fail in a day or two of riding when the assembler neglected to remove, lubricate and press the pins properly. For forcing barrel-chested or wrongly-sized cotter pins into straight-tapered holes, I'm not surprised. But cotter pins are not barrel-chested. I actually have a few in my stock -- I've slid dial calipers down them, and there's no widening in their middles. Straight taper pins; straight taper holes. As it should be, as long as there's a perfect fit with no slop. Although one might get a small amount of pin/spindle contact by drawing up the nut, the forces at that contact will work it free and deform the pin's surface in short order if the pin moves at all. We don't (didn't?) want a "small" amount of pin/spindle[/crank] contact. We want (wanted?) ~full~, tight contact all along the length of the pin. That calls for proper fitting, not cheap-assed swage-fitting where the pin is fat in one localized spot, and loose (or loosening) everywhere else. And the only reason to "lubricate" cotter pins (w/ appropriate grease) is to be able to easily pop them out in order to service the BB. They don't fail from inadequate greasing. Might bend the threaded section when driving them out, but that goes with the territory. And there's an acquirable "touch" for avoiding that. Well, it's mostly luck. cheers, Tom -- Nothing is safe from me. I'm really at: tkeats curlicue vcn dot bc dot ca |
#54
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Bearing damage?
In article ,
(Tom Keats) writes: In article , A Muzi writes: The manufacturers of steel pinned cranks seem to feel a heavy cast steel press with 42:1 leverage driven forcefully ( an able man puts out about 80 pounds with both arms just below shoulder height) is a better approach. That is a humongous amount of pressure. Here are two clever designs, a VAR #7 crank press and a set of S+S couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG When these cranks were still common, even new premium quality Sugino cranks on Sugino spindles would fail in a day or two of riding when the assembler neglected to remove, lubricate and press the pins properly. For forcing barrel-chested or wrongly-sized cotter pins into straight-tapered holes, I'm not surprised. But cotter pins are not barrel-chested. I actually have a few in my stock -- I've slid dial calipers down them, and there's no widening in their middles. Straight taper pins; straight taper holes. As it should be, as long as there's a perfect fit with no slop. Although one might get a small amount of pin/spindle contact by drawing up the nut, the forces at that contact will work it free and deform the pin's surface in short order if the pin moves at all. We don't (didn't?) want a "small" amount of pin/spindle[/crank] contact. We want (wanted?) ~full~, tight contact all along the length of the pin. That calls for proper fitting, not cheap-assed swage-fitting where the pin is fat in one localized spot, and loose (or loosening) everywhere else. And the only reason to "lubricate" cotter pins (w/ appropriate grease) is to be able to easily pop them out in order to service the BB. They don't fail from inadequate greasing. Might bend the threaded section when driving them out, but that goes with the territory. And there's an acquirable "touch" for avoiding that. Well, it's mostly luck. It just occurred to me: most of my bikes have been Japanese imports, or Japanese/Canadian collaberations (especially Apollo and Sekine.) I'm a Vancouverian canadian, and we've had our own localized bicycle trade. So maybe our bicycle design experiences differ from that. If cotter pins were to be barrel-chested, it seems to me they should be made of a softer & more pliable metal than hard steel, that would spread like butter under pressure, the better to fill in the gaps, while still retaining enough interface. But to anyone else reading this: don't let your LBS flog-off unto you the wrong cotter pins. cheers again, Tom -- Nothing is safe from me. I'm really at: tkeats curlicue vcn dot bc dot ca |
#55
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Bearing damage?
Tom Keats wrote:
The manufacturers of steel pinned cranks seem to feel a heavy cast steel press with 42:1 leverage driven forcefully ( an able man puts out about 80 pounds with both arms just below shoulder height) is a better approach. That is a humongous amount of pressure. Here are two clever designs, a VAR #7 crank press and a set of S+S couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG When these cranks were still common, even new premium quality Sugino cranks on Sugino spindles would fail in a day or two of riding when the assembler neglected to remove, lubricate and press the pins properly. For forcing barrel-chested or wrongly-sized cotter pins into straight-tapered holes, I'm not surprised. You are conjuring up unreal circumstances. The Best cotters were from "Acier Dupratnik" and were of high strength steel. Just the same, they were designed to be filed or machined to identical flats and they could be pushed through the bare crank with little effort. The press fit comes when the spindle is in the crank and the cotter inserted to arrest it in a rotationally fixed position that must be identical for both cranks or sprinting would impractical. But cotter pins are not barrel-chested. I actually have a few in my stock -- I've slid dial calipers down them, and there's no widening in their middles. Straight taper pins; straight taper holes. As it should be, as long as there's a perfect fit with no slop. It would be unimaginable that Acier Dupratnik would go to all the trouble of machining these cotters from high grade steel bar stock that wasn't straight. The way you say that, I become ever more certain that you have no experience with high quality racing bicycle cotters, the mainstream when I began bicycling over longer distances. Although one might get a small amount of pin/spindle contact by drawing up the nut, the forces at that contact will work it free and deform the pin's surface in short order if the pin moves at all. We saw many of these from people like you who could not visualize how great the forces are in this interface and that one crank puts the major load on the narrow part of the cotter-flat while the other did so on the widest part. You have your choice. My choice was to have the retaining nut on the trailing face of the crank at the top of the stroke. We don't (didn't?) want a "small" amount of pin/spindle[/crank] contact. We want (wanted?) ~full~, tight contact all along the length of the pin. That calls for proper fitting, not cheap-assed swage-fitting where the pin is fat in one localized spot, and loose (or loosening) everywhere else. Well you can't do that anyway, because that would not leave cranks 180° apart as they should be. And the only reason to "lubricate" cotter pins (w/ appropriate grease) is to be able to easily pop them out in order to service the BB. They don't fail from inadequate greasing. Might bend the threaded section when driving them out, but that goes with the territory. And there's an acquirable "touch" for avoiding that. Well, it's mostly luck. That's the classic demise of cotters. That is why one doesn't extract them without a pair of new ones in the event of a squashed thread. Jobst Brandt |
#56
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Bearing damage?
Tom Keats wrote:
In article , A Muzi writes: The manufacturers of steel pinned cranks seem to feel a heavy cast steel press with 42:1 leverage driven forcefully ( an able man puts out about 80 pounds with both arms just below shoulder height) is a better approach. That is a humongous amount of pressure. Here are two clever designs, a VAR #7 crank press and a set of S+S couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG When these cranks were still common, even new premium quality Sugino cranks on Sugino spindles would fail in a day or two of riding when the assembler neglected to remove, lubricate and press the pins properly. For forcing barrel-chested or wrongly-sized cotter pins into straight-tapered holes, I'm not surprised. But cotter pins are not barrel-chested. I actually have a few in my stock -- I've slid dial calipers down them, and there's no widening in their middles. Straight taper pins; straight taper holes. As it should be, as long as there's a perfect fit with no slop. Although one might get a small amount of pin/spindle contact by drawing up the nut, the forces at that contact will work it free and deform the pin's surface in short order if the pin moves at all. We don't (didn't?) want a "small" amount of pin/spindle[/crank] contact. We want (wanted?) ~full~, tight contact all along the length of the pin. That calls for proper fitting, not cheap-assed swage-fitting where the pin is fat in one localized spot, and loose (or loosening) everywhere else. And the only reason to "lubricate" cotter pins (w/ appropriate grease) is to be able to easily pop them out in order to service the BB. They don't fail from inadequate greasing. Might bend the threaded section when driving them out, but that goes with the territory. And there's an acquirable "touch" for avoiding that. Well, it's mostly luck. If I had a bike with cotter cranks that needed servicing, I would take it to the shop with proper tools, such as Mr. Muzi's. A cotter pin that does NOT require significant force to insert will NOT form a press fit, which is what this interface requires to function as intended. -- Tom Sherman - 42.435731,-83.985007 LOCAL CACTUS EATS CYCLIST - datakoll |
#57
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Bearing damage?
On Sun, 28 Dec 2008 03:29:26 +0000, jobst.brandt wrote:
Tom Keats wrote: The manufacturers of steel pinned cranks seem to feel a heavy cast steel press with 42:1 leverage driven forcefully ( an able man puts out about 80 pounds with both arms just below shoulder height) is a better approach. That is a humongous amount of pressure. Here are two clever designs, a VAR #7 crank press and a set of S+S couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG When these cranks were still common, even new premium quality Sugino cranks on Sugino spindles would fail in a day or two of riding when the assembler neglected to remove, lubricate and press the pins properly. For forcing barrel-chested or wrongly-sized cotter pins into straight-tapered holes, I'm not surprised. You are conjuring up unreal circumstances. The Best cotters were from "Acier Dupratnik" and were of high strength steel. Just the same, they were designed to be filed or machined to identical flats yeah, good luck on the fantasy of /that/ ever being achieved. and they could be pushed through the bare crank with little effort. The press fit comes when the spindle is in the crank and the cotter inserted to arrest it in a rotationally fixed position that must be identical for both cranks or sprinting would impractical. red herring. But cotter pins are not barrel-chested. I actually have a few in my stock -- I've slid dial calipers down them, and there's no widening in their middles. Straight taper pins; straight taper holes. As it should be, as long as there's a perfect fit with no slop. It would be unimaginable that Acier Dupratnik would go to all the trouble of machining these cotters from high grade steel bar stock that wasn't straight. eh? what's that got to do with subsequent inaccuracy meted out at the hands of the lbs??? The way you say that, I become ever more certain that you have no experience with high quality racing bicycle cotters, the mainstream when I began bicycling over longer distances. cotters were fundamentally misconceived. your defense of them is bizarre given your favorite hobby-horse of pedal thread fretting, yet apparently you're oblivious to the same effects in this application. Although one might get a small amount of pin/spindle contact by drawing up the nut, the forces at that contact will work it free and deform the pin's surface in short order if the pin moves at all. We saw many of these from people like you who could not visualize how great the forces are in this interface and that one crank puts the major load on the narrow part of the cotter-flat while the other did so on the widest part. You have your choice. My choice was to have the retaining nut on the trailing face of the crank at the top of the stroke. yeah. trouble is though jobst, the greatest area of contact ran the other way... We don't (didn't?) want a "small" amount of pin/spindle[/crank] contact. We want (wanted?) ~full~, tight contact all along the length of the pin. That calls for proper fitting, not cheap-assed swage-fitting where the pin is fat in one localized spot, and loose (or loosening) everywhere else. Well you can't do that anyway, because that would not leave cranks 180° apart as they should be. eh??? all you need is to have the pins finished the same and oriented correctly - this is not rocket science. And the only reason to "lubricate" cotter pins (w/ appropriate grease) is to be able to easily pop them out in order to service the BB. They don't fail from inadequate greasing. Might bend the threaded section when driving them out, but that goes with the territory. And there's an acquirable "touch" for avoiding that. Well, it's mostly luck. That's the classic demise of cotters. That is why one doesn't extract them without a pair of new ones in the event of a squashed thread. you got that bit right at least. ridiculous design. |
#58
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Bearing damage?
"jim beam" wrote:
On Sun, 28 Dec 2008 03:29:26 +0000, jobst.brandt wrote: [...] The way you say that, I become ever more certain that you have no experience with high quality racing bicycle cotters, the mainstream when I began bicycling over longer distances. cotters were fundamentally misconceived. your defense of them is bizarre given your favorite hobby-horse of pedal thread fretting, yet apparently you're oblivious to the same effects in this application. [...] Where did Jobst defend cotter cranks as being a good design? I missed that. Please provide a citation. Obviously, when Jobst took up serious cycling (late 1940's or early 1950's?), there were no quality alternatives to cottered cranks. From Jobst's postings, it appears he abandoned cottered cranks shortly after quality square taper cranks became available. -- Tom Sherman - 42.435731,-83.985007 LOCAL CACTUS EATS CYCLIST - datakoll |
#59
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Bearing damage?
On Sat, 27 Dec 2008 21:55:04 -0600, Tom Sherman wrote:
"jim beam" wrote: On Sun, 28 Dec 2008 03:29:26 +0000, jobst.brandt wrote: [...] The way you say that, I become ever more certain that you have no experience with high quality racing bicycle cotters, the mainstream when I began bicycling over longer distances. cotters were fundamentally misconceived. your defense of them is bizarre given your favorite hobby-horse of pedal thread fretting, yet apparently you're oblivious to the same effects in this application. [...] Where did Jobst defend cotter cranks as being a good design? I missed that. Please provide a citation. serious social perception issue there tom! discuss that with your medical professional. Obviously, when Jobst took up serious cycling (late 1940's or early 1950's?), there were no quality alternatives to cottered cranks. From Jobst's postings, it appears he abandoned cottered cranks shortly after quality square taper cranks became available. as did we all. stupid design. |
#60
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Bearing damage?
In article ,
writes: Tom Keats wrote: The manufacturers of steel pinned cranks seem to feel a heavy cast ste= el=20 press with 42:1 leverage driven forcefully ( an able man puts out abou= t=20 80 pounds with both arms just below shoulder height) is a better=20 approach. That is a humongous amount of pressure. Here are two clever designs, a VAR #7 crank press and a set of S+S couplers: http://www.yellowjersey.org/photosfromthepast/VAR07.JPG When these cranks were still common, even new premium quality Sugino cranks on Sugino spindles would fail in a day or two of riding when the assembler neglected to remove, lubricate and press the pins properly. For forcing barrel-chested or wrongly-sized cotter pins into straight-tapered holes, I'm not surprised. You are conjuring up unreal circumstances. The Best cotters were from "Acier Dupratnik" and were of high strength steel. Just the same, they were designed to be filed or machined to identical flats and they could be pushed through the bare crank with little effort. That's how it should be. Or should be rendered. The press fit comes when the spindle is in the crank and the cotter inserted to arrest it in a rotationally fixed position that must be identical for both cranks or sprinting would impractical. I have enough hand-to-eye coordination and feel to do that. But cotter pins are not barrel-chested. I actually have a few in my stock -- I've slid dial calipers down them, and there's no widening in their middles. Straight taper pins; straight taper holes. As it should be, as long as there's a perfect fit with no slop. It would be unimaginable that Acier Dupratnik would go to all the trouble of machining these cotters from high grade steel bar stock that wasn't straight. The way you say that, I become ever more certain that you have no experience with high quality racing bicycle cotters, the mainstream when I began bicycling over longer distances. The way /you/ say it, you can't even get cotter pins in without a fancy hydraulic press and a bunch of fussy alignment. Although one might get a small amount of pin/spindle contact by drawing up the nut, the forces at that contact will work it free and deform the pin's surface in short order if the pin moves at all. We saw many of these from people like you who could not visualize how great the forces are in this interface and that one crank puts the major load on the narrow part of the cotter-flat while the other did so on the widest part. You have your choice. My choice was to have the retaining nut on the trailing face of the crank at the top of the stroke. I guess the nut is always on top of the cotter pin, and there's nothing anyone can do about that. We don't (didn't?) want a "small" amount of pin/spindle[/crank] contact. We want (wanted?) ~full~, tight contact all along the length of the pin. That calls for proper fitting, not cheap-assed swage-fitting where the pin is fat in one localized spot, and loose (or loosening) everywhere else. Well you can't do that anyway, because that would not leave cranks 180=C2=B0 apart as they should be. Oi, bloody hell! Please, not the Q-factor thing again! How does how convexly tapered pegs in squarely tapered holes fit, do with crank spacing anyways? Sometimes metal components should have some leeway between them. Other times, they shouldn't. And the only reason to "lubricate" cotter pins (w/ appropriate grease) is to be able to easily pop them out in order to service the BB. They don't fail from inadequate greasing. Might bend the threaded section when driving them out, but that goes with the territory. And there's an acquirable "touch" for avoiding that. Well, it's mostly luck. That's the classic demise of cotters. That is why one doesn't extract them without a pair of new ones in the event of a squashed thread. Ones that actually & properly fit in the first place. cheers, Tom -- Nothing is safe from me. I'm really at: tkeats curlicue vcn dot bc dot ca |
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