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#31
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DIY Bottom Bracket Spindle
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#32
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DIY Bottom Bracket Spindle
On Wed, 05 Feb 2014 13:28:06 GMT, Ralph Barone
wrote: wrote: ? use a cartridge bearing ! or oak and tallow with leather seals. Now THAT would be an interesting design exercise. In the 1960's I made a lignum Vitae bearing for a 10 inch propeller shaft. It does work :-) -- Cheers, John B. |
#33
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DIY Bottom Bracket Spindle
John B. wrote:
On Wed, 05 Feb 2014 13:28:06 GMT, Ralph Barone wrote: wrote: ? use a cartridge bearing ! or oak and tallow with leather seals. Now THAT would be an interesting design exercise. In the 1960's I made a lignum Vitae bearing for a 10 inch propeller shaft. It does work :-) I was imagining oak half shafts in a bamboo axle tube and trying to imagine the bearing design for that which would withstand radial and axial loads. |
#34
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DIY Bottom Bracket Spindle
James wrote:
On 06/02/14 00:45, Ralph Barone wrote: Frank Krygowski wrote: On Tuesday, February 4, 2014 11:31:45 PM UTC-5, Ralph Barone wrote: The big problem I have here is estimating the loads. Assuming 150 lbs on the back end, static radial load is approx 75 lbs each on the outer bearings and half of max chain tension on each of the inners. Assuming 0.5 g max cornering and popping up on one wheel, the max axial load is 75 lbs (or less if you're an optimist and assume that both bearings on an axle share the axial load. However, I don't have a handle on dynamic loading. What's the multiplier for going off a curb (either up or down)? Hitting a big rock in mid-turn? I think the only type of person who could reliably give you that multiplier would be a person who had successful experience designing similar machines. Maybe your best bet would be to examine prior art. Find a trike that's similar to what you have in mind, and find out what they're using for bearings. They may be plain old cup & cone bearings, but if you get information on the number and size of balls, plus the diameter of the races, you can probably find an angular contact bearing with similar features. It's also worth remembering that if you under-size a ball bearing, it rarely causes a catastrophe. Usually, it just gives you a lower than expected life. For most unusual bikes, I don't think that would be a big deal, unless you're way, way off! - Frank Krygowski Well, if this paper is to be believed, 40 g's is a reasonable number to use. It seems high, though. I suspect when converting that acceleration to a force, I would have to be somewhat selective in what mass I choose to use (ie: the bike by itself vs. bike plus rider). http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34273/OrendurffMichael1997.pdf?sequence=1 Why not use a bearing that's a bit larger than regular bike wheel bearings? My wheel hubs have a 6001 bearings... http://www.vxb.com/page/bearings/PRO...FYnjpAodz0AAxA So go for something a bit bigger than that perhaps? It's looking like a type 1623 bearing might be as good as I can get. 5/8" ID, 1 3/8" OD, about 700 lb static radial load rating (so maybe 175 to 350 lb axial load rating). Interestingly enough, I can't seem to find a 3/4" ID, 1 3/8 OD bearing. I guess there's not enough room left to stuff the balls in. |
#35
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DIY Bottom Bracket Spindle
On Thu, 06 Feb 2014 02:33:52 GMT, Ralph Barone
wrote: John B. wrote: On Wed, 05 Feb 2014 13:28:06 GMT, Ralph Barone wrote: wrote: ? use a cartridge bearing ! or oak and tallow with leather seals. Now THAT would be an interesting design exercise. In the 1960's I made a lignum Vitae bearing for a 10 inch propeller shaft. It does work :-) I was imagining oak half shafts in a bamboo axle tube and trying to imagine the bearing design for that which would withstand radial and axial loads. My God! Be modern! By the 1800's most wagons had shifted to steel axles and wooden bearings :-) No reason to stick with the wooden axles. -- Cheers, John B. |
#36
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DIY Bottom Bracket Spindle
bamboo isnot wood. bamboo fibers are bundled without much cellulose binding. more weedy without the water content.
A large diameter oak axle for a single wheel under light load would last 2-300 miles if the grease was clean. How far could you go? |
#37
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DIY Bottom Bracket Spindle
Ralph Barone wrote:
James wrote: On 06/02/14 00:45, Ralph Barone wrote: Frank Krygowski wrote: On Tuesday, February 4, 2014 11:31:45 PM UTC-5, Ralph Barone wrote: The big problem I have here is estimating the loads. Assuming 150 lbs on the back end, static radial load is approx 75 lbs each on the outer bearings and half of max chain tension on each of the inners. Assuming 0.5 g max cornering and popping up on one wheel, the max axial load is 75 lbs (or less if you're an optimist and assume that both bearings on an axle share the axial load. However, I don't have a handle on dynamic loading. What's the multiplier for going off a curb (either up or down)? Hitting a big rock in mid-turn? I think the only type of person who could reliably give you that multiplier would be a person who had successful experience designing similar machines. Maybe your best bet would be to examine prior art. Find a trike that's similar to what you have in mind, and find out what they're using for bearings. They may be plain old cup & cone bearings, but if you get information on the number and size of balls, plus the diameter of the races, you can probably find an angular contact bearing with similar features. It's also worth remembering that if you under-size a ball bearing, it rarely causes a catastrophe. Usually, it just gives you a lower than expected life. For most unusual bikes, I don't think that would be a big deal, unless you're way, way off! - Frank Krygowski Well, if this paper is to be believed, 40 g's is a reasonable number to use. It seems high, though. I suspect when converting that acceleration to a force, I would have to be somewhat selective in what mass I choose to use (ie: the bike by itself vs. bike plus rider). http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34273/OrendurffMichael1997.pdf?sequence=1 Why not use a bearing that's a bit larger than regular bike wheel bearings? My wheel hubs have a 6001 bearings... http://www.vxb.com/page/bearings/PRO...FYnjpAodz0AAxA So go for something a bit bigger than that perhaps? It's looking like a type 1623 bearing might be as good as I can get. 5/8" ID, 1 3/8" OD, about 700 lb static radial load rating (so maybe 175 to 350 lb axial load rating). Interestingly enough, I can't seem to find a 3/4" ID, 1 3/8 OD bearing. I guess there's not enough room left to stuff the balls in. Well, it seems that all that remains is to reconcile the fact that you can't cut a 1.375x24 tpi thread in a tube with a 1.375" ID and I might have a design. Thank you everyone. |
#38
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DIY Bottom Bracket Spindle
On 2/6/2014 7:27 AM, Ralph Barone wrote:
Ralph Barone wrote: James wrote: On 06/02/14 00:45, Ralph Barone wrote: Frank Krygowski wrote: On Tuesday, February 4, 2014 11:31:45 PM UTC-5, Ralph Barone wrote: The big problem I have here is estimating the loads. Assuming 150 lbs on the back end, static radial load is approx 75 lbs each on the outer bearings and half of max chain tension on each of the inners. Assuming 0.5 g max cornering and popping up on one wheel, the max axial load is 75 lbs (or less if you're an optimist and assume that both bearings on an axle share the axial load. However, I don't have a handle on dynamic loading. What's the multiplier for going off a curb (either up or down)? Hitting a big rock in mid-turn? I think the only type of person who could reliably give you that multiplier would be a person who had successful experience designing similar machines. Maybe your best bet would be to examine prior art. Find a trike that's similar to what you have in mind, and find out what they're using for bearings. They may be plain old cup & cone bearings, but if you get information on the number and size of balls, plus the diameter of the races, you can probably find an angular contact bearing with similar features. It's also worth remembering that if you under-size a ball bearing, it rarely causes a catastrophe. Usually, it just gives you a lower than expected life. For most unusual bikes, I don't think that would be a big deal, unless you're way, way off! - Frank Krygowski Well, if this paper is to be believed, 40 g's is a reasonable number to use. It seems high, though. I suspect when converting that acceleration to a force, I would have to be somewhat selective in what mass I choose to use (ie: the bike by itself vs. bike plus rider). http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34273/OrendurffMichael1997.pdf?sequence=1 Why not use a bearing that's a bit larger than regular bike wheel bearings? My wheel hubs have a 6001 bearings... http://www.vxb.com/page/bearings/PRO...FYnjpAodz0AAxA So go for something a bit bigger than that perhaps? It's looking like a type 1623 bearing might be as good as I can get. 5/8" ID, 1 3/8" OD, about 700 lb static radial load rating (so maybe 175 to 350 lb axial load rating). Interestingly enough, I can't seem to find a 3/4" ID, 1 3/8 OD bearing. I guess there's not enough room left to stuff the balls in. Well, it seems that all that remains is to reconcile the fact that you can't cut a 1.375x24 tpi thread in a tube with a 1.375" ID and I might have a design. Thank you everyone. Right but if everything else is suitable you could turn the thread off and just press the cup into the tube. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#39
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DIY Bottom Bracket Spindle
In article , AMuzi
wrote: On 2/6/2014 7:27 AM, Ralph Barone wrote: Ralph Barone wrote: James wrote: On 06/02/14 00:45, Ralph Barone wrote: Frank Krygowski wrote: On Tuesday, February 4, 2014 11:31:45 PM UTC-5, Ralph Barone wrote: The big problem I have here is estimating the loads. Assuming 150 lbs on the back end, static radial load is approx 75 lbs each on the outer bearings and half of max chain tension on each of the inners. Assuming 0.5 g max cornering and popping up on one wheel, the max axial load is 75 lbs (or less if you're an optimist and assume that both bearings on an axle share the axial load. However, I don't have a handle on dynamic loading. What's the multiplier for going off a curb (either up or down)? Hitting a big rock in mid-turn? I think the only type of person who could reliably give you that multiplier would be a person who had successful experience designing similar machines. Maybe your best bet would be to examine prior art. Find a trike that's similar to what you have in mind, and find out what they're using for bearings. They may be plain old cup & cone bearings, but if you get information on the number and size of balls, plus the diameter of the races, you can probably find an angular contact bearing with similar features. It's also worth remembering that if you under-size a ball bearing, it rarely causes a catastrophe. Usually, it just gives you a lower than expected life. For most unusual bikes, I don't think that would be a big deal, unless you're way, way off! - Frank Krygowski Well, if this paper is to be believed, 40 g's is a reasonable number to use. It seems high, though. I suspect when converting that acceleration to a force, I would have to be somewhat selective in what mass I choose to use (ie: the bike by itself vs. bike plus rider). http://ir.library.oregonstate.edu/xm...957/34273/Oren durffMichael1997.pdf?sequence=1 Why not use a bearing that's a bit larger than regular bike wheel bearings? My wheel hubs have a 6001 bearings... http://www.vxb.com/page/bearings/PRO...rwCFYnjpAodz0A AxA So go for something a bit bigger than that perhaps? It's looking like a type 1623 bearing might be as good as I can get. 5/8" ID, 1 3/8" OD, about 700 lb static radial load rating (so maybe 175 to 350 lb axial load rating). Interestingly enough, I can't seem to find a 3/4" ID, 1 3/8 OD bearing. I guess there's not enough room left to stuff the balls in. Well, it seems that all that remains is to reconcile the fact that you can't cut a 1.375x24 tpi thread in a tube with a 1.375" ID and I might have a design. Thank you everyone. Right but if everything else is suitable you could turn the thread off and just press the cup into the tube. The reason I had chosen to put bottom bracket cups in the design was not to hold the bearings radially (ie: put the bearing inside the cup), but to give me a means to adjust the axial slop in the system and allow me to fine tune the axle position wrt the diff. It turned out that old style bottom bracket cups were the cheapest part that came readily to mind to do that, so the thread is the important bit for me. I really should try and put together an ASCII-CAD drawing of what I have/had in mind. |
#40
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DIY Bottom Bracket Spindle
In article invalid-D9B8AE.06353206022014@shawnews,
Ralph Barone wrote: In article , AMuzi wrote: On 2/6/2014 7:27 AM, Ralph Barone wrote: Ralph Barone wrote: James wrote: On 06/02/14 00:45, Ralph Barone wrote: Frank Krygowski wrote: On Tuesday, February 4, 2014 11:31:45 PM UTC-5, Ralph Barone wrote: The big problem I have here is estimating the loads. Assuming 150 lbs on the back end, static radial load is approx 75 lbs each on the outer bearings and half of max chain tension on each of the inners. Assuming 0.5 g max cornering and popping up on one wheel, the max axial load is 75 lbs (or less if you're an optimist and assume that both bearings on an axle share the axial load. However, I don't have a handle on dynamic loading. What's the multiplier for going off a curb (either up or down)? Hitting a big rock in mid-turn? I think the only type of person who could reliably give you that multiplier would be a person who had successful experience designing similar machines. Maybe your best bet would be to examine prior art. Find a trike that's similar to what you have in mind, and find out what they're using for bearings. They may be plain old cup & cone bearings, but if you get information on the number and size of balls, plus the diameter of the races, you can probably find an angular contact bearing with similar features. It's also worth remembering that if you under-size a ball bearing, it rarely causes a catastrophe. Usually, it just gives you a lower than expected life. For most unusual bikes, I don't think that would be a big deal, unless you're way, way off! - Frank Krygowski Well, if this paper is to be believed, 40 g's is a reasonable number to use. It seems high, though. I suspect when converting that acceleration to a force, I would have to be somewhat selective in what mass I choose to use (ie: the bike by itself vs. bike plus rider). http://ir.library.oregonstate.edu/xm.../1957/34273/Or en durffMichael1997.pdf?sequence=1 Why not use a bearing that's a bit larger than regular bike wheel bearings? My wheel hubs have a 6001 bearings... http://www.vxb.com/page/bearings/PRO...HtrwCFYnjpAodz 0A AxA So go for something a bit bigger than that perhaps? It's looking like a type 1623 bearing might be as good as I can get. 5/8" ID, 1 3/8" OD, about 700 lb static radial load rating (so maybe 175 to 350 lb axial load rating). Interestingly enough, I can't seem to find a 3/4" ID, 1 3/8 OD bearing. I guess there's not enough room left to stuff the balls in. Well, it seems that all that remains is to reconcile the fact that you can't cut a 1.375x24 tpi thread in a tube with a 1.375" ID and I might have a design. Thank you everyone. Right but if everything else is suitable you could turn the thread off and just press the cup into the tube. The reason I had chosen to put bottom bracket cups in the design was not to hold the bearings radially (ie: put the bearing inside the cup), but to give me a means to adjust the axial slop in the system and allow me to fine tune the axle position wrt the diff. It turned out that old style bottom bracket cups were the cheapest part that came readily to mind to do that, so the thread is the important bit for me. I really should try and put together an ASCII-CAD drawing of what I have/had in mind. There... You just can't draw stuff like this on an iPhone. Imagine the exact same hardware on the other side of the axle tube. ----------------------------------------------+ AXLE TUBE | --------------------------------/\/\/\/\/\/\/\| | |/\/\/\/\/\/\/\/\/\/\ | || BB CUP | | |+----------------+ | +------+|BEARING | | | |COLLET|| | +__+ | || | --------------+------+--------------------------------------------+ | -- TO DIFF AXLE TO HUB-- | | --------------+------+--------------------------------------------+ | || | | || | +--+ +------+| | | | | |+----------------+ | | || | | |\/\/\/\/\/\/\/\/\/\/ --------------------------------\/\/\/\/\/\/\/| | ----------------------------------------------+ The collets lock to the axle shaft. I figure this is a minimal parts design that allows fine adjustment of axle position as well as bearing preload but doesn't use any weird parts or require any custom machining. Any suggestions on improvements or simplifications are certainly welcome. |
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