|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
two odd wheel-building techniques
While snuffling around the internet, I found this page,
which has links to two pictures that show what seem like unusual wheel-building details: http://www.spokeswagon.com/spokeswag...m&pg=tradition or http://tinyurl.com/4tx6h Click on the blue words in : The builder adjusts spoke line and may add washers between the spoke head and hub flange to limit movement within the hub hole." Then click on the blue words in: The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned . . . Are the washers and the punch common wheel-building techniques, snake-oil, or what? Carl Fogel |
Ads |
#3
|
|||
|
|||
wrote:
While snuffling around the internet, I found this page, which has links to two pictures that show what seem like unusual wheel-building details: http://www.spokeswagon.com/spokeswag...m&pg=tradition or http://tinyurl.com/4tx6h Click on the blue words in : The builder adjusts spoke line and may add washers between the spoke head and hub flange to limit movement within the hub hole." Then click on the blue words in: The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned . . . Are the washers and the punch common wheel-building techniques, snake-oil, or what? The punch is snake oil, and can actually damage the flange if over done. There is some utility to spoke head washers, but only in certain circumstances, and not in the way the web page suggests. If the flange is unusually thin, or the bent portion of the spoke unusually long, a washer (or two) can pull the elbow in closer to the flange, supporting the elbow more evenly. Also, if the spoke holes are unusually large, a washer (or two) can fill in some space, to support the head a bit more evenly. For a flange/hole/spoke combination that is well matched (for example, current Shimano or Campagnolo hubs and DT spokes), there is no need to use washers. A few years ago, DT increased the elbow length on their spokes. To seat the elbow against the flange well, many wheel builders resorted to using spoke head washers. After many complaints from their customers, DT went back to an elbow length very close to their previous length, and spoke head washers have generally not been required for recently produced spokes. (Unfortunately, there are probably some of the old long-elbow stock still floating around.) The idea that spokes "work harden and break" in use is a common misconception by those who do not understand metal fatigue. It is unfortunately common that the mechanisms of wheel failure are not understood by wheelbuilding "experts". Take for example this other nugget of wisdom in the web page: "Machines also do a poor job at sufficiently 'stress relieving' the wheel to remove spoke wind up." Mark McMaster |
#4
|
|||
|
|||
On Sat, 21 Aug 2004 16:02:08 -0600, wrote:
The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned . . . Are the washers and the punch common wheel-building techniques, snake-oil, or what? Unless there is a gross mis-match in the diameters of the holes in the hubshell and the spokes inserted therein, such measures are described by "To gild refined gold, to paint the lily, To throw a perfume on the violet, To smooth the ice, or add another hue Unto the rainbow, or with taper-light To seek the beauteous eye of heaven to garnish, Is wasteful and ridiculous excess." King John. Act iv. Sc. 2. Edward de Vere ------------------------------- John Dacey Business Cycles, Miami, Florida http://www.businesscycles.com Since 1983 Our catalog of track equipment: online since 1996 ------------------------------- |
#5
|
|||
|
|||
On Sat, 21 Aug 2004 19:21:33 -0400, John Dacey
wrote: On Sat, 21 Aug 2004 16:02:08 -0600, wrote: The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned . . . Are the washers and the punch common wheel-building techniques, snake-oil, or what? Unless there is a gross mis-match in the diameters of the holes in the hubshell and the spokes inserted therein, such measures are described by "To gild refined gold, to paint the lily, To throw a perfume on the violet, To smooth the ice, or add another hue Unto the rainbow, or with taper-light To seek the beauteous eye of heaven to garnish, Is wasteful and ridiculous excess." King John. Act iv. Sc. 2. Edward de Vere ------------------------------- John Dacey Dear Eddie, Nonsense--anyone can see that you're actually Izaak Walton. George B. Shaw |
#6
|
|||
|
|||
Carl Fogel writes:
While snuffling around the internet, I found this page, which has links to two pictures that show what seem like unusual wheel-building details: http://tinyurl.com/4tx6h Click on the blue words in : "The builder adjusts spoke line and may add washers between the spoke head and hub flange to limit movement within the hub hole." That may sound good but spoke elbows don't move once the spoke is tensioned. The only effective change washers makes is that of a shorter elbow or a thicker flange. The reason we saw, and maybe still see, spokes with too long an elbow is that machine lacing is difficult with spokes with ideal length elbow and flanges with ideal size spoke holes, both of which are scarce these days, the biggest consumers of these products are machine built wheels they request these poor fits. Then click on the blue words in: The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned... Well that's bogus. Spoke will not work harden in use although they may fail from fatigue. I think it's old mechanics jargon and myth and lore from the days when fatigue failures were routinely attributed to "look the axle crystallized and broke here" when in fact a fatigue failure always exposes the crystal structure because it is inter-grain boundaries that fail most easily in a metal. Are the washers and the punch common wheel-building techniques, snake-oil, or what? As I said, they are a crutch for long elbow spokes or too thin a flange. Jobst Brandt |
#7
|
|||
|
|||
wrote:
Carl Fogel writes: While snuffling around the internet, I found this page, which has links to two pictures that show what seem like unusual wheel-building details: http://tinyurl.com/4tx6h Click on the blue words in : "The builder adjusts spoke line and may add washers between the spoke head and hub flange to limit movement within the hub hole." That may sound good but spoke elbows don't move once the spoke is tensioned. sorry, that's not true. the fact that spokes fatigue at this point is proof. spokes my not move in a readily visible way, just as a fatigued crank spindle may not "move" in a readily visible way, but the very existance of fatigue is as good an evidence of "movement" as you'll ever get. The only effective change washers makes is that of a shorter elbow or a thicker flange. The reason we saw, and maybe still see, spokes with too long an elbow is that machine lacing is difficult with spokes with ideal length elbow and flanges with ideal size spoke holes, both of which are scarce these days, the biggest consumers of these products are machine built wheels they request these poor fits. Then click on the blue words in: The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned... Well that's bogus. Spoke will not work harden in use although they may fail from fatigue. I think it's old mechanics jargon and myth and lore from the days when fatigue failures were routinely attributed to "look the axle crystallized and broke here" when in fact a fatigue failure always exposes the crystal structure because it is inter-grain boundaries that fail most easily in a metal. Are the washers and the punch common wheel-building techniques, snake-oil, or what? As I said, they are a crutch for long elbow spokes or too thin a flange. Jobst Brandt |
#8
|
|||
|
|||
Mark McMaster wrote in message ... The idea that spokes "work harden and break" in use is a common misconception by those who do not understand metal fatigue. It is unfortunately common that the mechanisms of wheel failure are not understood by wheelbuilding "experts". Take for example this other nugget of wisdom in the web page: Please explain how a spoke subjected to a rocking motion eventually fails due to fatigue, preferably in ten words. Trevor |
#9
|
|||
|
|||
Wrote: While snuffling around the internet, I found this page, which has links to two pictures that show what seem like unusual wheel-building details: http://tinyurl.com/4tx6h or http://tinyurl.com/4tx6h Click on the blue words in : The builder adjusts spoke line and may add washers between the spoke head and hub flange to limit movement within the hub hole." Then click on the blue words in: The more stable the elbow within the hub hole the less likely it will "work harden" and break, a common cause of spoke failure. Using a special punch, the builder sets the spoke head in the hub hole to assure it is well seated and won't move when the wheel is tensioned . . . Are the washers and the punch common wheel-building techniques, snake-oil, or what? Carl Fogel "Why do spokes break? Spokes always break as the result of an irregularity in the whee spider. Cause 1 Play between the hub and the spoke. Each spoke is subjected to one loa cycle (loading/unloading) during each complete rotation of the wheel. Each spoke in a bicycle wheel that has been ridden over 2000 km, fo example, has experienced one million load changes. If there is even the slightest play between the spoke and the hu flange, a broken spoke is just a question of time. The spok continually jerks back and forth in the flange, which subjects th spoke elbow to massive stress. This causes the material to becom brittle, the spoke can no longer bear the load and breaks at the elbow Remedy Place washers underneath the head of any spoke where play is felt a the hub flange. " Above quoted from the FAQ section of DT Swiss "Hub hole suitability Hold the hub flange horizontally. Put the spoke with the head inside, a little higher. While centring, you should pus on the hub lightly; the spokes will easily adjust themselves (Attention: do not push so hard that the spokes bend!). Using oversized hub holes is an easy solution. However, this will caus a lot of play and is not recommended. Consider the use of spoke washers Too much tension on the spoke head will also cause problems. Ideal hub hole Ø equals spoke thread Ø + 0.1 mm (eg. spoke thread o 14G/2 mm measures thread 2.25 mm + 0.1 = 2.35 mm: max. hole Ø 2.5 mm)." Above quoted from the "checklist" section of Sapim's site. The thickness (from 2.0 to 4.0 mm on samples I have measured) of th flange and spoke hole size help in determining the use of spoke hea washers. Also, there are at least 3 different spoke head to elbo dimension on DT spokes varying at least .85 mm from shortest t longest. Since, there are these differences and differences in hu flange thicknesses and spoke hole diameters as well as spoke diameter at the hub end; you must make some accomodation for these differences. I will disagree with Jobst's statement that once a spoke is tensione it's elbow doesn't move. I move them by laterally,torsionally, and radially loading the wheel. I minimize the movement by spoke alignment and proper tensioning. I also use spoke head washers and setting techniques to minimize th movement. And to Mark's comment on " The punch is snake oil, and can actuall damage the flange if over done." .... yes you could do damage to the flange if it is ovedone, but don't think we are talking about holding the hub in a vise or on a anvil while hitting the puch with a metal hammer. I give the spok heads a solid strike with a properly aligned puch fron the blow of plastic headed hammer. I have yet to find a hub with too small a hole to fit the roll threade end (2.25 mm) of a 14 g spoke through. I have yet to find a hub where the flange is too thick.... even the 4. mm ones from Phil Wood. I still don't think there is snake oil or even linseed oil involve here -- daveornee |
#10
|
|||
|
|||
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Spoke 'wind-up' question | Dan Daniel | Techniques | 143 | September 3rd 04 06:16 PM |
Building a Spox wheel with regular rim | Michael Press | Techniques | 4 | February 13th 04 02:41 PM |
Who Dumped My Wheel Building Thread Into The Spam Bin? | jagur | Unicycling | 26 | November 8th 03 04:54 PM |
Question about building a custom 4 wheel bike | Randal Lovelace | Recumbent Biking | 3 | October 4th 03 09:18 AM |