Pedal threads tapered?
06-10-17, 11:35 AM
#26
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As stated prior, I've been running Eldi (and some other brand they had at the co-op) all the way down in cranks to do French to standard conversions for many years now, and never had a problem......ever.
06-10-17, 11:52 AM
#27
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Calipers are not suited to measuring threads. To truly measure the aspect of external threads that matters, you need to use a micrometer and you cannot simply measure the major diameter, but must employ a special technique such as measuring over precision wires placed in the thread grooves.
Try this on the pedals, and try it on the largest portion of the taps. Then compare to thread fit standards applicable to the size, usage, and materials in question.
Try this on the pedals, and try it on the largest portion of the taps. Then compare to thread fit standards applicable to the size, usage, and materials in question.
06-10-17, 11:57 AM
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The other problem with measuring major diameter (on a fitting) is that thread forms are usually rounded a bit at the crest, rather than coming to a point. The point isn't meaningful - the diameter of the slopes is.
06-10-17, 12:42 PM
#29
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A tapered major diameter on a tap doesn't indicate the the thread is tapered, it may just indicate that the part of the tap you are measuring isn't the part intended to cut the full major diameter.
The other problem with measuring major diameter (on a fitting) is that thread forms are usually rounded a bit at the crest, rather than coming to a point. The point isn't meaningful - the diameter of the slopes is.
The other problem with measuring major diameter (on a fitting) is that thread forms are usually rounded a bit at the crest, rather than coming to a point. The point isn't meaningful - the diameter of the slopes is.
06-10-17, 12:44 PM
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From Unicris....... "Try this on the pedals, and try it on the largest portion of the taps. Then compare to thread fit standards applicable to the size, usage, and materials in question."
quit quoting things you found on the internet, and measure a tap some time.
now... why would a machinist measure a thread in that manner? answer in your words, not with a quote.
and... how many bike mechanics would need, or even WANT to measure a thread in that manner? And how many possess the gauge wires( or specific thread measuring micrometers,) to measure a thread in that manner?
you "LOOSE" credibility as an educated human by misspelling such a common word, troll boy.
measure the tap in more than one place, if you even own the pedal thread tap set... get back to me with your results... OR take the words of more than one person that has done so, ok?
thanks for the laughs, btw.
quit quoting things you found on the internet, and measure a tap some time.
now... why would a machinist measure a thread in that manner? answer in your words, not with a quote.
and... how many bike mechanics would need, or even WANT to measure a thread in that manner? And how many possess the gauge wires( or specific thread measuring micrometers,) to measure a thread in that manner?
you "LOOSE" credibility as an educated human by misspelling such a common word, troll boy.
measure the tap in more than one place, if you even own the pedal thread tap set... get back to me with your results... OR take the words of more than one person that has done so, ok?
thanks for the laughs, btw.
Last edited by maddog34; 06-10-17 at 12:50 PM.
06-10-17, 01:11 PM
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Of course a tapered tap will measure tapered by most methods.
The point is that a tap for a non-tapered thread can also measure tapered when measured by an unreliable method or when measuring a part of the tap that is not intended to cut the finished thread form.
The key question is if an accurate means of measuring of the largest part of the tap indicates that it will cut threads that exceed the specification plus normal fit class allowance.
06-10-17, 01:14 PM
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Because - apparently unlike you - they know that the other ways of measuring a thread are unreliable as they measure something that can have a lot of unimportant variation, and don't measure the thing that actually matters.
You were the one who proposed measuring to prove your point - but you proposed doing so in an unreliable way. Someone with actual experience of the authority you are trying to claim would not make such a beginner mistake - that is, unless they were talking down to their audience and hoping to make their point by intimidation, rather than to propose an actually meaningful test.
If you want to make an argument for your theory, make a sound one - otherwise expect to be called on the error of the argument, which is independent of the actual truth or falsehood of the theory.
and... how many bike mechanics would need, or even WANT to measure a thread in that manner?
If you want to make an argument for your theory, make a sound one - otherwise expect to be called on the error of the argument, which is independent of the actual truth or falsehood of the theory.
Last edited by UniChris; 06-10-17 at 01:41 PM.
06-10-17, 02:54 PM
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Because - apparently unlike you - they know that the other ways of measuring a thread are unreliable as they measure something that can have a lot of unimportant variation, and don't measure the thing that actually matters.
You were the one who proposed measuring to prove your point - but you proposed doing so in an unreliable way. Someone with actual experience of the authority you are trying to claim would not make such a beginner mistake - that is, unless they were talking down to their audience and hoping to make their point by intimidation, rather than to propose an actually meaningful test.
If you want to make an argument for your theory, make a sound one - otherwise expect to be called on the error of the argument, which is independent of the actual truth or falsehood of the theory.
You were the one who proposed measuring to prove your point - but you proposed doing so in an unreliable way. Someone with actual experience of the authority you are trying to claim would not make such a beginner mistake - that is, unless they were talking down to their audience and hoping to make their point by intimidation, rather than to propose an actually meaningful test.
If you want to make an argument for your theory, make a sound one - otherwise expect to be called on the error of the argument, which is independent of the actual truth or falsehood of the theory.
measure away... report your findings, troll. Or would that blow a hole in your pathetic trolling?
06-10-17, 03:05 PM
#34
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Given that I haven't stated a position on pedal threads being tapered or not, I have nothing to prove.
What I have pointed out is that your arguments in favor of the idea are bunk. If you want to use measurement to prove a point, you'll need to take some valid ones.
Or you can just call people irrelevant names - but doing so won't win your argument with those who (unlike me) actually did state a disagreement with you on the taper claim.
What I have pointed out is that your arguments in favor of the idea are bunk. If you want to use measurement to prove a point, you'll need to take some valid ones.
Or you can just call people irrelevant names - but doing so won't win your argument with those who (unlike me) actually did state a disagreement with you on the taper claim.
Last edited by UniChris; 06-10-17 at 03:11 PM.
06-10-17, 03:10 PM
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Given that I haven't stated a position on pedal threads being tapered or not, I have nothing to prove.
What I have pointed out is that your arguments in favor of the idea are bunk. If you want to use measurement to prove a point, you'll need to take some valid ones.
Or you can just call people irrelevant names - but doing so won't win your argument with those who (unlike me) actually did disagree with you on the taper claim.
What I have pointed out is that your arguments in favor of the idea are bunk. If you want to use measurement to prove a point, you'll need to take some valid ones.
Or you can just call people irrelevant names - but doing so won't win your argument with those who (unlike me) actually did disagree with you on the taper claim.
TROLL away.
06-10-17, 03:10 PM
#36
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Faulty logic.
Of course a tapered tap will measure tapered by most methods.
The point is that a tap for a non-tapered thread can also measure tapered when measured by an unreliable method or when measuring a part of the tap that is not intended to cut the finished thread form.
The key question is if an accurate means of measuring of the largest part of the tap indicates that it will cut threads that exceed the specification plus normal fit class allowance.
Of course a tapered tap will measure tapered by most methods.
The point is that a tap for a non-tapered thread can also measure tapered when measured by an unreliable method or when measuring a part of the tap that is not intended to cut the finished thread form.
The key question is if an accurate means of measuring of the largest part of the tap indicates that it will cut threads that exceed the specification plus normal fit class allowance.
06-10-17, 03:25 PM
#37
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As referenced earlier in this thread, the specifications for pedal threads; Bicycle Screw Thread DIN 79012 gives a major diameter of 14.288 MM. The major diameter of the Hozan taps tapers from approx 14MM to 15MM. 15MM appears to exceed the standard of 14.288MM.
It appears the only tapered pedal threads are the Hozan taps. Which are so gradually tapered, they may be nearly functionally straight over the short threaded length of a pedal axle.
For whatever reason, they allow adjusting the diameter of a threaded hole by how deeply they are turned into the crank. I'll assume to allow creating a close fit to any pedal axle. I can't think of any other reason to make a pedal tap that can create threaded holes of varying diameter.
For whatever reason, they allow adjusting the diameter of a threaded hole by how deeply they are turned into the crank. I'll assume to allow creating a close fit to any pedal axle. I can't think of any other reason to make a pedal tap that can create threaded holes of varying diameter.
Last edited by UniChris; 06-10-17 at 03:31 PM.
06-10-17, 03:51 PM
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...there's an aspect in this discussion of attributing a certain degree of precision to pedal and crank threads that probably does not exist in real life. If you've ever installed the threadserts used to repair a stripped crank pedal eye threading, it's pretty obvious that they are stamped formed from some kind of sheet metal. You overbore the hole with the proper tool, and then insert the threadsert using an old pedal spindle (R or L handed as required). They work well, I've never had one fail or pull out.
I presume this is because the pedal you screw into them has a tendency to reform the mating surface a little. Which also happens in a regular alloy crank/steel pedal spindle interface when you thread it in and torque it tight.
But if the Hozan tap is as oversized at the butt end as you say it is (I've not measured), I imagine I'll find out quickly in my experiment.
...there's an aspect in this discussion of attributing a certain degree of precision to pedal and crank threads that probably does not exist in real life. If you've ever installed the threadserts used to repair a stripped crank pedal eye threading, it's pretty obvious that they are stamped formed from some kind of sheet metal. You overbore the hole with the proper tool, and then insert the threadsert using an old pedal spindle (R or L handed as required). They work well, I've never had one fail or pull out.
I presume this is because the pedal you screw into them has a tendency to reform the mating surface a little. Which also happens in a regular alloy crank/steel pedal spindle interface when you thread it in and torque it tight.
But if the Hozan tap is as oversized at the butt end as you say it is (I've not measured), I imagine I'll find out quickly in my experiment.
06-10-17, 04:22 PM
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Wow, how did I miss this thread? As a quality engineer in CNC machining, let me tell you'se a few things:
What the OP was seeing is called "lead in", which is a certain amount of taper at the ends of essentially all taps. This varies from tap to tap. What it does is guarantees that several rows of the tap are cutting, Instead of just the first row, which would wear out very quickly. Speed taps (those with less lead in and 4 cutting edges) can be used where a better pre-drilling has been done (and are risky to use by hand...), but generally a regular tap has only 2 cutting edges, and a significant taper at the ends.
And, as for the measuring over pins, a pitch mic is a LOT easier to use, but in the end, tap pitch Ø's are NOT the same as the final bolt pitch Ø will be!
What the OP was seeing is called "lead in", which is a certain amount of taper at the ends of essentially all taps. This varies from tap to tap. What it does is guarantees that several rows of the tap are cutting, Instead of just the first row, which would wear out very quickly. Speed taps (those with less lead in and 4 cutting edges) can be used where a better pre-drilling has been done (and are risky to use by hand...), but generally a regular tap has only 2 cutting edges, and a significant taper at the ends.
And, as for the measuring over pins, a pitch mic is a LOT easier to use, but in the end, tap pitch Ø's are NOT the same as the final bolt pitch Ø will be!
06-10-17, 04:36 PM
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You two gentlemen who have been AT each other lately . . . why don't we take a break and calm down before any unnecessary hostilities get started. Thanks! 
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06-10-17, 05:09 PM
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...maybe we could digress into the best thing to use on pedal threads when you install them. That always goes really well.
...maybe we could digress into the best thing to use on pedal threads when you install them. That always goes really well.
06-10-17, 05:13 PM
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WD40? 
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06-10-17, 05:22 PM
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06-10-17, 07:01 PM
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Wow, how did I miss this thread? As a quality engineer in CNC machining, let me tell you'se a few things:
What the OP was seeing is called "lead in", which is a certain amount of taper at the ends of essentially all taps. This varies from tap to tap. What it does is guarantees that several rows of the tap are cutting, Instead of just the first row, which would wear out very quickly. Speed taps (those with less lead in and 4 cutting edges) can be used where a better pre-drilling has been done (and are risky to use by hand...), but generally a regular tap has only 2 cutting edges, and a significant taper at the ends.
And, as for the measuring over pins, a pitch mic is a LOT easier to use, but in the end, tap pitch Ø's are NOT the same as the final bolt pitch Ø will be!
What the OP was seeing is called "lead in", which is a certain amount of taper at the ends of essentially all taps. This varies from tap to tap. What it does is guarantees that several rows of the tap are cutting, Instead of just the first row, which would wear out very quickly. Speed taps (those with less lead in and 4 cutting edges) can be used where a better pre-drilling has been done (and are risky to use by hand...), but generally a regular tap has only 2 cutting edges, and a significant taper at the ends.
And, as for the measuring over pins, a pitch mic is a LOT easier to use, but in the end, tap pitch Ø's are NOT the same as the final bolt pitch Ø will be!
06-10-17, 07:11 PM
#45
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06-10-17, 07:14 PM
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oh... and that tap set that Park sells?... it's meant only for CHASING bunged up threads....
The instructions that came with my Hozan pedal taps say under PRECAUTIONS "These taps are for correcting the threads on bicycle pedals. Do not use for any other purpose."
I'm surprised that since the taps seem to have features for tapping new holes there is this caution. Maybe it is CYA for them never being responsible for any of the threads their tools are used on.
It also says under CAUTION "Do not cut all at once since the threads are tapered. Work gradually checking the fitting of the pedal"
I'm surprised that since the taps seem to have features for tapping new holes there is this caution. Maybe it is CYA for them never being responsible for any of the threads their tools are used on.
It also says under CAUTION "Do not cut all at once since the threads are tapered. Work gradually checking the fitting of the pedal"
And I see you haven't responded to that post yet, I'd like to hear your response.
Pretty sure you're the only one trolling here.
Go ahead, dig yourself deeper into your hole. We're all having a good show watching you do it.
06-10-17, 07:36 PM
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Oh you mean like the one I posted in that last post? The one directly for sale on MSC? Yeah, it was really hard to find. I just googled 9/16-20 tap and that was the first link. Definitely "special order."
Interesting that someone else that owns the tap you do says that they're also only made for correcting threads and are special use only, definitely not to be used for threading new cranks...
And I see you haven't responded to that post yet, I'd like to hear your response.
No response to this either?
Pretty sure you're the only one trolling here.
Go ahead, dig yourself deeper into your hole. We're all having a good show watching you do it.
Interesting that someone else that owns the tap you do says that they're also only made for correcting threads and are special use only, definitely not to be used for threading new cranks...
And I see you haven't responded to that post yet, I'd like to hear your response.
No response to this either?
Pretty sure you're the only one trolling here.
Go ahead, dig yourself deeper into your hole. We're all having a good show watching you do it.
