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higbee ends for threads

AM
Adrian Mariano
Sun, Feb 19, 2023 10:09 PM

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?  I'm trying to figure
out how the higbee ends in BOSL2 should work, and I got some feedback from
an erratic individual who writes once a month that I was doing it all
wrong.  And I think that he was at least partly correct, but without better
communication, I'm having trouble nailing down how to fix the
implementation.

So I'm left with a variety of questions about this topic and haven't had
much luck researching this on line.

  1. What is the ideal way to terminate threads, given that in 3d modeling
    we aren't constrained by machining limitations.  How abruptly should the
    thread end?  Should it taper in width?  In short, what exactly should
    BOSL2 do when producing threads?

  2. What kind of thread ends should a threading library support more
    broadly?  Is one type of end enough?  It seems like thread ends for plastic
    bottles taper in a different way than the patented higbee.

  3. What type of thread endings does the term "higbee" apply to?  The
    original patent refers to "blunt ends" and the modern nomenclature seems to
    be to move away from "higbee" to "blunt start", but my erratic
    correspondent insisted that any thread end where the thread wasn't clipped
    off by the end of the bold was a "higbee" and that the term "higbee" was
    best.

  4. How exactly does the higbee thread prevent cross threading.  How does
    cross threading happen?  I guess this relates back to #1.  When I was
    thinking about it I got a feeling it had to do with a lack of a
    fractionally wide thread, which can more easily engage at a funny angle.
    That would suggest that a thread that tapers in width would be bad, since
    it could suffer the same problem.  Am I right about that?

Is there anybody out there who is an expert in threading with a deep understanding of how thread ends should be formed? I'm trying to figure out how the higbee ends in BOSL2 should work, and I got some feedback from an erratic individual who writes once a month that I was doing it all wrong. And I think that he was at least partly correct, but without better communication, I'm having trouble nailing down how to fix the implementation. So I'm left with a variety of questions about this topic and haven't had much luck researching this on line. 1. What is the ideal way to terminate threads, given that in 3d modeling we aren't constrained by machining limitations. How abruptly should the thread end? Should it taper in width? In short, what exactly should BOSL2 do when producing threads? 2. What kind of thread ends should a threading library support more broadly? Is one type of end enough? It seems like thread ends for plastic bottles taper in a different way than the patented higbee. 3. What type of thread endings does the term "higbee" apply to? The original patent refers to "blunt ends" and the modern nomenclature seems to be to move away from "higbee" to "blunt start", but my erratic correspondent insisted that any thread end where the thread wasn't clipped off by the end of the bold was a "higbee" and that the term "higbee" was best. 4. How exactly does the higbee thread prevent cross threading. How does cross threading happen? I guess this relates back to #1. When I was thinking about it I got a feeling it had to do with a lack of a fractionally wide thread, which can more easily engage at a funny angle. That would suggest that a thread that tapers in width would be bad, since it could suffer the same problem. Am I right about that?
NH
nop head
Sun, Feb 19, 2023 10:37 PM

I am not an expert but I think normal machine screws that you can buy the
thread at the end tapers in diameter, so it sort of follows a chamfer. My
thread library supports that and a simple chamfered end, which is what you
get when you cut a threaded rod and then chamfer the end.

Higbee seems to be cutting off the crests of the leading treads, making
them flat topped. It seems to be a second pass on a CNC lathe that uses a
flat ended grooving tool to remove the sharp crests left by the threading
tool when it meets the chamfer.

On Sun, 19 Feb 2023 at 22:11, Adrian Mariano avm4@cornell.edu wrote:

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?  I'm trying to figure
out how the higbee ends in BOSL2 should work, and I got some feedback from
an erratic individual who writes once a month that I was doing it all
wrong.  And I think that he was at least partly correct, but without better
communication, I'm having trouble nailing down how to fix the
implementation.

So I'm left with a variety of questions about this topic and haven't had
much luck researching this on line.

  1. What is the ideal way to terminate threads, given that in 3d modeling
    we aren't constrained by machining limitations.  How abruptly should the
    thread end?  Should it taper in width?  In short, what exactly should
    BOSL2 do when producing threads?

  2. What kind of thread ends should a threading library support more
    broadly?  Is one type of end enough?  It seems like thread ends for plastic
    bottles taper in a different way than the patented higbee.

  3. What type of thread endings does the term "higbee" apply to?  The
    original patent refers to "blunt ends" and the modern nomenclature seems to
    be to move away from "higbee" to "blunt start", but my erratic
    correspondent insisted that any thread end where the thread wasn't clipped
    off by the end of the bold was a "higbee" and that the term "higbee" was
    best.

  4. How exactly does the higbee thread prevent cross threading.  How does
    cross threading happen?  I guess this relates back to #1.  When I was
    thinking about it I got a feeling it had to do with a lack of a
    fractionally wide thread, which can more easily engage at a funny angle.
    That would suggest that a thread that tapers in width would be bad, since
    it could suffer the same problem.  Am I right about that?


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I am not an expert but I think normal machine screws that you can buy the thread at the end tapers in diameter, so it sort of follows a chamfer. My thread library supports that and a simple chamfered end, which is what you get when you cut a threaded rod and then chamfer the end. Higbee seems to be cutting off the crests of the leading treads, making them flat topped. It seems to be a second pass on a CNC lathe that uses a flat ended grooving tool to remove the sharp crests left by the threading tool when it meets the chamfer. On Sun, 19 Feb 2023 at 22:11, Adrian Mariano <avm4@cornell.edu> wrote: > Is there anybody out there who is an expert in threading with a deep > understanding of how thread ends should be formed? I'm trying to figure > out how the higbee ends in BOSL2 should work, and I got some feedback from > an erratic individual who writes once a month that I was doing it all > wrong. And I think that he was at least partly correct, but without better > communication, I'm having trouble nailing down how to fix the > implementation. > > So I'm left with a variety of questions about this topic and haven't had > much luck researching this on line. > > 1. What is the ideal way to terminate threads, given that in 3d modeling > we aren't constrained by machining limitations. How abruptly should the > thread end? Should it taper in width? In short, what exactly should > BOSL2 do when producing threads? > > 2. What kind of thread ends should a threading library support more > broadly? Is one type of end enough? It seems like thread ends for plastic > bottles taper in a different way than the patented higbee. > > 3. What type of thread endings does the term "higbee" apply to? The > original patent refers to "blunt ends" and the modern nomenclature seems to > be to move away from "higbee" to "blunt start", but my erratic > correspondent insisted that any thread end where the thread wasn't clipped > off by the end of the bold was a "higbee" and that the term "higbee" was > best. > > 4. How exactly does the higbee thread prevent cross threading. How does > cross threading happen? I guess this relates back to #1. When I was > thinking about it I got a feeling it had to do with a lack of a > fractionally wide thread, which can more easily engage at a funny angle. > That would suggest that a thread that tapers in width would be bad, since > it could suffer the same problem. Am I right about that? > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
AM
Adrian Mariano
Sun, Feb 19, 2023 11:06 PM

I think a normal thread is created by tapping the thread onto a rod or into
a hole.  Possibly a chamfer is applied afterwards.  I think this is done
for normal machine screws because it's cheap and fast, not because it is
good.  In the context of 3d printed parts, there is no reason not to choose
the best option, because we aren't paying a machinist.  Furthermore, the
knife-thin edge that arises when you carry threading out to the end of a
rod is probably not the best shape for 3d printing anyway, so why do that?
Maybe the chamfer helps reduce it, but it's not the best solution.  And it
sounds like the chamfer isn't ideal for preventing cross threading.  My
erratic correspondent seemed to think that threads made the "standard" way
were worthless in 3d printed plastic if the parts were going to be
disassembled and reassembled multiple times, though I admit that I don't
understand why.  He seemed to think---possibly based on experience with
failed parts?--- that such threads just wouldn't last, and that the higbee
end is essential.

On Sun, Feb 19, 2023 at 5:39 PM nop head nop.head@gmail.com wrote:

I am not an expert but I think normal machine screws that you can buy the
thread at the end tapers in diameter, so it sort of follows a chamfer. My
thread library supports that and a simple chamfered end, which is what you
get when you cut a threaded rod and then chamfer the end.

Higbee seems to be cutting off the crests of the leading treads, making
them flat topped. It seems to be a second pass on a CNC lathe that uses a
flat ended grooving tool to remove the sharp crests left by the threading
tool when it meets the chamfer.

On Sun, 19 Feb 2023 at 22:11, Adrian Mariano avm4@cornell.edu wrote:

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?  I'm trying to figure
out how the higbee ends in BOSL2 should work, and I got some feedback from
an erratic individual who writes once a month that I was doing it all
wrong.  And I think that he was at least partly correct, but without better
communication, I'm having trouble nailing down how to fix the
implementation.

So I'm left with a variety of questions about this topic and haven't had
much luck researching this on line.

  1. What is the ideal way to terminate threads, given that in 3d modeling
    we aren't constrained by machining limitations.  How abruptly should the
    thread end?  Should it taper in width?  In short, what exactly should
    BOSL2 do when producing threads?

  2. What kind of thread ends should a threading library support more
    broadly?  Is one type of end enough?  It seems like thread ends for plastic
    bottles taper in a different way than the patented higbee.

  3. What type of thread endings does the term "higbee" apply to?  The
    original patent refers to "blunt ends" and the modern nomenclature seems to
    be to move away from "higbee" to "blunt start", but my erratic
    correspondent insisted that any thread end where the thread wasn't clipped
    off by the end of the bold was a "higbee" and that the term "higbee" was
    best.

  4. How exactly does the higbee thread prevent cross threading.  How does
    cross threading happen?  I guess this relates back to #1.  When I was
    thinking about it I got a feeling it had to do with a lack of a
    fractionally wide thread, which can more easily engage at a funny angle.
    That would suggest that a thread that tapers in width would be bad, since
    it could suffer the same problem.  Am I right about that?


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To unsubscribe send an email to discuss-leave@lists.openscad.org


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To unsubscribe send an email to discuss-leave@lists.openscad.org

I think a normal thread is created by tapping the thread onto a rod or into a hole. Possibly a chamfer is applied afterwards. I think this is done for normal machine screws because it's cheap and fast, not because it is good. In the context of 3d printed parts, there is no reason not to choose the best option, because we aren't paying a machinist. Furthermore, the knife-thin edge that arises when you carry threading out to the end of a rod is probably not the best shape for 3d printing anyway, so why do that? Maybe the chamfer helps reduce it, but it's not the best solution. And it sounds like the chamfer isn't ideal for preventing cross threading. My erratic correspondent seemed to think that threads made the "standard" way were worthless in 3d printed plastic if the parts were going to be disassembled and reassembled multiple times, though I admit that I don't understand why. He seemed to think---possibly based on experience with failed parts?--- that such threads just wouldn't last, and that the higbee end is essential. On Sun, Feb 19, 2023 at 5:39 PM nop head <nop.head@gmail.com> wrote: > I am not an expert but I think normal machine screws that you can buy the > thread at the end tapers in diameter, so it sort of follows a chamfer. My > thread library supports that and a simple chamfered end, which is what you > get when you cut a threaded rod and then chamfer the end. > > Higbee seems to be cutting off the crests of the leading treads, making > them flat topped. It seems to be a second pass on a CNC lathe that uses a > flat ended grooving tool to remove the sharp crests left by the threading > tool when it meets the chamfer. > > On Sun, 19 Feb 2023 at 22:11, Adrian Mariano <avm4@cornell.edu> wrote: > >> Is there anybody out there who is an expert in threading with a deep >> understanding of how thread ends should be formed? I'm trying to figure >> out how the higbee ends in BOSL2 should work, and I got some feedback from >> an erratic individual who writes once a month that I was doing it all >> wrong. And I think that he was at least partly correct, but without better >> communication, I'm having trouble nailing down how to fix the >> implementation. >> >> So I'm left with a variety of questions about this topic and haven't had >> much luck researching this on line. >> >> 1. What is the ideal way to terminate threads, given that in 3d modeling >> we aren't constrained by machining limitations. How abruptly should the >> thread end? Should it taper in width? In short, what exactly should >> BOSL2 do when producing threads? >> >> 2. What kind of thread ends should a threading library support more >> broadly? Is one type of end enough? It seems like thread ends for plastic >> bottles taper in a different way than the patented higbee. >> >> 3. What type of thread endings does the term "higbee" apply to? The >> original patent refers to "blunt ends" and the modern nomenclature seems to >> be to move away from "higbee" to "blunt start", but my erratic >> correspondent insisted that any thread end where the thread wasn't clipped >> off by the end of the bold was a "higbee" and that the term "higbee" was >> best. >> >> 4. How exactly does the higbee thread prevent cross threading. How does >> cross threading happen? I guess this relates back to #1. When I was >> thinking about it I got a feeling it had to do with a lack of a >> fractionally wide thread, which can more easily engage at a funny angle. >> That would suggest that a thread that tapers in width would be bad, since >> it could suffer the same problem. Am I right about that? >> >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
NH
nop head
Mon, Feb 20, 2023 7:12 AM

I mainly model threads I can buy or make myself, rather than 3D print. I
don't think machine screws are tapped rods. I think they are stamped out.
They don't have higbee ends. They have tapered ends and I find that also
works fine for large 3D printed threads like screw tops for jars.

[image: image.png]

I don't remember seeing anything with a higbee thread but instead of
tapering inwards it gets truncated inwards instead. Perhaps it cross
threads less because the lack of sharp crest stops it tappings its own
thread but it isn't how normal screws are made.

On Sun, 19 Feb 2023 at 23:07, Adrian Mariano avm4@cornell.edu wrote:

I think a normal thread is created by tapping the thread onto a rod or
into a hole.  Possibly a chamfer is applied afterwards.  I think this is
done for normal machine screws because it's cheap and fast, not because it
is good.  In the context of 3d printed parts, there is no reason not to
choose the best option, because we aren't paying a machinist.  Furthermore,
the knife-thin edge that arises when you carry threading out to the end of
a rod is probably not the best shape for 3d printing anyway, so why do
that?  Maybe the chamfer helps reduce it, but it's not the best solution.
And it sounds like the chamfer isn't ideal for preventing cross threading.
My erratic correspondent seemed to think that threads made the "standard"
way were worthless in 3d printed plastic if the parts were going to be
disassembled and reassembled multiple times, though I admit that I don't
understand why.  He seemed to think---possibly based on experience with
failed parts?--- that such threads just wouldn't last, and that the higbee
end is essential.

On Sun, Feb 19, 2023 at 5:39 PM nop head nop.head@gmail.com wrote:

I am not an expert but I think normal machine screws that you can buy the
thread at the end tapers in diameter, so it sort of follows a chamfer. My
thread library supports that and a simple chamfered end, which is what you
get when you cut a threaded rod and then chamfer the end.

Higbee seems to be cutting off the crests of the leading treads, making
them flat topped. It seems to be a second pass on a CNC lathe that uses a
flat ended grooving tool to remove the sharp crests left by the threading
tool when it meets the chamfer.

On Sun, 19 Feb 2023 at 22:11, Adrian Mariano avm4@cornell.edu wrote:

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?  I'm trying to figure
out how the higbee ends in BOSL2 should work, and I got some feedback from
an erratic individual who writes once a month that I was doing it all
wrong.  And I think that he was at least partly correct, but without better
communication, I'm having trouble nailing down how to fix the
implementation.

So I'm left with a variety of questions about this topic and haven't had
much luck researching this on line.

  1. What is the ideal way to terminate threads, given that in 3d
    modeling we aren't constrained by machining limitations.  How abruptly
    should the thread end?  Should it taper in width?  In short, what exactly
    should BOSL2 do when producing threads?

  2. What kind of thread ends should a threading library support more
    broadly?  Is one type of end enough?  It seems like thread ends for plastic
    bottles taper in a different way than the patented higbee.

  3. What type of thread endings does the term "higbee" apply to?  The
    original patent refers to "blunt ends" and the modern nomenclature seems to
    be to move away from "higbee" to "blunt start", but my erratic
    correspondent insisted that any thread end where the thread wasn't clipped
    off by the end of the bold was a "higbee" and that the term "higbee" was
    best.

  4. How exactly does the higbee thread prevent cross threading.  How
    does cross threading happen?  I guess this relates back to #1.  When I was
    thinking about it I got a feeling it had to do with a lack of a
    fractionally wide thread, which can more easily engage at a funny angle.
    That would suggest that a thread that tapers in width would be bad, since
    it could suffer the same problem.  Am I right about that?


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To unsubscribe send an email to discuss-leave@lists.openscad.org


OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org


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To unsubscribe send an email to discuss-leave@lists.openscad.org

I mainly model threads I can buy or make myself, rather than 3D print. I don't think machine screws are tapped rods. I think they are stamped out. They don't have higbee ends. They have tapered ends and I find that also works fine for large 3D printed threads like screw tops for jars. [image: image.png] I don't remember seeing anything with a higbee thread but instead of tapering inwards it gets truncated inwards instead. Perhaps it cross threads less because the lack of sharp crest stops it tappings its own thread but it isn't how normal screws are made. On Sun, 19 Feb 2023 at 23:07, Adrian Mariano <avm4@cornell.edu> wrote: > I think a normal thread is created by tapping the thread onto a rod or > into a hole. Possibly a chamfer is applied afterwards. I think this is > done for normal machine screws because it's cheap and fast, not because it > is good. In the context of 3d printed parts, there is no reason not to > choose the best option, because we aren't paying a machinist. Furthermore, > the knife-thin edge that arises when you carry threading out to the end of > a rod is probably not the best shape for 3d printing anyway, so why do > that? Maybe the chamfer helps reduce it, but it's not the best solution. > And it sounds like the chamfer isn't ideal for preventing cross threading. > My erratic correspondent seemed to think that threads made the "standard" > way were worthless in 3d printed plastic if the parts were going to be > disassembled and reassembled multiple times, though I admit that I don't > understand why. He seemed to think---possibly based on experience with > failed parts?--- that such threads just wouldn't last, and that the higbee > end is essential. > > On Sun, Feb 19, 2023 at 5:39 PM nop head <nop.head@gmail.com> wrote: > >> I am not an expert but I think normal machine screws that you can buy the >> thread at the end tapers in diameter, so it sort of follows a chamfer. My >> thread library supports that and a simple chamfered end, which is what you >> get when you cut a threaded rod and then chamfer the end. >> >> Higbee seems to be cutting off the crests of the leading treads, making >> them flat topped. It seems to be a second pass on a CNC lathe that uses a >> flat ended grooving tool to remove the sharp crests left by the threading >> tool when it meets the chamfer. >> >> On Sun, 19 Feb 2023 at 22:11, Adrian Mariano <avm4@cornell.edu> wrote: >> >>> Is there anybody out there who is an expert in threading with a deep >>> understanding of how thread ends should be formed? I'm trying to figure >>> out how the higbee ends in BOSL2 should work, and I got some feedback from >>> an erratic individual who writes once a month that I was doing it all >>> wrong. And I think that he was at least partly correct, but without better >>> communication, I'm having trouble nailing down how to fix the >>> implementation. >>> >>> So I'm left with a variety of questions about this topic and haven't had >>> much luck researching this on line. >>> >>> 1. What is the ideal way to terminate threads, given that in 3d >>> modeling we aren't constrained by machining limitations. How abruptly >>> should the thread end? Should it taper in width? In short, what exactly >>> should BOSL2 do when producing threads? >>> >>> 2. What kind of thread ends should a threading library support more >>> broadly? Is one type of end enough? It seems like thread ends for plastic >>> bottles taper in a different way than the patented higbee. >>> >>> 3. What type of thread endings does the term "higbee" apply to? The >>> original patent refers to "blunt ends" and the modern nomenclature seems to >>> be to move away from "higbee" to "blunt start", but my erratic >>> correspondent insisted that any thread end where the thread wasn't clipped >>> off by the end of the bold was a "higbee" and that the term "higbee" was >>> best. >>> >>> 4. How exactly does the higbee thread prevent cross threading. How >>> does cross threading happen? I guess this relates back to #1. When I was >>> thinking about it I got a feeling it had to do with a lack of a >>> fractionally wide thread, which can more easily engage at a funny angle. >>> That would suggest that a thread that tapers in width would be bad, since >>> it could suffer the same problem. Am I right about that? >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>> >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
AM
Adrian Mariano
Mon, Feb 20, 2023 11:37 AM

I looked for info on how screws are made and it sounds like the normal way
is indeed to press them between a pair of flat dies.  This process could
not make a higbee end.

https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf
https://www.accu.co.uk/p/105-how-is-a-machine-screw-made

Second link has a video of a factory.  I guess the chamfer on the end is
included in the die?

But still the question of optimal thread ends remains.  Look at a jar or
plastic bottle and you will see smooth tapering thread ends, not ends that
run off the end like the picture above.  For example, SP400 threads:

[image: image.png]

So this seems like a better model for how 3d printed threads should look
than die pressed threads in metal.  We are not constrained---we can make
the thread end in 3d printed models.  And it sounds like that's better
design, so that's what should be done.

On Mon, Feb 20, 2023 at 2:13 AM nop head nop.head@gmail.com wrote:

I mainly model threads I can buy or make myself, rather than 3D print. I
don't think machine screws are tapped rods. I think they are stamped out.
They don't have higbee ends. They have tapered ends and I find that also
works fine for large 3D printed threads like screw tops for jars.

[image: image.png]

I don't remember seeing anything with a higbee thread but instead of
tapering inwards it gets truncated inwards instead. Perhaps it cross
threads less because the lack of sharp crest stops it tappings its own
thread but it isn't how normal screws are made.

On Sun, 19 Feb 2023 at 23:07, Adrian Mariano avm4@cornell.edu wrote:

I think a normal thread is created by tapping the thread onto a rod or
into a hole.  Possibly a chamfer is applied afterwards.  I think this is
done for normal machine screws because it's cheap and fast, not because it
is good.  In the context of 3d printed parts, there is no reason not to
choose the best option, because we aren't paying a machinist.  Furthermore,
the knife-thin edge that arises when you carry threading out to the end of
a rod is probably not the best shape for 3d printing anyway, so why do
that?  Maybe the chamfer helps reduce it, but it's not the best solution.
And it sounds like the chamfer isn't ideal for preventing cross threading.
My erratic correspondent seemed to think that threads made the "standard"
way were worthless in 3d printed plastic if the parts were going to be
disassembled and reassembled multiple times, though I admit that I don't
understand why.  He seemed to think---possibly based on experience with
failed parts?--- that such threads just wouldn't last, and that the higbee
end is essential.

On Sun, Feb 19, 2023 at 5:39 PM nop head nop.head@gmail.com wrote:

I am not an expert but I think normal machine screws that you can buy
the thread at the end tapers in diameter, so it sort of follows a chamfer.
My thread library supports that and a simple chamfered end, which is what
you get when you cut a threaded rod and then chamfer the end.

Higbee seems to be cutting off the crests of the leading treads, making
them flat topped. It seems to be a second pass on a CNC lathe that uses a
flat ended grooving tool to remove the sharp crests left by the threading
tool when it meets the chamfer.

On Sun, 19 Feb 2023 at 22:11, Adrian Mariano avm4@cornell.edu wrote:

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?  I'm trying to figure
out how the higbee ends in BOSL2 should work, and I got some feedback from
an erratic individual who writes once a month that I was doing it all
wrong.  And I think that he was at least partly correct, but without better
communication, I'm having trouble nailing down how to fix the
implementation.

So I'm left with a variety of questions about this topic and haven't
had much luck researching this on line.

  1. What is the ideal way to terminate threads, given that in 3d
    modeling we aren't constrained by machining limitations.  How abruptly
    should the thread end?  Should it taper in width?  In short, what exactly
    should BOSL2 do when producing threads?

  2. What kind of thread ends should a threading library support more
    broadly?  Is one type of end enough?  It seems like thread ends for plastic
    bottles taper in a different way than the patented higbee.

  3. What type of thread endings does the term "higbee" apply to?  The
    original patent refers to "blunt ends" and the modern nomenclature seems to
    be to move away from "higbee" to "blunt start", but my erratic
    correspondent insisted that any thread end where the thread wasn't clipped
    off by the end of the bold was a "higbee" and that the term "higbee" was
    best.

  4. How exactly does the higbee thread prevent cross threading.  How
    does cross threading happen?  I guess this relates back to #1.  When I was
    thinking about it I got a feeling it had to do with a lack of a
    fractionally wide thread, which can more easily engage at a funny angle.
    That would suggest that a thread that tapers in width would be bad, since
    it could suffer the same problem.  Am I right about that?


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To unsubscribe send an email to discuss-leave@lists.openscad.org


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To unsubscribe send an email to discuss-leave@lists.openscad.org


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I looked for info on how screws are made and it sounds like the normal way is indeed to press them between a pair of flat dies. This process could not make a higbee end. https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf https://www.accu.co.uk/p/105-how-is-a-machine-screw-made Second link has a video of a factory. I guess the chamfer on the end is included in the die? But still the question of optimal thread ends remains. Look at a jar or plastic bottle and you will see smooth tapering thread ends, not ends that run off the end like the picture above. For example, SP400 threads: [image: image.png] So this seems like a better model for how 3d printed threads should look than die pressed threads in metal. We are not constrained---we can make the thread end in 3d printed models. And it sounds like that's better design, so that's what should be done. On Mon, Feb 20, 2023 at 2:13 AM nop head <nop.head@gmail.com> wrote: > I mainly model threads I can buy or make myself, rather than 3D print. I > don't think machine screws are tapped rods. I think they are stamped out. > They don't have higbee ends. They have tapered ends and I find that also > works fine for large 3D printed threads like screw tops for jars. > > [image: image.png] > > I don't remember seeing anything with a higbee thread but instead of > tapering inwards it gets truncated inwards instead. Perhaps it cross > threads less because the lack of sharp crest stops it tappings its own > thread but it isn't how normal screws are made. > > On Sun, 19 Feb 2023 at 23:07, Adrian Mariano <avm4@cornell.edu> wrote: > >> I think a normal thread is created by tapping the thread onto a rod or >> into a hole. Possibly a chamfer is applied afterwards. I think this is >> done for normal machine screws because it's cheap and fast, not because it >> is good. In the context of 3d printed parts, there is no reason not to >> choose the best option, because we aren't paying a machinist. Furthermore, >> the knife-thin edge that arises when you carry threading out to the end of >> a rod is probably not the best shape for 3d printing anyway, so why do >> that? Maybe the chamfer helps reduce it, but it's not the best solution. >> And it sounds like the chamfer isn't ideal for preventing cross threading. >> My erratic correspondent seemed to think that threads made the "standard" >> way were worthless in 3d printed plastic if the parts were going to be >> disassembled and reassembled multiple times, though I admit that I don't >> understand why. He seemed to think---possibly based on experience with >> failed parts?--- that such threads just wouldn't last, and that the higbee >> end is essential. >> >> On Sun, Feb 19, 2023 at 5:39 PM nop head <nop.head@gmail.com> wrote: >> >>> I am not an expert but I think normal machine screws that you can buy >>> the thread at the end tapers in diameter, so it sort of follows a chamfer. >>> My thread library supports that and a simple chamfered end, which is what >>> you get when you cut a threaded rod and then chamfer the end. >>> >>> Higbee seems to be cutting off the crests of the leading treads, making >>> them flat topped. It seems to be a second pass on a CNC lathe that uses a >>> flat ended grooving tool to remove the sharp crests left by the threading >>> tool when it meets the chamfer. >>> >>> On Sun, 19 Feb 2023 at 22:11, Adrian Mariano <avm4@cornell.edu> wrote: >>> >>>> Is there anybody out there who is an expert in threading with a deep >>>> understanding of how thread ends should be formed? I'm trying to figure >>>> out how the higbee ends in BOSL2 should work, and I got some feedback from >>>> an erratic individual who writes once a month that I was doing it all >>>> wrong. And I think that he was at least partly correct, but without better >>>> communication, I'm having trouble nailing down how to fix the >>>> implementation. >>>> >>>> So I'm left with a variety of questions about this topic and haven't >>>> had much luck researching this on line. >>>> >>>> 1. What is the ideal way to terminate threads, given that in 3d >>>> modeling we aren't constrained by machining limitations. How abruptly >>>> should the thread end? Should it taper in width? In short, what exactly >>>> should BOSL2 do when producing threads? >>>> >>>> 2. What kind of thread ends should a threading library support more >>>> broadly? Is one type of end enough? It seems like thread ends for plastic >>>> bottles taper in a different way than the patented higbee. >>>> >>>> 3. What type of thread endings does the term "higbee" apply to? The >>>> original patent refers to "blunt ends" and the modern nomenclature seems to >>>> be to move away from "higbee" to "blunt start", but my erratic >>>> correspondent insisted that any thread end where the thread wasn't clipped >>>> off by the end of the bold was a "higbee" and that the term "higbee" was >>>> best. >>>> >>>> 4. How exactly does the higbee thread prevent cross threading. How >>>> does cross threading happen? I guess this relates back to #1. When I was >>>> thinking about it I got a feeling it had to do with a lack of a >>>> fractionally wide thread, which can more easily engage at a funny angle. >>>> That would suggest that a thread that tapers in width would be bad, since >>>> it could suffer the same problem. Am I right about that? >>>> >>>> _______________________________________________ >>>> OpenSCAD mailing list >>>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>> >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
NH
nop head
Mon, Feb 20, 2023 1:54 PM

That bottle thread is just tapered off much faster and then doesn't go
right to the end of the tube. I think my library does it over half a turn.
Here is a drill case I printed and it never cross threads.

[image: image.png]
It is different with fine thread in metal though as it is much easier to
cross thread if say you put a steel screw into brass.

On Mon, 20 Feb 2023 at 11:38, Adrian Mariano avm4@cornell.edu wrote:

I looked for info on how screws are made and it sounds like the normal way
is indeed to press them between a pair of flat dies.  This process could
not make a higbee end.

https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf
https://www.accu.co.uk/p/105-how-is-a-machine-screw-made

Second link has a video of a factory.  I guess the chamfer on the end is
included in the die?

But still the question of optimal thread ends remains.  Look at a jar or
plastic bottle and you will see smooth tapering thread ends, not ends that
run off the end like the picture above.  For example, SP400 threads:

[image: image.png]

So this seems like a better model for how 3d printed threads should look
than die pressed threads in metal.  We are not constrained---we can make
the thread end in 3d printed models.  And it sounds like that's better
design, so that's what should be done.

On Mon, Feb 20, 2023 at 2:13 AM nop head nop.head@gmail.com wrote:

I mainly model threads I can buy or make myself, rather than 3D print. I
don't think machine screws are tapped rods. I think they are stamped out.
They don't have higbee ends. They have tapered ends and I find that also
works fine for large 3D printed threads like screw tops for jars.

[image: image.png]

I don't remember seeing anything with a higbee thread but instead of
tapering inwards it gets truncated inwards instead. Perhaps it cross
threads less because the lack of sharp crest stops it tappings its own
thread but it isn't how normal screws are made.

On Sun, 19 Feb 2023 at 23:07, Adrian Mariano avm4@cornell.edu wrote:

I think a normal thread is created by tapping the thread onto a rod or
into a hole.  Possibly a chamfer is applied afterwards.  I think this is
done for normal machine screws because it's cheap and fast, not because it
is good.  In the context of 3d printed parts, there is no reason not to
choose the best option, because we aren't paying a machinist.  Furthermore,
the knife-thin edge that arises when you carry threading out to the end of
a rod is probably not the best shape for 3d printing anyway, so why do
that?  Maybe the chamfer helps reduce it, but it's not the best solution.
And it sounds like the chamfer isn't ideal for preventing cross threading.
My erratic correspondent seemed to think that threads made the "standard"
way were worthless in 3d printed plastic if the parts were going to be
disassembled and reassembled multiple times, though I admit that I don't
understand why.  He seemed to think---possibly based on experience with
failed parts?--- that such threads just wouldn't last, and that the higbee
end is essential.

On Sun, Feb 19, 2023 at 5:39 PM nop head nop.head@gmail.com wrote:

I am not an expert but I think normal machine screws that you can buy
the thread at the end tapers in diameter, so it sort of follows a chamfer.
My thread library supports that and a simple chamfered end, which is what
you get when you cut a threaded rod and then chamfer the end.

Higbee seems to be cutting off the crests of the leading treads, making
them flat topped. It seems to be a second pass on a CNC lathe that uses a
flat ended grooving tool to remove the sharp crests left by the threading
tool when it meets the chamfer.

On Sun, 19 Feb 2023 at 22:11, Adrian Mariano avm4@cornell.edu wrote:

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?  I'm trying to figure
out how the higbee ends in BOSL2 should work, and I got some feedback from
an erratic individual who writes once a month that I was doing it all
wrong.  And I think that he was at least partly correct, but without better
communication, I'm having trouble nailing down how to fix the
implementation.

So I'm left with a variety of questions about this topic and haven't
had much luck researching this on line.

  1. What is the ideal way to terminate threads, given that in 3d
    modeling we aren't constrained by machining limitations.  How abruptly
    should the thread end?  Should it taper in width?  In short, what exactly
    should BOSL2 do when producing threads?

  2. What kind of thread ends should a threading library support more
    broadly?  Is one type of end enough?  It seems like thread ends for plastic
    bottles taper in a different way than the patented higbee.

  3. What type of thread endings does the term "higbee" apply to?  The
    original patent refers to "blunt ends" and the modern nomenclature seems to
    be to move away from "higbee" to "blunt start", but my erratic
    correspondent insisted that any thread end where the thread wasn't clipped
    off by the end of the bold was a "higbee" and that the term "higbee" was
    best.

  4. How exactly does the higbee thread prevent cross threading.  How
    does cross threading happen?  I guess this relates back to #1.  When I was
    thinking about it I got a feeling it had to do with a lack of a
    fractionally wide thread, which can more easily engage at a funny angle.
    That would suggest that a thread that tapers in width would be bad, since
    it could suffer the same problem.  Am I right about that?


OpenSCAD mailing list
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To unsubscribe send an email to discuss-leave@lists.openscad.org


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To unsubscribe send an email to discuss-leave@lists.openscad.org


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That bottle thread is just tapered off much faster and then doesn't go right to the end of the tube. I think my library does it over half a turn. Here is a drill case I printed and it never cross threads. [image: image.png] It is different with fine thread in metal though as it is much easier to cross thread if say you put a steel screw into brass. On Mon, 20 Feb 2023 at 11:38, Adrian Mariano <avm4@cornell.edu> wrote: > I looked for info on how screws are made and it sounds like the normal way > is indeed to press them between a pair of flat dies. This process could > not make a higbee end. > > > https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf > https://www.accu.co.uk/p/105-how-is-a-machine-screw-made > > Second link has a video of a factory. I guess the chamfer on the end is > included in the die? > > But still the question of optimal thread ends remains. Look at a jar or > plastic bottle and you will see smooth tapering thread ends, not ends that > run off the end like the picture above. For example, SP400 threads: > > [image: image.png] > > So this seems like a better model for how 3d printed threads should look > than die pressed threads in metal. We are not constrained---we can make > the thread end in 3d printed models. And it sounds like that's better > design, so that's what should be done. > > > On Mon, Feb 20, 2023 at 2:13 AM nop head <nop.head@gmail.com> wrote: > >> I mainly model threads I can buy or make myself, rather than 3D print. I >> don't think machine screws are tapped rods. I think they are stamped out. >> They don't have higbee ends. They have tapered ends and I find that also >> works fine for large 3D printed threads like screw tops for jars. >> >> [image: image.png] >> >> I don't remember seeing anything with a higbee thread but instead of >> tapering inwards it gets truncated inwards instead. Perhaps it cross >> threads less because the lack of sharp crest stops it tappings its own >> thread but it isn't how normal screws are made. >> >> On Sun, 19 Feb 2023 at 23:07, Adrian Mariano <avm4@cornell.edu> wrote: >> >>> I think a normal thread is created by tapping the thread onto a rod or >>> into a hole. Possibly a chamfer is applied afterwards. I think this is >>> done for normal machine screws because it's cheap and fast, not because it >>> is good. In the context of 3d printed parts, there is no reason not to >>> choose the best option, because we aren't paying a machinist. Furthermore, >>> the knife-thin edge that arises when you carry threading out to the end of >>> a rod is probably not the best shape for 3d printing anyway, so why do >>> that? Maybe the chamfer helps reduce it, but it's not the best solution. >>> And it sounds like the chamfer isn't ideal for preventing cross threading. >>> My erratic correspondent seemed to think that threads made the "standard" >>> way were worthless in 3d printed plastic if the parts were going to be >>> disassembled and reassembled multiple times, though I admit that I don't >>> understand why. He seemed to think---possibly based on experience with >>> failed parts?--- that such threads just wouldn't last, and that the higbee >>> end is essential. >>> >>> On Sun, Feb 19, 2023 at 5:39 PM nop head <nop.head@gmail.com> wrote: >>> >>>> I am not an expert but I think normal machine screws that you can buy >>>> the thread at the end tapers in diameter, so it sort of follows a chamfer. >>>> My thread library supports that and a simple chamfered end, which is what >>>> you get when you cut a threaded rod and then chamfer the end. >>>> >>>> Higbee seems to be cutting off the crests of the leading treads, making >>>> them flat topped. It seems to be a second pass on a CNC lathe that uses a >>>> flat ended grooving tool to remove the sharp crests left by the threading >>>> tool when it meets the chamfer. >>>> >>>> On Sun, 19 Feb 2023 at 22:11, Adrian Mariano <avm4@cornell.edu> wrote: >>>> >>>>> Is there anybody out there who is an expert in threading with a deep >>>>> understanding of how thread ends should be formed? I'm trying to figure >>>>> out how the higbee ends in BOSL2 should work, and I got some feedback from >>>>> an erratic individual who writes once a month that I was doing it all >>>>> wrong. And I think that he was at least partly correct, but without better >>>>> communication, I'm having trouble nailing down how to fix the >>>>> implementation. >>>>> >>>>> So I'm left with a variety of questions about this topic and haven't >>>>> had much luck researching this on line. >>>>> >>>>> 1. What is the ideal way to terminate threads, given that in 3d >>>>> modeling we aren't constrained by machining limitations. How abruptly >>>>> should the thread end? Should it taper in width? In short, what exactly >>>>> should BOSL2 do when producing threads? >>>>> >>>>> 2. What kind of thread ends should a threading library support more >>>>> broadly? Is one type of end enough? It seems like thread ends for plastic >>>>> bottles taper in a different way than the patented higbee. >>>>> >>>>> 3. What type of thread endings does the term "higbee" apply to? The >>>>> original patent refers to "blunt ends" and the modern nomenclature seems to >>>>> be to move away from "higbee" to "blunt start", but my erratic >>>>> correspondent insisted that any thread end where the thread wasn't clipped >>>>> off by the end of the bold was a "higbee" and that the term "higbee" was >>>>> best. >>>>> >>>>> 4. How exactly does the higbee thread prevent cross threading. How >>>>> does cross threading happen? I guess this relates back to #1. When I was >>>>> thinking about it I got a feeling it had to do with a lack of a >>>>> fractionally wide thread, which can more easily engage at a funny angle. >>>>> That would suggest that a thread that tapers in width would be bad, since >>>>> it could suffer the same problem. Am I right about that? >>>>> >>>>> _______________________________________________ >>>>> OpenSCAD mailing list >>>>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>>>> >>>> _______________________________________________ >>>> OpenSCAD mailing list >>>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> To unsubscribe send an email to discuss-leave@lists.openscad.org >>> >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
GH
gene heskett
Mon, Feb 20, 2023 2:29 PM

On 2/20/23 06:39, Adrian Mariano wrote:

I looked for info on how screws are made and it sounds like the normal
way is indeed to press them between a pair of flat dies.  This process
could not make a higbee end.

https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf
https://www.accu.co.uk/p/105-how-is-a-machine-screw-made
https://www.accu.co.uk/p/105-how-is-a-machine-screw-made

Second link has a video of a factory.  I guess the chamfer on the end is
included in the die?

But still the question of optimal thread ends remains.  Look at a jar or
plastic bottle and you will see smooth tapering thread ends, not ends
that run off the end like the picture above.  For example, SP400 threads:

image.png

So this seems like a better model for how 3d printed threads should look
than die pressed threads in metal.  We are not constrained---we can make
the thread end in 3d printed models.  And it sounds like that's better
design, so that's what should be done.

On Mon, Feb 20, 2023 at 2:13 AM nop head <nop.head@gmail.com
mailto:nop.head@gmail.com> wrote:

 I mainly model threads I can buy or make myself, rather than 3D
 print. I don't think machine screws are tapped rods. I think they
 are stamped out. They don't have higbee ends. They have tapered ends
 and I find that also works fine for large 3D printed threads like
 screw tops for jars.

 image.png

 I don't remember seeing anything with a higbee thread but instead of
 tapering inwards it gets truncated inwards instead. Perhaps it cross
 threads less because the lack of sharp crest stops it tappings its
 own thread but it isn't how normal screws are made.

 On Sun, 19 Feb 2023 at 23:07, Adrian Mariano <avm4@cornell.edu
 <mailto:avm4@cornell.edu>> wrote:

     I think a normal thread is created by tapping the thread onto a
     rod or into a hole.  Possibly a chamfer is applied afterwards. 
     I think this is done for normal machine screws because it's
     cheap and fast, not because it is good.  In the context of 3d
     printed parts, there is no reason not to choose the best option,
     because we aren't paying a machinist.  Furthermore, the
     knife-thin edge that arises when you carry threading out to the
     end of a rod is probably not the best shape for 3d printing
     anyway, so why do that?  Maybe the chamfer helps reduce it, but
     it's not the best solution.   And it sounds like the chamfer
     isn't ideal for preventing cross threading.  My erratic
     correspondent seemed to think that threads made the "standard"
     way were worthless in 3d printed plastic if the parts were going
     to be disassembled and reassembled multiple times, though I
     admit that I don't understand why.  He seemed to
     think---possibly based on experience with failed parts?--- that
     such threads just wouldn't last, and that the higbee end is
     essential.

     On Sun, Feb 19, 2023 at 5:39 PM nop head <nop.head@gmail.com
     <mailto:nop.head@gmail.com>> wrote:

         I am not an expert but I think normal machine screws that
         you can buy the thread at the end tapers in diameter, so it
         sort of follows a chamfer. My thread library supports that
         and a simple chamfered end, which is what you get when you
         cut a threaded rod and then chamfer the end.

         Higbee seems to be cutting off the crests of the leading
         treads, making them flat topped. It seems to be a second
         pass on a CNC lathe that uses a flat ended grooving tool to
         remove the sharp crests left by the threading tool when it
         meets the chamfer.

         On Sun, 19 Feb 2023 at 22:11, Adrian Mariano
         <avm4@cornell.edu <mailto:avm4@cornell.edu>> wrote:

             Is there anybody out there who is an expert in threading
             with a deep understanding of how thread ends should be
             formed?   I'm trying to figure out how the higbee ends
             in BOSL2 should work, and I got some feedback from an
             erratic individual who writes once a month that I was
             doing it all wrong.  And I think that he was at least
             partly correct, but without better communication, I'm
             having trouble nailing down how to fix the implementation.

             So I'm left with a variety of questions about this topic
             and haven't had much luck researching this on line.

             1.  What is the ideal way to terminate threads, given
             that in 3d modeling we aren't constrained by machining
             limitations.   How abruptly should the thread end? 
             Should it taper in width?   In short, what exactly
             should BOSL2 do when producing threads?

             2. What kind of thread ends should a threading library
             support more broadly?  Is one type of end enough?  It
             seems like thread ends for plastic bottles taper in a
             different way than the patented higbee.

             3.  What type of thread endings does the term "higbee"
             apply to?  The original patent refers to "blunt ends"
             and the modern nomenclature seems to be to move away
             from "higbee" to "blunt start", but my erratic
             correspondent insisted that any thread end where the
             thread wasn't clipped off by the end of the bold was a
             "higbee" and that the term "higbee" was best.

             4.  How exactly does the higbee thread prevent cross
             threading.  How does cross threading happen?  I guess
             this relates back to #1.  When I was thinking about it I
             got a feeling it had to do with a lack of a fractionally
             wide thread, which can more easily engage at a funny
             angle.  That would suggest that a thread that tapers in
             width would be bad, since it could suffer the same
             problem.  Am I right about that?

The only comment I can make is not expert, I'm not a pro machinist, just
a retired broadcast engineer. But I have used it many times, I have 4
cnc'ed machines I rebuilt from manual stuff and converted to cnc.

The ability to control the entry and withdraw profiles that LinuxCNC's
G76 canned threading can do, normally used where threading the middle of
a rod to make a bolt or nut, where the single tooth cutter is ramped
from its baseline to the depth of the thread being cut on this pass,
internal thread or external being auto selected by the base line being
inside or or outside of the thread G76 has a length for that, normally
used to give a fraction of a turn profile for the ends of the thread.

Normally used for the entry, aka the right hand end of the thread, the
other end, visualize that as at the underside of a bolts head, is either
subject to a precut groove to give the tool room to withdraw at an
achievable speed. Or you can just let the withdraw ramp out to a bolt
shank diameter withdraw as long as the tool doesn't actually touch the
underside of the head.

But this old Iowa farm kid thinks outside of the box now and then, and
needing a compression method of attaching the drive from the motor,
where an un-machined end of a ball screw is inserted to a slotted sleeve
that is intended to be compressed to grip the screw as effectively as a
weld w/o the distortions you get from the welding heat. The slots, cut
to the depth of the socket drilled, are done with EDM because its very
precise and leaves no burrs to interfere with the fit. So I found I
could make a tapered thread, length of taper cut being one turn less
than the length of the thread, doing the thread ahead of the EDM
slotting, and I made nuts out of stock 3/8" nuts to fit it, both at 50
tpi. On a 7x12 cnc'ed lathe.

It got me the grip I needed, precisely on center with no runout And
never a hint of wanting to cross-thread because the working space was
way to small to get any fingers in to guide it. That was a decade + back
up the log and has not been touched since. So I'll make the claim that a
long enough straight taper cannot be cross threaded. Its self
correcting. I'd assume that characteristic would survive down to a taper
done as a single turn. 1/4 turn ramps I'm less certain of.

This is control you don't get using taps and dies. And its a single data
point from multiple such uses experience. YMMV.

Take care & stay well, all.

Cheers, Gene Heskett.

"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.

On 2/20/23 06:39, Adrian Mariano wrote: > I looked for info on how screws are made and it sounds like the normal > way is indeed to press them between a pair of flat dies.  This process > could not make a higbee end. > > https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf <https://www.wuerth-industrie.com/web/media/en/pictures/wuerthindustrie/technikportal/dinokapitel/Kapitel_04_DINO_techn_Teil.pdf> > https://www.accu.co.uk/p/105-how-is-a-machine-screw-made > <https://www.accu.co.uk/p/105-how-is-a-machine-screw-made> > > Second link has a video of a factory.  I guess the chamfer on the end is > included in the die? > > But still the question of optimal thread ends remains.  Look at a jar or > plastic bottle and you will see smooth tapering thread ends, not ends > that run off the end like the picture above.  For example, SP400 threads: > > image.png > > So this seems like a better model for how 3d printed threads should look > than die pressed threads in metal.  We are not constrained---we can make > the thread end in 3d printed models.  And it sounds like that's better > design, so that's what should be done. > > > On Mon, Feb 20, 2023 at 2:13 AM nop head <nop.head@gmail.com > <mailto:nop.head@gmail.com>> wrote: > > I mainly model threads I can buy or make myself, rather than 3D > print. I don't think machine screws are tapped rods. I think they > are stamped out. They don't have higbee ends. They have tapered ends > and I find that also works fine for large 3D printed threads like > screw tops for jars. > > image.png > > I don't remember seeing anything with a higbee thread but instead of > tapering inwards it gets truncated inwards instead. Perhaps it cross > threads less because the lack of sharp crest stops it tappings its > own thread but it isn't how normal screws are made. > > On Sun, 19 Feb 2023 at 23:07, Adrian Mariano <avm4@cornell.edu > <mailto:avm4@cornell.edu>> wrote: > > I think a normal thread is created by tapping the thread onto a > rod or into a hole.  Possibly a chamfer is applied afterwards. > I think this is done for normal machine screws because it's > cheap and fast, not because it is good.  In the context of 3d > printed parts, there is no reason not to choose the best option, > because we aren't paying a machinist.  Furthermore, the > knife-thin edge that arises when you carry threading out to the > end of a rod is probably not the best shape for 3d printing > anyway, so why do that?  Maybe the chamfer helps reduce it, but > it's not the best solution.   And it sounds like the chamfer > isn't ideal for preventing cross threading.  My erratic > correspondent seemed to think that threads made the "standard" > way were worthless in 3d printed plastic if the parts were going > to be disassembled and reassembled multiple times, though I > admit that I don't understand why.  He seemed to > think---possibly based on experience with failed parts?--- that > such threads just wouldn't last, and that the higbee end is > essential. > > On Sun, Feb 19, 2023 at 5:39 PM nop head <nop.head@gmail.com > <mailto:nop.head@gmail.com>> wrote: > > I am not an expert but I think normal machine screws that > you can buy the thread at the end tapers in diameter, so it > sort of follows a chamfer. My thread library supports that > and a simple chamfered end, which is what you get when you > cut a threaded rod and then chamfer the end. > > Higbee seems to be cutting off the crests of the leading > treads, making them flat topped. It seems to be a second > pass on a CNC lathe that uses a flat ended grooving tool to > remove the sharp crests left by the threading tool when it > meets the chamfer. > > On Sun, 19 Feb 2023 at 22:11, Adrian Mariano > <avm4@cornell.edu <mailto:avm4@cornell.edu>> wrote: > > Is there anybody out there who is an expert in threading > with a deep understanding of how thread ends should be > formed?   I'm trying to figure out how the higbee ends > in BOSL2 should work, and I got some feedback from an > erratic individual who writes once a month that I was > doing it all wrong.  And I think that he was at least > partly correct, but without better communication, I'm > having trouble nailing down how to fix the implementation. > > So I'm left with a variety of questions about this topic > and haven't had much luck researching this on line. > > 1.  What is the ideal way to terminate threads, given > that in 3d modeling we aren't constrained by machining > limitations.   How abruptly should the thread end? > Should it taper in width?   In short, what exactly > should BOSL2 do when producing threads? > > 2. What kind of thread ends should a threading library > support more broadly?  Is one type of end enough?  It > seems like thread ends for plastic bottles taper in a > different way than the patented higbee. > > 3.  What type of thread endings does the term "higbee" > apply to?  The original patent refers to "blunt ends" > and the modern nomenclature seems to be to move away > from "higbee" to "blunt start", but my erratic > correspondent insisted that any thread end where the > thread wasn't clipped off by the end of the bold was a > "higbee" and that the term "higbee" was best. > > 4.  How exactly does the higbee thread prevent cross > threading.  How does cross threading happen?  I guess > this relates back to #1.  When I was thinking about it I > got a feeling it had to do with a lack of a fractionally > wide thread, which can more easily engage at a funny > angle.  That would suggest that a thread that tapers in > width would be bad, since it could suffer the same > problem.  Am I right about that? The only comment I can make is not expert, I'm not a pro machinist, just a retired broadcast engineer. But I have used it many times, I have 4 cnc'ed machines I rebuilt from manual stuff and converted to cnc. The ability to control the entry and withdraw profiles that LinuxCNC's G76 canned threading can do, normally used where threading the middle of a rod to make a bolt or nut, where the single tooth cutter is ramped from its baseline to the depth of the thread being cut on this pass, internal thread or external being auto selected by the base line being inside or or outside of the thread G76 has a length for that, normally used to give a fraction of a turn profile for the ends of the thread. Normally used for the entry, aka the right hand end of the thread, the other end, visualize that as at the underside of a bolts head, is either subject to a precut groove to give the tool room to withdraw at an achievable speed. Or you can just let the withdraw ramp out to a bolt shank diameter withdraw as long as the tool doesn't actually touch the underside of the head. But this old Iowa farm kid thinks outside of the box now and then, and needing a compression method of attaching the drive from the motor, where an un-machined end of a ball screw is inserted to a slotted sleeve that is intended to be compressed to grip the screw as effectively as a weld w/o the distortions you get from the welding heat. The slots, cut to the depth of the socket drilled, are done with EDM because its very precise and leaves no burrs to interfere with the fit. So I found I could make a tapered thread, length of taper cut being one turn less than the length of the thread, doing the thread ahead of the EDM slotting, and I made nuts out of stock 3/8" nuts to fit it, both at 50 tpi. On a 7x12 cnc'ed lathe. It got me the grip I needed, precisely on center with no runout And never a hint of wanting to cross-thread because the working space was way to small to get any fingers in to guide it. That was a decade + back up the log and has not been touched since. So I'll make the claim that a long enough straight taper cannot be cross threaded. Its self correcting. I'd assume that characteristic would survive down to a taper done as a single turn. 1/4 turn ramps I'm less certain of. This is control you don't get using taps and dies. And its a single data point from multiple such uses experience. YMMV. Take care & stay well, all. Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/>
RW
Rogier Wolff
Mon, Feb 20, 2023 2:44 PM

On Mon, Feb 20, 2023 at 06:37:37AM -0500, Adrian Mariano wrote:

I looked for info on how screws are made and it sounds like the
normal way is indeed to press them between a pair of flat dies.
This process could not make a higbee end.

I checked out your link, because I didn't think the shape of a screw
could be pressed between two dies.

Turns out the ROLL the pre-screw between the two dies. In hindsight
The hint was there with the /flat/ dies, but for sure they cannot be
FLAT because that'd make them "cylindrical" instead of a screw.

(If I'm honest... I'd make the dies round (on the outside of a big
wheel (*)) so that you can rotate them. rotate them in opposite
directions so that the screws remain stationary.  Then turn one
slightly faster so that after enough rotations it drops down between
the two big dies after enough of an impression has been made. Feed a
new pre-screw in due time. I'd think one machine can then thread 36000
screws per hour easily.)

Roger. 

(*) You can calculate the size of the required wheel by knowing
howmany rotations of the screw you want between the dies (i.e. length
of the trajectory from original cylinder to "finished screw" )

--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 **
**    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233    **
f equals m times a. When your f is steady, and your m is going down
your a is going up.  -- Chris Hadfield about flying up the space shuttle.

On Mon, Feb 20, 2023 at 06:37:37AM -0500, Adrian Mariano wrote: > I looked for info on how screws are made and it sounds like the > normal way is indeed to press them between a pair of flat dies. > This process could not make a higbee end. I checked out your link, because I didn't think the shape of a screw could be pressed between two dies. Turns out the ROLL the pre-screw between the two dies. In hindsight The hint was there with the /flat/ dies, but for sure they cannot be FLAT because that'd make them "cylindrical" instead of a screw. (If I'm honest... I'd make the dies round (on the outside of a big wheel (*)) so that you can rotate them. rotate them in opposite directions so that the screws remain stationary. Then turn one slightly faster so that after enough rotations it drops down between the two big dies after enough of an impression has been made. Feed a new pre-screw in due time. I'd think one machine can then thread 36000 screws per hour easily.) Roger. (*) You can calculate the size of the required wheel by knowing howmany rotations of the screw you want between the dies (i.e. length of the trajectory from original cylinder to "finished screw" ) -- ** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 ** ** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 ** f equals m times a. When your f is steady, and your m is going down your a is going up. -- Chris Hadfield about flying up the space shuttle.
NH
nop head
Mon, Feb 20, 2023 2:55 PM

Thinking some more about it, I think higbee only makes sense when you have
a thread already made and you want to clean up the end. The optimal end
shape is simply tapered when you can mould it or 3D print it.

On Mon, 20 Feb 2023 at 14:45, Rogier Wolff R.E.Wolff@bitwizard.nl wrote:

On Mon, Feb 20, 2023 at 06:37:37AM -0500, Adrian Mariano wrote:

I looked for info on how screws are made and it sounds like the
normal way is indeed to press them between a pair of flat dies.
This process could not make a higbee end.

I checked out your link, because I didn't think the shape of a screw
could be pressed between two dies.

Turns out the ROLL the pre-screw between the two dies. In hindsight
The hint was there with the /flat/ dies, but for sure they cannot be
FLAT because that'd make them "cylindrical" instead of a screw.

(If I'm honest... I'd make the dies round (on the outside of a big
wheel (*)) so that you can rotate them. rotate them in opposite
directions so that the screws remain stationary.  Then turn one
slightly faster so that after enough rotations it drops down between
the two big dies after enough of an impression has been made. Feed a
new pre-screw in due time. I'd think one machine can then thread 36000
screws per hour easily.)

     Roger.

(*) You can calculate the size of the required wheel by knowing
howmany rotations of the screw you want between the dies (i.e. length
of the trajectory from original cylinder to "finished screw" )

--
** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110
**
**    Delftechpark 11 2628 XJ  Delft, The Netherlands.  KVK: 27239233    **
f equals m times a. When your f is steady, and your m is going down
your a is going up.  -- Chris Hadfield about flying up the space shuttle.


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Thinking some more about it, I think higbee only makes sense when you have a thread already made and you want to clean up the end. The optimal end shape is simply tapered when you can mould it or 3D print it. On Mon, 20 Feb 2023 at 14:45, Rogier Wolff <R.E.Wolff@bitwizard.nl> wrote: > On Mon, Feb 20, 2023 at 06:37:37AM -0500, Adrian Mariano wrote: > > I looked for info on how screws are made and it sounds like the > > normal way is indeed to press them between a pair of flat dies. > > This process could not make a higbee end. > > I checked out your link, because I didn't think the shape of a screw > could be pressed between two dies. > > Turns out the ROLL the pre-screw between the two dies. In hindsight > The hint was there with the /flat/ dies, but for sure they cannot be > FLAT because that'd make them "cylindrical" instead of a screw. > > (If I'm honest... I'd make the dies round (on the outside of a big > wheel (*)) so that you can rotate them. rotate them in opposite > directions so that the screws remain stationary. Then turn one > slightly faster so that after enough rotations it drops down between > the two big dies after enough of an impression has been made. Feed a > new pre-screw in due time. I'd think one machine can then thread 36000 > screws per hour easily.) > > Roger. > > (*) You can calculate the size of the required wheel by knowing > howmany rotations of the screw you want between the dies (i.e. length > of the trajectory from original cylinder to "finished screw" ) > > -- > ** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 > ** > ** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 ** > f equals m times a. When your f is steady, and your m is going down > your a is going up. -- Chris Hadfield about flying up the space shuttle. > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >
RW
Raymond West
Mon, Feb 20, 2023 4:48 PM

On 19/02/2023 22:09, Adrian Mariano wrote:

Is there anybody out there who is an expert in threading with a deep
understanding of how thread ends should be formed?

It depends somewhat on the the way the bolt or stud is manufactured, and
its final application. For example, the screws that hold a switch plate
to the wall box, will have a short length at core diameter, so that it
can 'find' the tapped hole in said box, and allow the  bolt to be
straight, thus avoiding cross threading.

If threading a bar in a lathe, it is usual to bevel the end, and remove
sharp edges with a file, say, or if a quantity of them, by tumbling.

For common, mass produced  thread-rolled bolts, the rolling process does
not normally leave sharp edges at the bolt end (and the end is recessed,
unless shaped for a specific application, e.g, shaft locking socket screws.)

Bottles and caps, also have to be easily removed from the mould. there
is usually a 'skirt' on the cap, and a short plain end of the top, to
allow it to be more easily aligned.

Large diameter, fine pitches are easy to cross thread, if you do not
know the technique, (for example the threads those holding a wheel hub
to the vehicle axle (and some hubs on some vehicles, often have lh
threads, to add to the novices fun...)

I've never heard of Bigbee, I think it is merely the manufacturer of
bolts/machinery, like GKN. Not mentioned  in my 1990 Machinery handbook,
so get the guy to send you a decent drawing.

Whatever single solution you use, it will be wrong for many applications.

On 19/02/2023 22:09, Adrian Mariano wrote: > Is there anybody out there who is an expert in threading with a deep > understanding of how thread ends should be formed? It depends somewhat on the the way the bolt or stud is manufactured, and its final application. For example, the screws that hold a switch plate to the wall box, will have a short length at core diameter, so that it can 'find' the tapped hole in said box, and allow the  bolt to be straight, thus avoiding cross threading. If threading a bar in a lathe, it is usual to bevel the end, and remove sharp edges with a file, say, or if a quantity of them, by tumbling. For common, mass produced  thread-rolled bolts, the rolling process does not normally leave sharp edges at the bolt end (and the end is recessed, unless shaped for a specific application, e.g, shaft locking socket screws.) Bottles and caps, also have to be easily removed from the mould. there is usually a 'skirt' on the cap, and a short plain end of the top, to allow it to be more easily aligned. Large diameter, fine pitches are easy to cross thread, if you do not know the technique, (for example the threads those holding a wheel hub to the vehicle axle (and some hubs on some vehicles, often have lh threads, to add to the novices fun...) I've never heard of Bigbee, I think it is merely the manufacturer of bolts/machinery, like GKN. Not mentioned  in my 1990 Machinery handbook, so get the guy to send you a decent drawing. Whatever single solution you use, it will be wrong for many applications.