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ptc-31165001-Visitor
1-Visitor
February 24, 2014
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Re curved threads in creo parametric 2.0

  • February 24, 2014
  • 1 reply
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Hello!

Does anyone know the best way to make a curved, threaded rod? I've tried starting with a staight rod, cutting threads in a helical sweep, and then bending the original sketch, and also starting with a curved rod and cutting threads with a helical sweep, and also using a helical sweep to create the shape of the threads around a curve with the last approach being the most successful, but with somewhat sloppy results. I'm trying to model a piece of allthread that I put an approximately 85 degree bend in.

Thanks,

Kevin


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Best answer by TomD.inPDX

Attached is a Creo 2.0 full version of a parametric bent All-Thread. You can tweak the parameters in relations and all the features will update accordingly.

I have tested a few sizes and they seem to keep working. If it blows up, try changing it by smaller steps. The helical sweep tends to get touchy at some point.

For the more advanced users who like to look through these techniques, you will notice I started by threading a rod that is a little longer than the helical sweep profile. Because it didn't over-run the end, I was able to do a tangent/sharp edge in the sweep right on the surface. I also created a revolve cut to chamfer the ends right up to the minor diameter by using the pitch to control the chamfer sketch. The last trick was to let the spinal bend trim the excess from the end. The straight ends of the final part should still follow the original pitch setting. The "K" factor in this case is through the center (0.5). That is the only way to preserve the pitch without some much deeper math. A perimeter dimension in the spinal bend profile is held to the final rod length to remove any stretch or crush of the pitch in the straight end-segments where spinal bend can distort such features.

BENT_ALLTHREAD.PNG

1 reply

T
TomD.inPDX17-Peridot
17-Peridot
February 24, 2014

It is going to be somewhat distorted, obviously, but a variable section sweep should be able to do this with ease.

How much distortion are you suggesting?

In this particular case, I think that spinal bend would be the most accurate method if you want consistent compression and expansion.

T
TomD.inPDX17-PeridotAnswer
17-Peridot
February 25, 2014

Attached is a Creo 2.0 full version of a parametric bent All-Thread. You can tweak the parameters in relations and all the features will update accordingly.

I have tested a few sizes and they seem to keep working. If it blows up, try changing it by smaller steps. The helical sweep tends to get touchy at some point.

For the more advanced users who like to look through these techniques, you will notice I started by threading a rod that is a little longer than the helical sweep profile. Because it didn't over-run the end, I was able to do a tangent/sharp edge in the sweep right on the surface. I also created a revolve cut to chamfer the ends right up to the minor diameter by using the pitch to control the chamfer sketch. The last trick was to let the spinal bend trim the excess from the end. The straight ends of the final part should still follow the original pitch setting. The "K" factor in this case is through the center (0.5). That is the only way to preserve the pitch without some much deeper math. A perimeter dimension in the spinal bend profile is held to the final rod length to remove any stretch or crush of the pitch in the straight end-segments where spinal bend can distort such features.

BENT_ALLTHREAD.PNG

    P
    ptc-31165001-VisitorAuthor
    1-Visitor
    February 26, 2014

    Thanks, guys!

    I ended up using a modified version of the following method

    http://learningexchange.ptc.com/tutorial/2530/creating-a-helical-spring-around-a-non-linear-trajectory

    to get something that was 'good enough'. But, Antonius, your part looks much cleaner than what I ended up with, especially along the bend. I'll have to study the tree along with your explanation to try to figure out what you did!

    Thanks again,

    Kevin

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