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bnguyen-212-Amethyst
12-Amethyst
January 22, 2014
Question

Timing Screw

  • January 22, 2014
  • 3 replies
  • 20182 views

Dear

I see one function to design Timing Screw is good

https://www.youtube.com/watch?v=gdRKmJHwPvI

How in Creo have this function:

The fuction is not sweep or Var section sweep

This function is: Sweep with variable pitch cut from one extrude body (In creo just sweep from section, this is sweep cut from body)

Please help & discuss how to do in Creo

Thanks & Regards

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3 replies

T
23-Emerald IV
TomU23-Emerald IV
23-Emerald IV
January 22, 2014

You should be able to create a graph to change the angle (rotate) the section as it moves down the trajectory.

T
23-Emerald IV
TomU23-Emerald IV
23-Emerald IV
January 22, 2014

Here's a quick example of what I mean.

screw.PNG

    T
    TomD.inPDX17-Peridot
    17-Peridot
    January 22, 2014

    If is follows a constant angle change of the "tool" it could be a variable section sweep using trajpar along a spiral guide path (origin). The path would incorporate the pitch variation, if needed, by wrapping a sketch onto the cylinder.

    T
    TomD.inPDX17-Peridot
    17-Peridot
    January 23, 2014

    I have worked on a problem like this before and found that core Creo does not do this very well at all. It can do a 2D cut with ease with many options, but to remove a 3D tool, even something as simple as a ball end mill, it simply doesn't work right. I suspect you need the manufacturing extension to get this right, and even with that, I am not sure you can get this result.

    T
    TomD.inPDX17-Peridot
    17-Peridot
    January 23, 2014

    This might make it clear or just muddy the waters... but if I extrude any section along Tom's model, it removes more material. This would happened continuously along the entire path.

    errand_tool.PNG

    If this can be done in core Creo without faceting the cut surface, I would love to know about it.

    This is a very real condition anytime you add a mill to a rotating cylinder. Think about a grind wheel that is machining grooves into a cylinder mounted to a lathe. How would you do that?

    D
    dschenken1-Visitor
    1-Visitor
    January 23, 2014

    I think this form can be generated by single point cutting. Mill out the bulk of the material and then single-point the remainder.

    A flat bottom cutter won't work anyway as the the angle between the walls and the bottom changes from 90 degrees.

    Patriot_1776
    Patriot_177622-Sapphire II
    22-Sapphire II
    January 30, 2014

    It appears solidquirks can sweep a solid body along another solid body as a cut. something Pro/E should have been able to do long ago. You can sweep cuts in Pro/E, sure, but the geometry you get will not be what a real cutting tool will create. Sometimes it's close, sometimes not. This thread is a perfect example of why we need this. So, PTC, how about quit monkeying with the GUI and give us features we can use?

    http://help.solidworks.com/2014/English/solidworks/sldworks/hidd_dve_feat_sweep.htm

    http://help.solidworks.com/2012/English/SolidWorks/sldworks/HIDD_DVE_FEAT_SWEEP.htm

    http://www.youtube.com/watch?v=xKNle2zi7qA

    T
    TomD.inPDX17-Peridot
    17-Peridot
    January 30, 2014

    I would think that the manufacturing extension does this just fine. Problem is, we as engineers are trying to tell manufacturing what to do but not how to do it. Not allowing core Creo to create an accurate model for these processes is a huge oversight in my view. It is a rare occurrence and certainly doesn't justify buying the manufacturing extension for 99% of users. Therefore, PTC's logic puts the cart before the horse and thereby creating a communication breakdown between design intent and fabrication.

    Patriot_1776
    Patriot_177622-Sapphire II
    22-Sapphire II
    January 30, 2014

    I agree. I believe WE the Designers and Engineers need to be able to 100% describe the geometry we want, and will get using a certain 3D shape (not 2D section), and that Pro/MANUFACTURING should only need to do whatever tool geometry and toolpath are needed to get that geometry. If we cannot produce the geometry we need on our end, how can we, at the asembly level, know if the geometry will work? These timing screws are being used essentially as barrel cams, so how could we accurately predict if the follower (roller follower, bottle, etc.) is able to follow the path we want?

    I'd much rather be able to create the correct geometry, than have the manufacturing people have to guess what we really want.

    If SW has this capability, Pro/E certainly should......and should have had it FIRST, to justify our spot on top (in price). But, hey, we DID get the ribbon instead, so.......

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