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  1. #31
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    I was wondering how long it would be until you secured your own printers

    Those are some excellent prints indeed. Nice to see someone pick up some tips rather than just prints.

    In CAD, if the sweep is following a "string", the section normally stays normal to the sweep string.
    In the case of threads, that section should remain parallel to the axis.
    That is how I keep my radii tangent throughout the sweep.

    Tapered thread for an over-sized pin-vise.

    Oh, one other tip... I always "core" my screws. This makes them twice as strong. A hole will do. The 1/4"-drive hex was convenient in the 1/2" offerings. Even the revised post has a core connected at both ends. I just closed up the build-plate end for adhesion's sake.
    Last edited by TommyDee; 11-17-2018 at 04:24 PM.

  2. #32
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    I was looking at decent cheap printers (even bid and missed out on a couple of Cube 3s on Ebay). I decided on a Creality Ender 3 but then I stumbled across an Anycubic Kossel Linear Plus on eBay with a "Best Offer" option and the seller accepted my offer! I have been fascinated by the mechanics and software of delta/kossel style printers since I first saw them a few years ago, I even started buying some parts (belt and pulleys...) to build my own back then but never got any further than that.

    That took care of my delta fix but I still needed a cartesian style printer... Well, long story, I got the Ender 3 also on a best offer on eBay not too long after... Excessive? Maybe... Worth it? Every penny!

    I like both of the printers but it has taken some work to get the quality/ease of printing close to that of the EkoCycle. Most of it was figuring out slicer settings for each printer but also some mechanical and firmware upgrades. I do enjoy tinkering with stuff though so I went in to the purchases expecting to have to tinker and I have not been disappointed.

    --Insert a few hours of Fusion 360 distraction--

    --Resume Post--

    I played with fusion and sweep a little more. Here are a couple of screenshots of my helical path and then sweeping a simple rectangular profile along it:

    HelicalPath.jpgHelicalSweep.jpg

    And then with a helical guide rail:

    HelicalRail.jpgHelicalRailSweep.jpg

    So far so good.

    Now when I try to make a custom profile to sweep (i.e. the thread pattern) I start getting all sorts of errors about planes intersecting each other and face-plane misalignments and other "Sorry can't be done" kind of errors... I did find however that if I hide my cylinder body the sweep works just dandy. I can then un-hide my cylinder and everything looks good until I try to join/combine the two bodies (newly created sweep profile body with cylinder). Resume endless error messages... I then discovered that if I go to the mesh tab in Fusion and create a mesh of the cylinder and another mesh of the swept profile body and then combine them in the mesh environment all is well!

    Voodoo.jpg

    That sure is a lot of work though and seems a little too voodoo magicy for my sensibilities. I am going to play with creating a custom cut tool that I can apply to a body and make the male and female threads all at once. I suspect it is going to be a royal pain and I am certain I will discover new and creative ways to break Fusion but I have always been somewhat of a sucker for punishment...

    Excellent tip on coring the bolts, with excellent motivation! Will be done.

    Now I need to figure out a project that requires nuts and bolts so I can apply all my newly gained knowledge...

    Ooooooo, over-sized pin-vise... Color me intrigued!

    Tommy, if I have not said it yet, THANK YOU for all your time, models, guidance, tips, help and inspiration. I truly appreciate it all.

  3. #33
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    All those trials and errors are -very- familiar to me. Creo has serious limitations on any kind of sweep with fails in the 90 percentile.
    Operating on these sweeps too generates higher levels of frustrations.

    I've also seen the "rolling" profile and have to use the same technique to manage section orientation.
    You haven't clarified if you have the section parallel (sketch plane through) the axis.
    If you section that square thread along one of the world normal planes, does it result in a true square thread element? ...or is it in fact a rectangle in a normal section?
    Most likely your section is running normal to the sweep trajectory. This means that your 3mm pitch requires tilt compensation in the sweep section.

    So the tip for Creo users is this... Make the thread(s) first. Immediately join with a solid extrude or revolve! The feature -must- extend to or beyond the helical sweep regardless of feature type. Now you can operate on the newly created threaded mass. Rounds will still fail often. Revolve cuts for thread chamfers or fills seem to work okay.

    The inner working of the code that merges solids is where the problem comes in. The helical sweep is a long solid ribbon that can even have overlaps. The extrude encompassing the helix hides those seems from processing. This makes the model manageable.

    It is the above reasons that I put the extra effort into a highly integrated comprehensive parametric sketch.

    I am able to do today what people have said for decades will never be possible with the Helical Sweep feature in Creo.

    Tapered thread... try a 1.5 degree taper.

    - - - - - - - - - -

    Another challenge in CAD - Modius

  4. #34
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    I sketched the profile section on a plane that is perpendicular to the face of my cylinder. (bottom of clylinder is centered on the origin and extruded up along the z-axis, profile is sketched on a plane formed between the z and x axis, i.e. perpendicular to the y plane). Hope that makes sense.

    I tried at one point to sketch the profile section on a plane perpendicular to the path of the sweep but that resulted in similar issues so I haven't looked at it again.

    So, let me see if I am understanding: Tapered thread... am I trying to put a thread on a cone that has a taper of 1.5 degrees?

    And when you say modius do you mean mobius? Either way I am lost.

  5. #35
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    Mobius... ha, yes...

    Yes, if F360 swept that profile remained oriented to the ZX plane, that would be correct. A section view (drawing) through that plane should let you confirm it with dimensions.

    Half angle at 1.5 degrees.

 

 

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