How to design cone caps?

Discussion in 'Tips, Tutorials & Tools' started by bigpetr, Nov 14, 2016.

  1. bigpetr

    bigpetr Designer/Master Modeler

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    Hello friends.

    On FIGURE 1 is model of tube (red part) with diameter TD (tube diameter). I want to make it from 160gsm paper with thicknes PT (paper thicknes cca 0.2mm for 160gsm paper??). If I want paper tube to have diameter TD do I need to adjust TD for unrolling to flat pattern?

    If I want a cap (blue part) like on FIGURE 1, will be CD (cap diameter) same as TD or should it be smaller like hinted on FIGURE 1?

    Same question for FIGURE 2. I have model of tube with diameter TD and I want paper model of that tube to have inner diameter TD. How to adjust TD for unrolling to flat pattern? And what should be diameter of hole in blue part?

    Or am I overthinking it? Do you even consider paper thicknes when designing?

    tube design.jpg

    Thank you or your answers:)
    Last edited: Nov 14, 2016
  2. zathros

    zathros -----SENIOR---- Administrator Moderator

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    I do not think of paper thickness except when that thickness adds to accrued intolerance. When making caps like you are doing, for tops, you could use "Caap Planar Holes" under "Solids", or click on the boundary of the inner circle and select "Patch" from the "Surface" commands. If you do not have a boundary, from the Curves command, select "Duplicate Edge", you should play with that whole command system as there are many many tools that make Rhino useful. If capping a whole like that, one should realize that a persons modeling habit will determine how the part fits. If you have "Display Curves' when you render a part, and they cut off the Black curve, the part will naturally be smaller than the whole. In a perfect world, a 1 mm cap will not fit into a 1 mm hole, right? :)
  3. bigpetr

    bigpetr Designer/Master Modeler

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    Thak You Zathros. I know how to model it, that is not what troubles me.
    This is my trouble: I considered paper thicknes when modeling this (like on the picture, because diameter of my tube is only cca 12mm) thinking everything will fit nicely then. But cups are too small for the tube when cut from paper:(. I was surprised how much smaller they are that they need to be. Maybe paper thicknes of 0.2mm I consider is too much for 160gsm paper I am modeling from? I will measure the real paper tube and must corect that on my template. I just wanted to know if there is a way to make it right on first try:).
    zathros likes this.
  4. Gandolf50

    Gandolf50 Researcher of obscure between war vehicles... Moderator

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    Paper thickness is a concern ..yes..but you are going to run into problem no matter what if this is going out to others to be modeled..as no matter how you figure it, the builder will use what is available and all your calculations will be for naught... for example....US is just barely using G/m2 for card stock...most is still in lbs which tells you nothing... 2 different card stocks as 110 lb will give totally different thicknesses! Even the same G/m2 can give you different thicknesses...I have 2 different stocks at 199 g/m2 and they are slightly different .22 and .23 just enough to make your part not fit!

    but none the less 160 G/m2 is going to be around 0.188 or so... try this link...when you need thicknesses... http://www.jampaper.com//images/paperweight.jpg nothing out there is accurate but this is close!

    I would do the cone with a flat bottom and let the modeler fit the ring to the tube and then glue to the flat bottom ! just a thought...
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  5. bigpetr

    bigpetr Designer/Master Modeler

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    Thank You for your answer Gandolf. You are absolutely right. I see it is not safe solution to shorten cone caps diameter by paper thickness because it varies a lot. I looked at some designers, namely Imcold and UHU02, and they both make cap diameter same as cone diameter.
    zathros likes this.
  6. zathros

    zathros -----SENIOR---- Administrator Moderator

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    This is where lamination comes in. Instructions should simply state, "Laminate part to proper thickness for the paper you are using". People make models out of whatever they have. There is almost no way to compensate for that except to trust and teach technique to modelers, which broadens everyone's horizons, and makes things "understood', in other words, "it should look like this, and be as thick as the piece or whatever you state the thickness add, laminate as necessary". Laminating parts allows for hinges to be hidden and can make parts far more authentic. ;)
    bigpetr likes this.