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Proper way to make angled ends on tubes

Discussion in 'General Discussion' started by madsci, Oct 3, 2020.

  1. madsci

    madsci Member

    This might be two different issues, but they're both problems that I run into a lot and struggle with more than I think I ought to. I can make it work, but there has to be an easier way.

    What I'm trying to do is to fit the highlighted diagonal (on the XY plane) into the assembly. The height of the pillow block bearing on the upright is fixed. What I'd really like is to be able to insert a parametric piece that would automatically adjust its length and angle as the rest of the structure changes. I really don't know how to even begin to approach that or if it's a good idea.

    Adjusting the length manually is OK for now. I can get the distance from edge to edge of the horizontal pieces so I know how long the outer side of the diagonal needs to be. Where I get stuck is trying to make the diagonal with angled ends. For 45s (like the shorter diagonals on the Z axis) I can use the angle/distance chamfer, but I don't know how to do that for other angles short of doing the math myself and there must be a simpler way.

    I've done it in the past by inserting planes at the ends and doing extrude cuts to remove material, but that seems clunky too.

    So, two questions I guess. 1: How (and when) should I figure lengths and angles for a member like this that's entirely driven by other dimensions in the assembly, and 2: What's the best way to put exact angles on my square tubes? (Preferably such that it works on hollow tube models, too.)



    Attached Files:

  2. albie0803

    albie0803 Alibre Super User

    It could be scripted where you tell it the end face, an edge and an angle but in the end, what you are doing is probably the fastest.
    madsci likes this.
  3. Hunter

    Hunter Senior Member

    Have you tried Global Parameters?
    Drutort likes this.
  4. HaroldL

    HaroldL Alibre Super User

    You could Insert>New Part into your assembly and use interdesign relations to control the new part.
  5. DavidJ

    DavidJ Alibre Super User Staff Member

    I am away from my computer, so have not reviewed your file. I find that applying draft to an end face gives a very controllable way to angle an end. Careful choice of the neutral plane for draft can make setting length much simpler.
    Drutort likes this.
  6. idslk

    idslk Alibre Super User

    My first impression was obviosly: AlibreScript.
    Then i thought that it might be interessting to go another way.
    So i tried to use somekind of "Mastersketch" and WizoGrid...(first time...)
    I've used a mastersketch due to i don't want to calculate angles and length, so i've drawn them instead (having CAD and not MATH...)
    It is not so accurate made (it should be only a try...) but enough to show an intention...
    The mastersketch is made out of reference lines to have the geometrical "skeleton". The dimensions are important for the rest, so the names should be meaningful (a least to me ;-)). The mastersketch can be drawn "anywhere in space"...
    Then i made new parts in the assembly context (I've let alibre ask me every time for a name for the new part and gave them names!)
    Again i used names for the equation editor values.
    I used WizoGrid to read all this values, calculate the missing ones and also arranged a area to input values to steer the design.
    As i said it isn't well structured and clean, but you can play with it...(There is no validity check for the entered values, no write protection of the table...)
    Dont forget to start WizoGrid ;-)
    What do you think?



    Attached Files:

    Last edited: Oct 4, 2020
    madsci likes this.
  7. Nick952

    Nick952 Senior Member

    I think that the "Top-Down" design Methodology for the diagonal, is what you are looking for.

    Last edited: Oct 4, 2020
    madsci likes this.
  8. JST

    JST Alibre Super User

    What I have done is to make the angled part too long, then insert it, lining it up as desired with the others, but generally behind it.

    Then I "edit here", and project to sketch from the other parts, cutting the new part as needed. That way it fits.

    Too many interdesign relations has seemed to make assemblies slow and unstable, so I tend to avoid them unless the features are very difficult to produce any other way, and would be very hard to edit in case of changes.

    When doing this with round tubes, and coping them, it is necessary to do the cuts from the end, depending on what the assembly looks like.

    In general, coping and constraining round tubes, as for fabricating handrails on stairs, etc, is one of the clumsier operations in Alibre.
    madsci likes this.
  9. madsci

    madsci Member

    How would I do that with global parameters?
  10. madsci

    madsci Member

    Ah, thank you! I redid the diagonals as a loft and it worked well. Kind of moot at this point because I already finished most of the welding today (only stopped because I'm out of gas and can't get more on a Sunday) but it's always good to have a drawing for reference regardless. And there's still plenty to be done on the seat portion.

    Attached Files:

  11. madsci

    madsci Member

    Hi! I'd never heard of WizoGrid. I'll have to take a look. It's a lot to take in... I'm a pretty casual Alibre user and haven't really looked at add-ons. (Aside from VisualCAM, which turned into $1600 of regret.)
  12. NateLiqGrav

    NateLiqGrav Alibre Super User

    Interesting assembly. May want brakes on it.
  13. madsci

    madsci Member

    Yeah, that's on my list of things to try to accommodate in the design. Not sure it'll be necessary - it's based on this version, and I talked to the guy who built it about various operational issues and it sounds like they've never needed a brake.

    It might get a little complicated to implement. Each axis would need a brake, and you can't really run brake cables through the axles. It's going to have motion-reactive LEDs all around it, and those are going to run on batteries and communicate wirelessly to avoid having to pass any electrical signals through the rotating joints.

    It will have a lock, though. It's important to be able to hold the seat stationary while boarding, and I also need to be able to put a padlock on it.
  14. HaroldL

    HaroldL Alibre Super User

    Is there a version of WizoGrid that works with v21? The one I have won't load and errors stating that it only works with v20.:(
  15. Ralf

    Ralf Alibre Super User

    Last edited: Oct 5, 2020
  16. HaroldL

    HaroldL Alibre Super User

    Thank you Ralf.
  17. HaroldL

    HaroldL Alibre Super User

    Is there an installer for Wizogrid? If I try to run it I get a Windows warning:

  18. Ralf

    Ralf Alibre Super User

    Yes Harold, please click: More Info
  19. HaroldL

    HaroldL Alibre Super User

    So then I take it that I click the Run Anyway button? This is the first time I've seen this "new" warning from Windows. It must be new with the latest feature update to version 2004. :confused:

  20. albie0803

    albie0803 Alibre Super User

    No it's been around a while. As it says, it's because the publisher is not registered with microsoft.

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