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Assembly constraints for basic blocks

hans_bollenhans_bollen Member Posts: 8
edited December 2021 in Community Support
Hallo Onshapers,

I'm new in Onshape and a professional mechanical engineer using 'other cad' for decades, Therefore, I believe I make good Onshape learning progress in one week of time. I know : Learning cad is both trial and error, and reading the manuals. Which really helps. But despite of and probably due to my extensive cad experience, I do not manage to assemble the shelfs in my birdhouse hbinb_00131. What I do expect is assembly constraints touch face to face and align face to face. With 3 of them I can constrain one plate to another. How to do this in Onshape ? I learned in https://learn.onshape.com/learn/article/mating-basics that I only need one mate action. Which one. And how ?


Thanks in advance

Hans


Answers

  • steve_shubinsteve_shubin Member Posts: 630 ✭✭✭✭
    edited December 2021
    @hans_bollen

    https://cad.onshape.com/documents/7497a8ae22e85beec5975064/w/a954dce1efb5f3e682fb1506/e/bb1c9fb3523a43e9d6df1a60

    I EDITED the mates you had. I changed the planar mates to fastened mates

    Now nothing moves as the parts are all fastened (locked) together

    Is this what you were looking for ?


  • tim_hess427tim_hess427 Member Posts: 627 PRO
    "Mates" seems to be one of the differences in onshape that tends to throw experienced people off - so you're in good company. 

    To understand onshape mates better, try to "flip" your thinking. Instead of using mates to build up constraints, start with your design intent in mind. Do you want two parts to be rigidly connected? Use the "fix" mate. It constrains rotation and translation on all three axes. Do you want one part to rotate inside of the other? Use the "revolute" mate (it fixes the two objects, but allows rotation around only one axis). Do you want to allow rotation and axial motion? Use the cylindrical mate that allows rotation and movement along one axis, but the others are fixed. 

    I hope this helps a bit. 
  • dirk_van_der_vaartdirk_van_der_vaart Member Posts: 155 ✭✭✭
    Is there a need to work with mates in this case?
    If you design all the parts in 1 Part Studio you import all the parts in one-click in a new Assembly, just group them and you are ready.
    https://cad.onshape.com/documents/82d46ec4a7639780e81358fc/w/5cb916345a9034c149ad3ad5/e/76752bdc059773fd87bc9d3f
    Have a look.
  • hans_bollenhans_bollen Member Posts: 8
    Thanks Guys, I did spend some time to watch youtube demo's .That really helps. And of course I do like to share my design.

    I dont mind they are all visible in onshape. So we can learn from each other.

    Find my components with searching for hbinb_00*

    Please find my hbinb_00281. components are hbinb_00251 and up. I think this one has proper constraints. Some more questions on this:

    How can I see if all parts are fully constrained ?

    Why are all my parts listed as "Part 1 <x>", why not using my hbinb_00xxn, or some description, defined in the components

    Why is the hbinb_00261 green when loaded as part studio, and the original blue in the list of components created by me ?

    See hbinb_00131 and component hbinb_00031. Why does the hole of the 00051 not show up in the 00131 ?

    Thanks in advance

    Hans

  • dirk_van_der_vaartdirk_van_der_vaart Member Posts: 155 ✭✭✭
    edited January 1
    This is not a Youtube demo, this is a learning video about how to work with Multi-part studio's
    https://learn.onshape.com/courses/designing-top-down-with-multipart-part-studios

  • hans_bollenhans_bollen Member Posts: 8
    Thank you Dirk, I will watch it on sort term.
  • hans_bollenhans_bollen Member Posts: 8
    There are still questionsi in my post un answered ...
  • john_mcclaryjohn_mcclary Member, Developers Posts: 3,445 PRO
    edited January 6
    Using 3 mates is a simple way to understand part relations. But it is very cumbersome and can slow down the performance of a model as well as tripling the effort and clicks of the CAD user.

    Onshape did it differently.  They decided any part should be able to join another part with just a single mate (most of the time at least)

    The way I learned it was to think of each mate type as a restriction of degrees of freedom. Some mates are simply two or more simple mates that are combined into one.

    So:

    Zero Degrees of freedom:
    - Fastened (Parts are locked together as if welded)
    - Group (Parts are lock together as if welded, but their positions are relative to each other wherever they were dragged in an assembly)

    One Degree of freedom:
    - Slider (Parts will not move relative to each other except they can slide along the Z axis of the mate connector)
    - Revolute (Parts will not move relative to each other except they can rotate along the Z axis of the mate connector)

    Two Degrees of freedom:
    - Cylindrical (Combination of Slider and Revolute)
    - Pin Slot (Similar to Cylindrical, except the parts will slide along the X axis of the mate connector rather than the Z axis)

    Three or more Degrees of freedom:
    - Planar (Parts will only move relative to each other along the X and Y axis and may rotate along the Z axis)
    - Ball (freely rotates on all axis around an origin point of the mate connector)
    - Parallel (freely translates on all axis, only rotates along Z axis of mate connector)

    Special:
    - Tangent (allows two surfaces/points/edges to move in all directions as long as the selected references are 'touching)


  • dirk_van_der_vaartdirk_van_der_vaart Member Posts: 155 ✭✭✭
    Hi Hans,
    I took a look at some of your document's, and I still don't understand why you are making life so difficult.
    Each simple part is a single document and sometime's there is only 1 part in an Assembly with no Part Studio in the document.
    Did you take a look at this document?
    https://cad.onshape.com/documents/82d46ec4a7639780e81358fc/w/5cb916345a9034c149ad3ad5/e/42ad65cf41988263abc0dff5
    This a "normal" document for an Onshape user.
    Groeten van een eigenwijze hollander :)
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