1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

How do I align a tube to a spoked wheel?

Discussion in 'Using Alibre Design' started by eron, Jan 3, 2020.

  1. eron

    eron Member

    Hello! I am trying to constrain a pulley to a spoked wheel in an assembly. The problem is that the spokes are not in plane--they are conical/dished. I need the inside edge of the pulley to rest on the outside of each spoke.

    When the spokes are in plane, I accomplish this with a tangent constraint on the spokes or by creating a plane tangent to the spokes and aligning to that. When the spokes are angled/dished as shown, it is not as simple and I have not found a good solution.

    The screenshot shows the objects that need to be constrained.

    Thanks!
    Eron constrain tube to cone.png
     
  2. JST

    JST Alibre Super User

    Align can be to an edge, a planar surface, or a hole, and can be to geometry such as an axis, or a plane inserted. It can have an offset from a surface, etc. Lots of options (that may involve some calculation, depending).

    You need a mounting means to attach to the spokes, and that will involve an alignment, as well as mounting surfaces, so I think you should have no problem if you design that part first.
     
  3. Lew_Merrick

    Lew_Merrick Alibre Super User

    Hi Eron -- It looks as if you have a decent start on things. I assume that the "smaller/darker wheel" is a pulley of some kind and that you want it coaxial with the "larger and lighter wheel"'s axle and have it "clocked" to rotate with the "larer and lighter wheel." So, other than finishing out the "pulley mounting hub," it becomes a case of turning on the "reference geometry" for the "pulley" and the "wheel" so that you can Constrain them rotationally. ??? -- Lew
     
  4. eron

    eron Member

    pulley with j-bolts.png Hi JST and Lew, thank you for the responses. The pulley uses six hooked "J" bolts to mount to the spokes but I am trying avoid modeling that level of detail. The pulley is indeed co-axial with the larger wheel. The problem I have is mating it to the spokes. I can move the pulley close and align it by mating/aligning with the XY plane and using the approximate value but that is not exact and it will not stay aligned when the wheel parameters change (number of spokes, diameter, angle, position, etc).

    Here is another try with the J-bolts modeled. The pulley still will not align to the spokes on the Z-axis. In the real world, the nuts on the bolts would be tightened until the pulley edge rests against the spokes. In Alibre, I'm not sure what the equivalent would be.

    I am thinking I will probably have to create a reference plane in the wheel model using some trig to calculate the offset based on the spoke radius, angle and pulley inside radius.
     
  5. idslk

    idslk Alibre Super User

    Hello eron,

    can you share the package? How will the assembly look if it is completed (i think there are some parts "missing")?
    I think you should constrait the straigt portions of the hooks to the holes in the pulley and the ends of the straigth portions a flat face of the pulley and after this the round portions of the hooks can be constraint to the spokes.

    Regards
    Stefan
     
  6. eron

    eron Member

    Hi Stefan, I could mate the flat ends of the hooks with the pulley surface but then the pulley would be interfering with the spokes. Here is the package.

    When complete, the assembly will look like this image. The Z position of the other parts depends on the position of the pulley relative to the spokes (along Z axis).
    pulley with j-bolts2.png
     

    Attached Files:

  7. Lew_Merrick

    Lew_Merrick Alibre Super User

    Hi Eron -- Would this make things better??? -- Lew
     

    Attached Files:

  8. idslk

    idslk Alibre Super User

    Hello eron,

    here only 2 pictures 9" and 12" configuration
    upload_2020-1-4_0-35-35.png

    upload_2020-1-4_0-36-6.png

    It holds the touch between spoke and hook:) (and also the position to the pulley and the center axis...)
    It got late here in Germany, so i've done it only for one spoke...if i can spare a little bit of time tomorrow, i will make a clean model and post it. It's a little to difficult to explain...

    Regards
    Stefan
     
  9. eron

    eron Member

    Hi Lew, I am not sure how that would improve things but I appreciate the effort! The background on this project is that this motor and pulley system retrofits to almost any existing spoked steering wheels. The pulley and J-bolts are already designed and the Alibre work is for calculating belt size and clearance issues. The clearances are based on where the pulley sits on the spokes (Z-axis) and make the assumption that the user will center the pulley when they install it.
    Eron
     
  10. eron

    eron Member

    Hi Stefan, I would be interested in seeing how you did that. In practice, these hooked bolts tend to rotate depending on the diameter of the spokes, so they aren't perfectly square. I am still wondering if there is a way to mate/align/tangent the inner edge of the pulley with the spokes so they touch but don't interfere.
     
  11. idslk

    idslk Alibre Super User

    Hello eron,

    the package is appended to this post. I've added some planes and an point i need to constraint...
    hope i
    upload_2020-1-4_15-22-51.png

    here a dynamic hoops cut
    upload_2020-1-4_15-23-28.png

    If you move the wheel, it takes a tiny moment(depends on your pc power;-) to regenerate the circular pattern of the J-bolts...

    But an other question, how do you think the pulley will be held in position to the axis of the Wheel in real world?
    Are you going to add some bearing or something like that?

    Regards
    Stefan
     

    Attached Files:

  12. oldfox

    oldfox Alibre Super User

    Hi Stefan.

    The pulley will be radially centered to the helm by virtue of the J-bolts circle having a fixed radius.They would have to be able to
    move in and out (variable distance between each bolt) to not be centered. And the pulley would be fixed axially to the helm by virtue of
    the J-bolts insertion depth in the pulley. Eron wants the pulley in contact with the spokes. ;)

    Happy New Year,
    Chris
     
  13. idslk

    idslk Alibre Super User

    Hi Chris,

    Happy New Year to you and your family as well:)
    Do you mean like this:
    upload_2020-1-4_19-30-52.png

    Hm, well looks like a watchmaker solution...:D
    If it is to motorize old equipment...

    Regards
    Stefan
     
  14. oldfox

    oldfox Alibre Super User

    Thanks. Hope it's a good year for everyone.

    Yes, exactly. Just like you'd do it in real life. "Make it fit.":)

    Well , I don't really know about that, but it is a retrofit. "Motorizing" it would take the load off
    of the helmsman.

    Eron uses the term "Clipper 48". I'd be interested in seeing a picture of the actual vessel.

    I was also thinking about a slight cylindrical cut in that inside edge of the adapter ring at (in this case) an 8.00 degree angle.
    Then an align should work just fine. Could be done with one plane and one axis. Axis for rotation of the cut.

    There's always more than one way to skin a cat.
     
  15. idslk

    idslk Alibre Super User

    I thing i should have read the complete filename more attentive...:rolleyes:
    i've been caught in the "CAD world" to much...
    Now i'm also interested in seeing a picture:)
    can't read the last sentence out loud without scaring our two "roommates" here:D
    Regards
    Stefan
     
  16. oldfox

    oldfox Alibre Super User

    :cool:
    Gonna be a good year, eh?:cool:
     
  17. JST

    JST Alibre Super User

    I think the requirement to adapt to any angle, length etc of spokes might make the j-bolt constraint somewhat variable, and it might not work for every case without errors. You would be using tangent, and tangent can be a bit tricky.

    If, instead, you align the pulley on the axis, and use an equation to set the distance the pulley is away from the hub, based on angle of spokes (trigonometry), and hub dimension, etc, then it should work for every reasonable combination just by changing the dimensions.
     
  18. idslk

    idslk Alibre Super User

    Hello colleagues,

    i've added more planes, an axis and an point and now it works without any offset in constraints (and of course without calculations...)
    Have fun!

    Regards
    Stefan
     

    Attached Files:

  19. bigseb

    bigseb Alibre Super User

    Maybe overthinking this?

    You want to align one 'wheel' to another, yes? There's no need to align the holes to the spokes. Just create reference geometry on both wheels and use that.
     
  20. idslk

    idslk Alibre Super User

    Hello Sebastian,

    sounds easy if you have only two straight wheels with a certain distance...
    but one thing that eron wants, is to position the pulley to the spokes of the wheel to get the correct position for the motor and the rest...
    The pulley seems to have two different diameters(2 configurations 9" and 12") and due to this different positions on the "shaft".
    Another thing is to position the j-bolts to the spokes (if this is neccessary or not, it's for the completeness).

    Regards
    Stefan
     
    JST likes this.

Share This Page