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Gear Motion

Discussion in 'Using Alibre Design' started by bobsmodels, Mar 1, 2019.

  1. bobsmodels

    bobsmodels Member

    I looked at some old posts but could find no information.

    I need to be able to make two shafts move at a ratio ie emulate a gear ratio. I have seen it done in other CAD programs. Is there a way to do it in Alibre?

    Bob
     
  2. Lew_Merrick

    Lew_Merrick Alibre Super User

    In a word, NO! I have been "requesting" this (and other "ratioed constraints") since Alibre V10. It should not be that difficult to create. -- Lew
     
  3. JST

    JST Alibre Super User

    I have managed it a couple times, but it is only by a workaround that is a bit unreliable, that seems to run out of range in a couple turns either way. As I recall, it was by putting a feature on each gear, and relating the angles by a negative factor.

    I have not tried it for a while, so it may no longer work. It is an undocumented feature, and never worked the way it ought to.
     
  4. Oldbelt

    Oldbelt Senior Member

    Bob look here GearPair (4).jpg
    Try to chance Angle 2
     

    Attached Files:

  5. idslk

    idslk Senior Member

    ...or let the script do the change;)
    The script turns the gears with the contrains of oldbelt.
    It runs inputed degrees forward and the same degrees backwards...
    It runs also more than 360° if you want to. A negative value reverses the turning direction.

    Regards
    Stefan
     

    Attached Files:

  6. JST

    JST Alibre Super User

    Of course, this SHOULD be made a regular constraint type, and in that case there would be no need for elaborate workarounds.
     
  7. oldfox

    oldfox Alibre Super User

    Hi Stefan,
    I was also working on that motion thing. I took a different approach though. I was wanting to use the script "RotatePart(Name, AngleX, AngleY, AngleZ, Bool) function but it kept erroring out. I just couldn't make it work. Any ideas?

    Thanks,
    Chris
     
  8. idslk

    idslk Senior Member

    Hello Chris,

    Rotate uses an old principle: "Everything in the universe rotates around the earth...";)
    So every part, regardless of it's position in the assembly, will be rotated around the origin/axes.
    If Andy will give as the possibility to choose a different axis, it could be a way...
    For now i dont' have an idea:( (except some funny looking part movements created with rotate:confused:)

    Regards
    Stefan
     
  9. oldfox

    oldfox Alibre Super User

    I just make funny looking parts when I try to constrain to a tangent without thinking (dimensioning) first.

    I have 2 wheels on the XY plane. One is centered on the origin (Z axis) and the other is on an axis i placed at the c/c distance of the 2 wheels.

    I tried one at a time to rotate a wheel and neither one would work and the script errored out every time. The most common error was "RotatePart not defined", I thought it was a function within AlibreScript. Maybe not. So... ditto:(
     
  10. idslk

    idslk Senior Member

    Hello Chris,

    i took oldbelts gear again and made a liitle rotate script...
    As far as i found no way to define a second axis for the second gear to rotate around, it rotates around the YAxis.
    This is only a little example for rotate, it has no deeper meaning...
    Attention! After visually been done, it takes some seconds for a kind of "internally coffee break" where the programm seem not to respond to you.... look at the console to see when it is really done.

    Regards
    Stefan
     

    Attached Files:

  11. oldfox

    oldfox Alibre Super User

    Hi Stefan,
    I'll give it a try and see where I can make it go.
    Thanks,
    Chris
     
  12. idslk

    idslk Senior Member

    Hi Chris (and all others too;)),

    ...i made this (based on @Oldbelt ParametricGearwheel and my own Gear_Motion...)
    It has a moving stick! :) (movingspeed depends on the hubfactor in eqution editor...)
    Open the Package and run the Gearmotion_V02 script...
    upload_2019-3-11_16-27-52.png

    as far as i haven't tested if a script is included in a part file or package, i appended the package and the script also.

    Regards
    Stefan
     

    Attached Files:

  13. oldfox

    oldfox Alibre Super User

    Hi Stefan,
    AWESOME!! Oldbelt and you did it. Now I can put my models in motion for show. I'll go through until I understand it all and then put in the
    prompts for rotation angle (direction), how far, speed etc,

    Again, well done.
    Chris
     
  14. bigseb

    bigseb Alibre Super User

    While its great to see others making headway using scripts I still agree with Lew about these types of constraints being a part of Alibre functionality.
    Something along the lines of (in assembly): if Shaft 1 = 1 rotation ; shaft 2 - x rotations

    +1000!
     
    JST likes this.
  15. simonb65

    simonb65 Alibre Super User

    +1. Totally agree. I know that scripting opens up the scope for individual extensions and automation of the aplication, but the CORE functionality MUST be improved and enhanced for all. Without this core development, the application merely becomes a framework for users to spend their time developing helper functionality instead of actual productive content! To most users, it is a TOOL ... NOT a development platform.
     
  16. idslk

    idslk Senior Member

    Hm?
    As i'm doing nothing productive (you know it's raining money here), i find it amusing to add little helpers to the program.
    So all the productive people can use them until the Big Tool has the same or better functions...
    Maybe it makes more sense to ask for new functionality instead and wait for them to come somewhen.
    I hope that Alibre will implement some of the feature requests, of course...

    Regards
    Stefan
     
  17. albie0803

    albie0803 Alibre Super User

    So I added the two gears as a second set, tied the left pair together and set a parameter (Sorry Lew, a variable) for the angle of the fourth gear and it ran nicely. Looked real purdy it did! I likey!!

    upload_2019-3-12_11-36-17.png
     
  18. bobsmodels

    bobsmodels Member

    All
    Thanks for all the leads, I have been away from my project and will give the above information a try.

    Bob
     

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