Equal Length Constraint in Assembly

[IT_10439331]

I would like to make these linkages move together, the easiest way to do this as I think is making the distance from the origin the same for the links (indicated by the lines drawn). However, I am unable to find a way to do that, any and all help would be greatly appreciated. 

*I am using PTC creo parametric 9.0 student edition

[MartinHanak · Accepted solution]

Hi,

see video.

[IT_10439331]

Thanks for the reply but I am not sure how to constrain the sketch to the links in assembly, I would appreciate it if you could guide me further. 

[IT_10439331]

After working around with this, this actually works perfectly fine, thank you for the help. 

I currently have the sketch placed like this in the model tree so I can define the subassemblies and parts based on the sketch, however this means I cannot use "drags components" anymore since they are not free to move, do you have any tips regarding that?

Much thanks,
Ibrahim

[MartinHanak]

Hi,

I do not understand why do you want to drag components. Draging is available when assembly components are assembled using mechanism constraints.

Please explain how do you want to move components - show it using picture with arrows.

Q: Modification of sketch dimension is not enough?

[IT_10439331]

The assembly is connected via Pin Connections at the "holes" (image attached), I have attached two images where I change the sketch dimensions and the result (which are perfectly fine). I am wondering if there is a method to drag the components to achieve the same result.

I am a university student trying to learn creo, modifying sketch is definitely an acceptable solution to what I asked, it is just out of curiosity I am asking if dragging components can be used.

[IT_10439331]

I am attaching a picture of what I had hoped to and have achieve successfully geometry wise. Many thanks to Martin.

[MartinHanak]

---

@IT_10439331 wrote:

The assembly is connected via Pin Connections at the "holes" (image attached), I have attached two images where I change the sketch dimensions and the result (which are perfectly fine). I am wondering if there is a method to drag the components to achieve the same result.

I am a university student trying to learn creo, modifying sketch is definitely an acceptable solution to what I asked, it is just out of curiosity I am asking if dragging components can be used.

---

Hi,

I am not expert in case of mechanisms ... therefore I do not know if dragging components can be used.

However, after a bit of searching, I figured that your model would have to come up with connections between components.

An example of connection is shown in https://www.youtube.com/watch?v=Vmihj3Il0UY video.

Also I downloaded runner.zip from https://community.ptc.com/t5/3D-Part-Assembly-Design/Simultaneous-Mechanism-Motion/m-p/147567#M11399 discussion ... see uploaded video.

[MartinHanak]

Hi,

I think you can use Cam-Follower connection to move 5 "points" simultaneously by rotating shaft with 5 cams.

https://www.youtube.com/watch?v=tfob1bF6Pxg

[MartinHanak]

Seee attached video showing test model.

[IbrahimTayyab]

I had a realisation that the length can be maintained by using constraints on the angles in the geometry. I started this sketch and it helped me a lot (Sketch image below), I realised the chord would be an isoceles triangle with angles highlighted being 54 degrees regardless of length. So I made planes defined on the part at 54 degrees from the 0 degree (planes image below), by constraining the that plane to the corresponding previously placed piece's plane I can ensure they move in tandem (planes constrained image below). 

I am also attaching a video of it working and the constraints used for posterity (constraint video below), I realise the menu has not been recorded, hopefully, the highlighted planes are enough to understand what is going on.

 

Martin you were a tremendous help, your replies motivated me to delve more into the forum and think deeply on the ways this could be achieved, I also really appreciate your help (for example downloading the runner file for example and uploading it working since I cannot directly access the file with the education version), I am blown away by your kindness and thoughtfulness. Thank you very much for your help

[IbrahimTayyab]

I am attaching my assembly for posterity, hopefully it can be of help to someone.

[IbrahimTayyab]

That is very interesting, I was meaning to get into trying out cams and followers, this is a perfect opportunity to dive into it, thank you very much.

[IbrahimTayyab]

I thought you might be interested in knowing what it all ended up as, I have attached a video. I used a cam connection on the hanging out bit ( i am not sure what to call it) and the wedge. The cam is supposed to be a conical cylinder, I am working on changing it.

Best,
Ibrahim

[MartinHanak]

Hi,

it seems to me that it is better to add video as attachment instead of embedding it.

[IbrahimTayyab]

I apologise for the hassle you are right. The constraint video shows the constraints and the initial assembly. The video named complete shows well the almost completed assembly