Some positions cannot be resolved due to joint conflicts - Linkages

[flex2022]

Dear all,

I am trying to prepare an arm with linkages as shown below (Fig.1):

Fig 1 - Arm being designed

I am unable to join the links with the connecting plate (peanut shaped) on the left side of the arm, its throwing a warning (Fig.2). Surprisingly, it worked fine on the right side. 

Fig 2 - Warning

I tried aligning parts before using the "Joint" feature to make the assembly, the components stay in the same position even after using the "Align" feature. 

Although I'm proficient in SolidWorks, I'm new to Fusion360. Any help is highly appreciated. 

Many thanks,
Raj  

[laughingcreek]

sometimes the joint solver just gets overwelled.  hard to say looking with out seeing the model.  but I would start by removing every pin (except one), unpin, align, move, and position capture in your timeline.  and then post the model for someone to look at.

[flex2022]

Dear @laughingcreek,

Thanks for your advice. I am redoing the assembly just the way you mentioned. However, I had a few questions in doing so,

1. Do you recommend ticking the capture position box every time I align components? Or just say yes whenever it prompts me to?    

2. Does having too many captured positions in your timeline cause any issues?

Heartiest thanks,
Raj

[laughingcreek]

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@flex2022 wrote:

...1. Do you recommend ticking the capture position box every time I align components? Or just say yes whenever it prompts me to?    

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you don't want position captures to remain in the timeline.  Sometimes it's useful to have it there while applying joints just so the components are held in a position where you can get to the right spots easily.  But delete them from the time line immediately after .

...2. Does having too many captured positions in your timeline cause any issues?

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Yes, they can cause many issues.

[laughingcreek]

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@flex2022 wrote:

.. every time I align components?...

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don't use align (or move) on components to position them.

there are 2 viable ways to position a component that don't inherently lead to difficulties-

1-build component in place, and joint with an "as built" type of joint (building in place does NOT include using align or move)

2-join with a standard joint 

there are other ways to get a component into position, but they all lead to heart ache.

[John_Wright]

The joint solver getting "overwhelmed" is a great way to put this. I have seen a few instances where joints (that should work) report an error, only to work correctly when the order that the joints are done in the assembly is changed.

I would suggest using joints rather than using "Align" and "Move" will result in a cleaner and better model overall. Certainly don't rely on "capture position" as a way to move geometry around.

Can you attach the model so others can have a look at it to see if there is anything obvious that would cause an issue. 

[flex2022]

Thank you @laughingcreek and @John_Wright for your support.

It was great to learn from you. I will try to rebuild the joints following your advice and update soon.

I have attached the file if you would like to take a look. 

Thanks,
Raj

[laughingcreek]

start by deleting all aligns, moves,  pins, unpins, joints, and position captures from your timeline.  post that file and we'll move on to next steps.

[flex2022]

Thank you @laughingcreek. 

I truly appreciate your suggestion and I gave it a try but could not succeed.
I realized that I my approach of building all components in a single file was slightly overcomplicated for a novice (me). Contrary to this, I have now created each component separately and tried assembling in a dedicated assembly file (Image 1). I also tried grounding the components to join and then deleting the pins, unpins, captured positions, etc soon after. Unfortunately, I am still struggling with the same error. 

The edges I need to join are highlighted in Image 2. I will be grateful if you could check the assembly file for any errors and suggest a good practice to join linkages.

Many thanks,
Raj

Image 1:

Image 2:

[jhackney1972 · Accepted solution]

I will let the Screencast show you where your error is.  I broke all the links in your assembly so I could send it back to you as one file.  This will allow you to see your error, following the Screencast, and not mess up you linked file.  In the Screencast I stopped after fixing the error but in my attached model I went on and added Joints to the top arms as well.

[evanp4509U4JZ]

Jay, I think the real problem is with the floating link in the middle of the RUL RLL arms. From your edit I noticed the sketch was at the location of the base bracket. The hole center to center distance there, as well on the other bracket is 67.082mm. The hole center distance is 67.08 on the floating bracket that looks like a motorcycle chain master link. I think that is what is causing the pinch in the RUL, RLL arms at the middle bracket end.

Always willing to learn so if I'm out in left field please let me know.

[evanp4509U4JZ]

John. Sorry.

[jhackney1972]

You could be right, I did not worry about that link.  All I focused on was getting the model to animate as it should and if you downloaded my assembly, you can see it animates just fine.  The first thing I found was the hole misalignment in the central plate, it worked after that correction, so I let it go at that. 

[flex2022]

Hi John,

Thank you for your contribution. It did solve my problem.

I should have paid close attention to the distances between the attachment holes. 

Kind regards,
Raj 

[flex2022]

Hi Evan,

You are right! I realize the distance between the two attachment holes is not consistent throughout (attached images). 

Thanks for bringing it to my attention. I shall pay close attention to the distances while working on linkages.

Kind regards,
Raj