a2plus: Constraints inconsistent. Cannot solve System.

[_cyclops_]

Hi,

As i'm fairly new, i'm quite sure the above question has been asked before.
I've been assembling with a2plus and all goes well. Until i hit the Constraints inconsistent error message. It tells me to delete the last added constraint, but that doesn't make it go away.

Is there not a way to find out WHICH constraint is causing an issue or which part of the assembly is not ok?

I've got an wood working assembly with currently around 10 parts. It's a massive pain to start from the beginning again (albeit i seem to have no other option). The problem is, i don't know what causes this, so i'm not looking to just restart. I want to learn what i did wrong and how to resolve an error.

[dan-miel]

Hi cyclops
I asked this question once and apparently the mates are solved as a group and does not output which one caused the problem.
Have you tried using the tool in A2+ that shows what surfaces a constraint is connected to?
It looks like a gray magnifying glass. I have used it to find problem mates although I cannot all ways find them.

Here is a demo.

phpBB [video]

[Smiling_user]

New xample of same problem: onli the first part of all copies gets constrained. The rest are "conflicting" and unresolved.
Win7x64, FC 0.19, A2+ 0.4.47c.

[dan-miel]

New xample of same problem:

It looks like a different problem. as I think this might be what you are looking for. I created a file. Inserted one part then made an array of 10 across at 6 inch's ,5 down at 3 inch's and 2 back at 60 inch's.
Yours's looks like just the x would be needed.
Start with A2plus then insert an array from the Draft workbench.

[Smiling_user]

To summarize the whole discussion:
in the A2P documentation - there is pointed, that solver needs:
1. one imported detail with "fixed Position = true"
2. complete chain of constraints from that detail through constraints and details to the detail to solve constraints for.

The first can be achieved: also with local detail, by { Select + [make native A2P detail] }. Then set "fixed Position = true".

SO: if solver does not move detail, there is mostly a problem either with the constraint chain, or with constraint conflict.

[johtie]

Hello.
This is a new question/discusstion but it fits to the original title quite well.

I used A2plus to assembly some Parts..
I can see 2 different behaviours when applying constraints, regarding to the position in the "Tree View" Panel where the constraints appear.
I need to point out, that in order to reconstruct these two behaviours i created the parts for example 1 in the Workbench "Part" and
for example 2 in the "Part Design" Workbench. My FreeCAD File are attached in the .zip File.
I use FreeCAD 0.18.4 on Ubuntu 20.04 LTS.

Now to the 2 behaviours.

1. In my opinion the "right" way.
Both constraints appear under the parts they belong to.

1.png (17.98 KiB) Viewed 4273 times

Another Example on this at youtube: https://www.youtube.com/watch?v=mnkecA9S7kc&t=533s
At 4:25 the first constraint is added, and both appear correctly in the tree view.

2. In my opinion the "wrong" way.
One constraint appears under one of the parts and the second one appears in the top branch of the tree.

2.png (22.08 KiB) Viewed 4273 times

Atnother Example of this at youtube: https://www.youtube.com/watch?v=gV7jK0c7m40
Look at 3:00.

Is this an issue with the "Part Design" Workbench, or A2plus?

[dan-miel]

Is this an issue with the "Part Design" Workbench, or A2plus?

I'm using:
Windows 10
FreeCad 19
Hi Johtie.
When I opened your zipped assembly files both trees looked OK on my machine. Sometimes the sorting of the constraints get a little confused, this can usually be fixed by pressing the “Repair Treeview” button. The icon is shown below. Give this a try.
Dan

[johtie]

Hello.

Thank you for your reply and help.
I can also confirm that the treeview fixes itself when one reopens the file. Should have tried that as well...

Will use the "Repair Treeview" button in the future. =)

BR.