Constraints in a assembly

[PAndrade]

I'm having a real difficult time trying to constrain a part(CNC Y Axis Support Block) to another part(CNC Y Axis L Bracket for Bearing Blocks) within an assembly(CNC Frame Assembly).

If you open the CNC Frame assembly you'll see four L brackets on each corner of the CNC frame and one bracket contains a axis screw support block.

What I'm trying to do is fully constrain the axis screw support block to the support bracket but when I do no matter what I try I get "constraint over defined".
Not sure how to correct this.

I have attached the assembly and parts, not sure if only the assembly would be needed but I sent everything.....
Hopefully this will make sense as described..

Thank you,
Peter

 

[PAndrade]

I should also mention i'm using AlibreAtom 3D..

 

[DavidJ]

Base is missing.

The most common problem users run into is that (unlike in real life), the constraint manager gets upset if you repeat the same constraint. If you can travel a circuit around constrained parts and return to the start point, you are in danger of 'making the snake bite its tail'. To avoid the over constrained message, you need to make at least one constraint around the loop less restrictive - that might involve constraining just an edge rather than a face, or using a 'free offset' just to set orientation, rather than specify a co-incident. There are other variations.

This can be quite tricky to get your head around, it's all to do with the idea that mathematically (and if all our parts were infinitely stiff) when joining 4 straight pieces to make a rectangular frame, you'd only need to fix joints at 3 corners - the 4th corner joint is mathematically redundant and is not needed. In the real world, of course we also fix the 4th corner.

 

[PAndrade]

Thanks David, I'll give this some thought and see what I come up with. I'm not sure what you mean when you say "use a free offset".

 

[DavidJ]

 

[PAndrade]

Well, I got it fully constrained but not sure if it was the most efficient way. I used the offset to nudge the part info position but I feel there is a better way.
Not sure what you are trying to tell me in your post....

Thanks David.

 

[HaroldL]

When uploading an assembly you should provide it as a Package file that will include all the parts of the assembly. It can be created from the File menu:



OR the GEM menu:

 

[PAndrade]

Sorry about that and thanks for letting me know

Peter