When I plot my model using 3D MODELER, sometimes the whole piping model turns to a big solid cubic.
Why does it happen? and How can I resolve this?

Thanks in advance....

What version and build are you using?

Typically this means your graphics card is too slow or it doesn't have sufficient on-board RAM to handle the model you're plotting.

You can try this to improve performance:
- go to the Configuration Module
- go to the 3D Viewer Settings tab
- scroll down to the "Miscellaneous Options" section.
- for "Optimal Frame Rate", change this value to 1

You'll probably need to delete the .XML file to recover from the "cube".

(This happens because if the response of the graphics card isn't fast enough, the model degrades, in an attempt to maintain performance. However, if things degrade too far ...