I am working on a mixer for a main project through which i used many edge loops and when it was time for the subdivision all lines of the wire frame should be straight but they are some that are not straight. After hours of trying I can not find the issue. can some go in the file and fix and tell me what to do step by step.
Your help is needed dearly.
i viewed the tutorial on YouTube and it did not helped also

You don't have enough edges to support sub-d modelling. You need more edge loops to keep the edges crisp.

Also I don't know what tutorial you are following, but blasting and rebuilding polygons is not the way I would do it. You can get the exact same result using 1 polyextrude node instead.

I have modified your box, I have placed a null called “THIS_IS_WHERE_I_STARTED” Everything I did follows this node.

I also rebuilt the same thing from sctratch in a fresh geo node, and modelled it my way.
If you look at yours, there are edges everywhere. On flat surfaces you can terminate edge loops without needing to worry about the polys not being 4 sided. If you look on mine, I've terminated the edges around the small depression leaving some triangles. That means you can optimize your model instead of it being geometrically heavy right across the mesh. Note how on flat surfaces how these tri's dont make any difference to the smoothing? If it was a curved surface then they would be a pain to have on the model.

Cheers

Thank you for explaining what I have to do. Your explanation helped me understand where I went wrong
Thanks again