Can autocad draw imposible geometry in an isometric?

I am working on patterns for what look like simple parts. But there are large chamfers on the part that are cut to parallel planes vertically but there is an angle on how how much is chamfered on the top face. So the angle on the chamfer is a rolling bevel with angles different on each end of the chamfer and changing continuously from one end to the other. I was able to model that without too much trouble but there is then a chamfer off the side of the part intersecting with the first chamfer which also has to be a rolling bevel.

The drawing in both plan views and isometric show the line between the 2 chamfers as being straight but any way I model it I get curved lines where the 2 rolling bevels meet. I asked for a model and was sent a DWG not a 3d model so maybe there is no 3d model. Maybe I am just modeling it incorrectly but I am wondering if they could have drawn impossible geometry? Unfortunately my customer is the foundry not the final customer so communication is slow and through an intermediary.

Here is the model simplified so I am not sharing proprietary details showing showing the chamfer that is an issue in the one corner. The curved line is supposed to be straight but is curved because of the rolling bevel.

The intersection of 2 planes is a straight line - impossible geometry - however, a continuosly changing angle is also known as a curve - so curved intersection would be appropriate

It is possible that being just a 2d drawing it is not 100% accurate. Not sure about Acad, but with some softwares you can have a simplified 2d wireframe that will not be a 1-1 'translation' from 3d model to 2d wireframe.

I have managed to get the line shown straight while viewed from the top by cutting a triangle out of the part inserting a surface and then extruding back to the surface. However the line is still a slight curve while viewed from the side. I think it will have to do as what the drawing shows is not really geometrically possible.

Can't really help without knowing what the drawing looks like.

You can draw anything in Autocad. Or any other software, really. Just like with a pencil. Doesn't mean it's doable. So the answer is 'maybe' I guess.

Mike1974 said:

It is possible that being just a 2d drawing it is not 100% accurate. Not sure about Acad, but with some softwares you can have a simplified 2d wireframe that will not be a 1-1 'translation' from 3d model to 2d wireframe.

Click to expand...

acad calculates all points of the intersection...two curved surfaces always make a curved line



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;-D