In this example, the model’s absolute tolerance is 0.01 and the angle tolerance is 0.1°. The red NURBS curve is (0.0000°) tangent with the line on the left.
After using _Connect to close the gap between the NURBS curve and the line on the right, the former is converted to an arc, deviating about 0.01 mm (full model tolerance) and 3° (tangent vector) at the left end point.
Not only should there be a warning when the output deviates from the input as in this example, there should also be an option to disable simplification.
The deviation is 0.00982582, which is less than the document tolerance. It doesn’t look like the angle tolerance is used in this case. Apart from that, your image shows a different file than the one that you posted, and in that file, the gap between the two curves is 0.0439, which is well below the recommended one magnitude difference between file tolerance and model features.
At any rate, I’ve put that file on the list of the developer to take a closer look.
→ RH-85447 Connect: Converts NURBS Curve to Arc
-wim
In this case, I needed to connect the curves then use them as rails for _Pipe, so closing the gaps, maintaining tangency, and reducing distance tolerance stack up are all important. The latter comes into play when the curves have already been projected onto surfaces, thus using up some of the model tolerance.
