Day #3: Antiparallel error when Sweeping a Paperclip in Fusion 360

Issue: 

Day #3 Paper Clip Tutorial: You're trying to Sweep the paper clip in Fusion 360 and receive the following Error: " The start direction of a path segment is antiparallel to the end direction of the previous path segment."

The start direction of a path segment is antiparallel to the end direction of the previous path segment in Fusion 360

Solution: 

The 'Antiparallel' error is caused by Sketch Fillets converging, causing them to be misaligned. (This is a 'bug' with Fusion 360 fillets, which is why it will work sometimes).

1
Hit 'Cancel' in the Sweep dialog to close it. Edit the first sketch by double-clicking on it in the parametric timeline

2
Delete one of the Sketch Fillets. Select the sketch curvature > Right-click > Delete. delete one sketch fillet in Fusion 360
3
Use the Extend feature (Modify > Extend) to extend the Sketch Arc to the other side. You may need to use Extend twice. Extend will reconnect the curvature without the use of two sketch fillets, avoiding the antiparallel error. Extend the sketch curvature in Fusion 360
4
Repeat this process (steps 2-3) for all 3 rounded ends of the paper clip.

5
Activate the Sweep command and finish the paper clip.

Note
: 'Chain Selection' should be checked in the Sweep dialog. This ensures all touching sketch profiles are used for the Sweep path.


Alternate Solutions:

  1. Revert (select Undo) the sketch and apply the sketch fillets one at a time.
  2. Use the 3-point arc command instead of sketch fillets.


Demo File - Paper Clip with Antiparallel Issue

https://a360.co/3bn4CfS


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