Artifact at start and end interface of subtractive sweep

[kishore]

I was creating a worm gear and I'm getting an artifact that I think is the result of some rounding errors. My question is how do I fix it or work around it? I considered sweeping over the same edge (circle) twice to overpass the artifact but I cannot select the same circle to sweep again. I know i can create a second circle sketch and use that as the second edge in the sweep

I am unable to attach the file due to file size of 2.1MB.

WormGear.png (62.37 KiB) Viewed 586 times

OS: KDE neon User Edition 5.21 (KDE/plasma)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.19.1)
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.8
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.4.0
Locale: English/India (en_IN)

[chrisb]

If you followed all the tipps in the Thread for Screw Tutorial and the issue persists, upload the file to a publicly available file service (without the need to register for others).

[Willem]

It is difficult to guess, how did you make this, in Partdesign or in Part workbench. Did you use a Part helix or a Partdesign subtractive helix.
A common mistake is that the sketch is on the same angle as the split of the cylinder. Here an example of how it works

[chrisb]

Thinking about it: it could also be a misaligned sketch. It is best to attach the section with attachment mode FrenetNB without any further rotation.

[kishore]

I have uploaded the file here.

It is difficult to guess, how did you make this, in Partdesign or in Part workbench. Did you use a Part helix or a Partdesign subtractive helix.
A common mistake is that the sketch is on the same angle as the split of the cylinder. Here an example of how it works

It is made in partdesign with subtractive sweep where an internal involute gear is sweeping around a cylinder. The sweep path is a circle that is concentric with the cylinder but since I require the profile to twist along its axis by one tooth angle, a suitable aux path is constructed as a helix.