Boolean Failures #71009

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NoOne · 2019-10-22T01:38:53+02:00

NoOne commented

2019-10-22 01:38:53 +02:00

System Information
Operating system: Windows 7 Professional 64 bit with SP1
Graphics card: Intel I7 Integrated

Blender Version
Broken: (example: 2.80, edbf15d3c0, master, 2018-11-28, as found on the splash screen)
Worked: (optional)

Short description of error
Boolean Difference Fails 39 out of 40 times. Cannot reproduce the 1 working case.

{F7845292}Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
Select internal gear then modify with Cylinder Boolean difference to trim gear teeth. Blender either performs Union or else does something even more bizarre.

**System Information** Operating system: Windows 7 Professional 64 bit with SP1 Graphics card: Intel I7 Integrated **Blender Version** Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen) Worked: (optional) **Short description of error** Boolean Difference Fails 39 out of 40 times. Cannot reproduce the 1 working case. {[F7845292](https://archive.blender.org/developer/F7845292/Test.blend)}**Exact steps for others to reproduce the error** Based on the default startup or an attached .blend file (as simple as possible). Select internal gear then modify with Cylinder Boolean difference to trim gear teeth. Blender either performs Union or else does something even more bizarre.

NoOne commented

2019-10-22 01:38:53 +02:00

Added subscriber: @Zet0p4n

Roger B commented

2019-10-22 02:58:44 +02:00

Added subscriber: @rboxman

Roger B commented

2019-10-22 02:58:44 +02:00

You're hitting 2 known issues as part of: #67744 (some mentioned as part of #47030 too)

You're using a non-manifold mesh. Your 'InternalGear' object is not solid.
You're using co-planar geometry. Your cylinder top is aligned perfectly with the top of the 'InternalGear' object.

Workaround: Close off your InternalGear object and shift the cylinder up. Works for me here after that:

some teeth:

no teeth:

You're hitting 2 known issues as part of: #67744 (some mentioned as part of #47030 too) 1. You're using a non-manifold mesh. Your 'InternalGear' object is not solid. 2. You're using co-planar geometry. Your cylinder top is aligned perfectly with the top of the 'InternalGear' object. Workaround: Close off your InternalGear object and shift the cylinder up. Works for me here after that: some teeth: ![some_teeth.png](https://archive.blender.org/developer/F7845429/some_teeth.png) no teeth: ![no-teeth.png](https://archive.blender.org/developer/F7845431/no-teeth.png)

NoOne commented

2019-10-22 03:21:03 +02:00

"Close off your InternalGear object and shift the cylinder up."

I am new to Blender and I used a 3rd party plug in which accurately generates involute gears. As a result of the former I have no idea of how to close off the gear, could you provide a pointer to how that would be accomplished? Curiously, after a large number of tries it did work once but my cylinder radius was slightly incorrect and I haven't been able to reproduce that single working case.

Thank you for your surprisingly (to me) very quick response.

"Close off your InternalGear object and shift the cylinder up." I am new to Blender and I used a 3rd party plug in which accurately generates involute gears. As a result of the former I have no idea of how to close off the gear, could you provide a pointer to how that would be accomplished? Curiously, after a large number of tries it did work once but my cylinder radius was slightly incorrect and I haven't been able to reproduce that single working case. Thank you for your surprisingly (to me) very quick response.

Stanislav Blinov commented

2019-10-22 03:54:09 +02:00

Added subscriber: @Stan_Pancakes

Stanislav Blinov commented

2019-10-22 03:54:09 +02:00

Simply closing off may not be 100% sufficient here, as the modifier might then generate inverted faces. Booleans in Blender (at least for the time being) like simple geometry, and despise open geometry and tiny faces, overlapping faces, etc. Attaching a video on how to fix your mesh for a clean Boolean operation. For clarity on what's going on, I tried not to use any hotkeys, except Shift+B (zoom to rectangle), and Ctrl+R to insert the five cuts back. fix_gears_for_boolean.mkv
Fixing the result that @rboxman likely gets is actually even faster, but again, the Boolean may not even work in a similar situation with a slightly different mesh, so hopefully the full procedure gives you some ideas on how to overcome such problems.

Simply closing off may not be 100% sufficient here, as the modifier might then generate inverted faces. Booleans in Blender (at least for the time being) like simple geometry, and despise open geometry and tiny faces, overlapping faces, etc. Attaching a video on how to fix your mesh for a clean Boolean operation. For clarity on what's going on, I tried not to use any hotkeys, except Shift+B (zoom to rectangle), and Ctrl+R to insert the five cuts back. [fix_gears_for_boolean.mkv](https://archive.blender.org/developer/F7845534/fix_gears_for_boolean.mkv) Fixing the result that @rboxman likely gets is actually even faster, but again, the Boolean may not even work in a similar situation with a slightly different mesh, so hopefully the full procedure gives you some ideas on how to overcome such problems.

NoOne commented

2019-10-22 13:15:33 +02:00

Thank you Stanislav! However what you did in the video is well past my current knowledge of how to use blender so it's going to take me some time to understand how to perform all of the steps that you used. Also note that the gear geometry needs to be kept as exact as possible since this is an attempt to determine if a specific kind of gearbox could actually function. In other words I need to be able to detect if the internal gear teeth would interfere with some additional pinion and internal gears that are not yet shown in my failed example.

Stanislav Blinov commented

2019-10-22 14:19:12 +02:00

Changed status from 'Open' to: 'Archived'

Stanislav Blinov closed this issue

2019-10-22 14:19:12 +02:00

Stanislav Blinov self-assigned this 2019-10-22 14:19:12 +02:00

Stanislav Blinov commented

2019-10-22 14:19:12 +02:00

You're welcome. Like I said, I tried to show all the steps and tools in the video, so you could see how they work and have keywords to search for in the documentation for additional information.

It's best to try support questions such as this on the community resources , for example BlenderArtists, before reporting a bug. While you're learning, you're likely to encounter more obstacles that aren't necessarily bugs, and there are lots of experienced users out there who should be able to help.

You're welcome. Like I said, I tried to show all the steps and tools in the video, so you could see how they work and have keywords to search for in the [documentation ](https://docs.blender.org/manual/en/latest/) for additional information. It's best to try support questions such as this on the [community resources ](https://www.blender.org/community/), for example BlenderArtists, before reporting a bug. While you're learning, you're likely to encounter more obstacles that aren't necessarily bugs, and there are lots of experienced users out there who should be able to help.

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Boolean Failures #71009