Cut: resulting shape is invalid

[Raph82]

Hello,

I can't remove a cube from an array in the attached file. I get a "resulting shape is invalid" error.
The file attached is a simplified version of what I'm working on, saved with FreeCAD 0.17.

A first cut "020 Chevrons Cut" was done by removing "110 Vue en coupe" from "020 Chevrons Array".
Now I want to remove "110 Vue en coupe" from "045 Isolant Array".
I've done a couple of cuts from the same cube and this is the only one which does not work.

From previous topics in the forum, I ruled out the following leads:
- not a coplanar issue
- a forced recompute had no effect
- rotate is not really applicable here and does not work anyway
- bug from an old version

I usually use this version of FreeCAD:
OS: Linux Mint 18.1 Serena
Word size of OS: 32-bit
Word size of FreeCAD: 32-bit
Version: 0.16.6710 (Git)
Build type: None
Branch: releases/FreeCAD-0-16
Hash: f8eca0f9311f07c125dd6742a607724c1fa0b77c
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

I tried with this one from -daily and got the same "resulting shape is invalid" error:
OS: Linux Mint 18.1 Serena
Word size of OS: 32-bit
Word size of FreeCAD: 32-bit
Version: 0.17.11284 (Git)
Build type: None
Branch: master
Hash: 1854d3de696cc51c769d82f19d7d2fb1e0ce787e
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.1.0

What am I doing wrong?
If nothing comes up I'd submit a bug report.

Thanks for your help!

[tanderson69]

turn on the bop algo check and run check geometry on your array. Bad condition.

arraySelfIntersection.png (148.15 KiB) Viewed 2654 times

[GeneFC]

The second array "X" spacing is exactly the same as the cube "X" dimension, 575 mm. When I added a tiny amount to the array spacing the cut worked without error.

I believe it *is* a coplanar issue of some sort.

Gene

[Raph82]

Thanks to you tanderson69 and GeneFC, I now understand what happens. I'll change my array, even if I think it's supposed to work as is
For future reference, there is a Wiki page explaining in more details how to turn on BOPAlgo check and how to check a part geometry.

[bejant]

I can't remove a cube from an array in the attached file.

The second array "X" spacing is exactly the same as the cube "X" dimension, 575 mm.

And so if we toggle the Property Fuse (in Combo View > Data Tab, lower left corner of the FreeCAD window by default) of "045 Isolant Array" from False to True, Cut001 works and the model is good.