Sanity check please

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Posts: 235
Joined: Tue Nov 20, 2018 1:00 am
Location: Ovando, MT, USA

Sanity check please

Postby garya » Tue Oct 15, 2019 2:46 am

I'm having trouble understanding why a multitransform or linear pattern complains about "transformed shape does not intersect support"

Attached is a .FCStd file exhibiting the error. To see it:
Double click TipDepositPlatform_Base to make it the active body.
Activate PartDesign WB
Click on ProtoSupport to select it.
Click on "Create a Linear Pattern Feature"
Change the length to 107

The error (scroll up to top of Task dialog to see it) says "One transformed shape does not intersect support", and the second X turns red indicating the error.

What is the "support" it is not intersecting? It clearly intersects the main body. If you change the length to 106 it is fine. If you make the ProtoSupport extrusion taller the error still occurs, so it is not an issue with the height being the same as the cutout it is filling. If you change the number of occurrences to 3, 4, 5, 6, 7, 8, 9 it is fine, but it complains again at 10.

Is this possibly related to the fact that the sketch creating the 'X' contains crossing lines?

OS: FreeBSD 11.2-RELEASE-p4
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Build type: Release
Python version: 3.6.9
Qt version: 5.12.2
Coin version: 3.1.3
OCC version: 7.3.0
Locale: C/Default (C)
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Re: Sanity check please

Postby vocx » Tue Oct 15, 2019 4:45 am

garya wrote:
Tue Oct 15, 2019 2:46 am
...linear pattern complains about "transformed shape does not intersect support"
Typically the OCCT geometric kernel doesn't like self-intersecting sketches, which you seem to have in the X shape.

Although it may work at first, as it seems it does with your "ProtoSupport" Pad, subsequent boolean operations may fail with strange messages, as you seem to be getting with the linear pattern. Use the Part CheckGeometry tool to inspect your solids for problems like self-intersections and boolean operations on co-planar faces. Best results are obtained when the boolean operations (BOP) check returns clean.

Left good, right bad.
Self_intersection.png (7.74 KiB) Viewed 351 times
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Re: Sanity check please

Postby pl7i92LCNC » Tue Oct 15, 2019 5:39 pm

its a straight lerning curve as on every CAD gods its own function to be used
get ahead of the basics and you are fine on doing your konstruction with the opensource
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Re: Sanity check please

Postby garya » Wed Oct 16, 2019 3:50 am

Thanks for the explanation and pointer. I wondered about the intersection but thought it was ok since the first X came out ok.