[SOLVED] Bug #2266: error cutting helix from cylinder (Testers needed)

[Kunda1]

issue #2266: error cutting helix from cylinder
needs to be tested. Please report results in this thread.

[NormandC]

This is a typical error with Booleans on threads. There are tens of topics about this on the forum, and the reported should have opened a forum topic first rather than polluting the tracker with yet another report about this well-known issue.

TWe've always been told it's an OCC issue, I'm surprised it works in Salome. The fix is simple, rotate Sketch001 on the Z axis by a few degrees (actually it can be as small as 0.005 degrees) to make sure the seam edge of Pad's inner cylindrical surface is not aligned with the Sweep starting end.

I would close this as invalid. Unless developers tell us it's been a precision issue all along?

[Kunda1]

This is a typical error with Booleans on threads. There are tens of topics about this on the forum, and the reported should have opened a forum topic first rather than polluting the tracker with yet another report about this well-known issue.

TWe've always been told it's an OCC issue, I'm surprised it works in Salome. The fix is simple, rotate Sketch001 on the Z axis by a few degrees (actually it can be as small as 0.005 degrees) to make sure the seam edge of Pad's inner cylindrical surface is not aligned with the Sweep starting end.

I would close this as invalid. Unless developers tell us it's been a precision issue all along?

@NormandC with these older bugs do you mind notating the ticket directly? It helps get them visible on the tracker and helps me from a monitoring perspective because I see that there is progress occurring, Thanks! Oh and thanks for your response as well!

[NormandC]

@NormandC with these older bugs do you mind notating the ticket directly?

Done.

[user1234]

Hello!

Because i never had any problem with helixes and sweeps, i tested this on my machnine and .... no errors and problems, when i rebild it new 1:1.

Here with geometry check:

0001.png (191.56 KiB) Viewed 2689 times

Modeltree:

0002.png (180.68 KiB) Viewed 2689 times

Overlay with original from BugReport:

0003.png (187.3 KiB) Viewed 2689 times

Here the overlay with the original, were the original has an error:

0004.png (223.07 KiB) Viewed 2689 times

Here the file:

JY_corr._with_0.17.9797_OCCT7.1.0.fcstd

(203.54 KiB) Downloaded 59 times

Here my machine:

Code: Select all

OS: Debian GNU/Linux 8.7 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.9797 (Git)
Build type: Unknown
Branch: master
Hash: 9a6191f5726d6588c650ffab4c65fdfb835bc2da
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.1.0

Maybe it is/was an OCC(T)/OCE problem, but I don't know. I can only code small snippets and the code of FreeCAD is much to high for me.

I hope this was a helpful, btw. awesome work this FreeCAD, really ...... i love this.

[NormandC]

Hi user1234,

That's good to know! One more thing to look forward to with OCC 7+.

Because i never had any problem with helixes and sweeps

Even with older versions of OCC?

[user1234]

Even with older versions of OCC?

I made not many helixes but i never had a problem with it. But i started the sweeps never in rectangular Plane from the Placement, because i know that other CAD programms have also problems with that. I am also make no sweeps with inner intersections. And when i make bool operation then i make no tangentys surfaces, intersect always full, .....

But as i said, i used it rarely.

Greetings
user1234

[7eggert]

I tried the 0.17 git 86d9191023e28d67307fdec4e09ad8cb69335c6f version, compiled on Debian Jessie. I tried to try.

Loading a file from 0.16, it's just differently broken. I managed to union a not-self-intersecting helix-sweep and the parts with the central cylinder (creating a screw), but then intersecting that with the desired length didn't work.

(While testing with a new file, I didn't manage to create a new helix sweep. Create sketch, just draw a circle outside origin, create helix; Sweep; move sketch to the right, select helix, "OK": "Links go out the allowed scope" ... which links, which scope? I'm not even sure weather that's a bug, but it stops me from testing.)

[jmaustpc]

I tried the 0.17 git 86d9191023e28d67307fdec4e09ad8cb69335c6f version, compiled on Debian Jessie. I tried to try.

I suspect you have an old version of the CAD kernel that freecad uses, if you posted your version data in the manner explained the Forum Rules link above the Help Forum then we would know.

This bug report and topic is a waste of time, it's just yet another duplication of a well known limitation in OCC, that for now a user can work around, is an OCC issue not FreeCAD, and regardless has been discussed, and resolved as much as possible, many times before.

[7eggert]

So the "copy to clipboard" function copies more than the visible information, and the freecad kernel isn't part of freecad ...

(Skip this, it's for completeness and now useless)

OS: Debian GNU/Linux 8.9 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.12309 (Git)
Build type: Unknown
Branch: master
Hash: 86d9191023e28d67307fdec4e09ad8cb69335c6f
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.7.0
Locale: C/Default (C)

(skip ends)

As to working around the problem: Nope, I gave up after a day of googeling, tilting the sketch and not having touching edges; and compiled the git version. As soon as it's more complicated than just having a standalone part, Freecad foobarfs randomly.

I guess you should close this thread because it's that (OCC?)' lib's fault and put that overly-frequently asked question into the FAQ? Possibly ask for testers with OCC 7 in a new thread? After reading this meager google/forum-search result, I wasted an extra day trying to help fixing this nagging-me bug and not knowing it would be futile. "(Helix) Sweep + boolean/cut/intersection/union/ does not work correctly with FreeCAD and OCC < 7.x, please wait for the next release" (assuming I understood correctly)

HTH, and thanks for FreeCAD