Datum (Planes, Lines, Points) and holes

[Wegge]

I'm working on creating a filament storage box feed attachment with an aesthetic that's a little more appealing than the typical rectangle with rounded corners. I have hacked a first iteration together. There are some places where I'm unsure whether I missed something:

• I have a datum line going through the origin of the plane, so I have an aimpoint for the protuding cylinder. Getting that placed took a lot of futzing with the attachment mode. If the base shape had been more complex, how would I go about aligning it with a feature on that?
• Getting the datum plane placed was even more frustrating. In the end, I modofied the Z displacement until it "looked right". What I really would have liked was to place it with the datum line as a normal and coinciding with the edge of the two topmost holes.
• Speaking of holes, what am I missing with the center hole (Hole001). It's marked as threaded, so I expected the hole to have an internal thread. Is this option just meant as a shortcut to generate the right size of bore for a given thread?

And the obligatory version informaton.

OS: "Fedora release 28 (Twenty Eight)"
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14957 (Git)
Build type: Unknown
Branch: master
Hash: 22513600ddc11a8d0d392f67225d443b7dc2e5bb
Python version: 2.7.15
Qt version: 4.8.7
Coin version: 3.1.3
OCC version: 6.9.1.oce-0.18
Locale: Danish/Denmark (da_DK)

[chrisb]

I wonder what's going on with this model, but first things first:

• The DatumPoint in the origin is obsolete, you could use the origin itself
• The same holds for the DatumLine: It is the same as the Z axis.
• And again the DatumPlane: It is the same as the XY plane

It is recommended to use DatumGeometry instead of attaching sketches to faces and instead of referencing edges and vertices. But there is no advantage in using DatumGeometry if you can use the principal planes directly.

Now comes the weird part: Starting from the DatumPoint, all DatumGeometry, sketches and features are called "Unnamed" and they all are unconnected. I have no idea how you got there.

OS: macOS High Sierra (10.13)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14955 (Git)
Build type: Release
Branch: (HEAD detached at e66849378)
Hash: e66849378bd03373c1c0d7c754bf78db85e2aff1
Python version: 2.7.15
Qt version: 5.11.2
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: German/Germany (de_DE)

[chrisb]

Same situation on Ubuntu (just updated from the PPA).
OS: Ubuntu 16.04.5 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.14956 (Git)
Build type: Release
Branch: master
Hash: 0e948db5a38bed9b8ac177fb77756161b45489b6
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)

[DeepSOIC]

Now comes the weird part: Starting from the DatumPoint, all DatumGeometry, sketches and features are called "Unnamed" and they all are unconnected. I have no idea how you got there.

Cannot get value from invalid enumeration
Thread size out of range
Cannot get value from invalid enumeration
Thread size out of range
Invalid Document.xml: Thread size out of range
Seems like hole feature is failing to restore from a file. Again (AFAIR, there was a similar problem, reported, then fixed).

[Wegge]

I wonder what's going on with this model, but first things first:

• The DatumPoint in the origin is obsolete, you could use the origin itself
• The same holds for the DatumLine: It is the same as the Z axis.
• And again the DatumPlane: It is the same as the XY plane

Yes, the datum point is redundant. But the line and plane are, at least in my design, tilted 60 degrees from the XY-plane. The attached picture is what it sliced to as STL. Trying to open the file again give me the same gibberish. Revision 2 that was a refinement of the posted file could sort-of open, although I had to delete fillets and the three holes in the lobes.

Three lobe filament box connector plate.png (689.99 KiB) Viewed 1552 times

[eivindkvedalen]

• Speaking of holes, what am I missing with the center hole (Hole001). It's marked as threaded, so I expected the hole to have an internal thread. Is this option just meant as a shortcut to generate the right size of bore for a given thread?

The hole fails to restore from file, also noted by others. Could you please register this in the tracker, and reference this thread? I think your sample file here should be sufficient to fix the bug.

Edit: To answer your question: It does not currently create the actual CAD model of the thread. This is normally not done in any CAD programs. Some use a texture with threads for decorative purposes. Creating the thread model is planned, as it is useful for e.g printing parts with threads. Currently threaded holes are made with a diameter such that they can be threaded with a tool afterwards.

Eivind

[freedman]

We can certainly help you draw that in a more efficient and usable way.

[chrisb]

Could you please register this in the tracker, and reference this thread?

Done: issue #3627. I assigned it to you; left the target version open.

[Wegge]

We can certainly help you draw that in a more efficient and usable way.

Do tell!

[wmayer]

git commit b65faeff771