Sketcher tutorial

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chrisb
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Re: Sketcher tutorial

Postby chrisb » Thu Jan 03, 2019 1:28 am

I have no idea what's going on, I haven't ever seen this error message. Abdullah, can you help?
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Hannu
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Re: Sketcher tutorial

Postby Hannu » Thu Jan 03, 2019 5:30 pm

FWIW: "Works for me"...

I'd interpret the error message as "one of the points lacks connection with a line segment", which I cannot verify - I see no extra / loose points either.


OS: Ubuntu 16.04.5 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15536 (Git)
Build type: Release
Branch: master
Hash: 98ebeaa198df945ba666c15912c6caf95920f0ef
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)
/Hannu
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sat Jan 05, 2019 12:19 pm

jpg87 wrote:
Tue Nov 27, 2018 12:49 pm
...
I have made some more changes following suggestions from the forum. Thanks to paullee and GlouGlou
paullee wrote:
Tue Jan 01, 2019 3:42 am
And for me need more time to understanding Exercise 32 and 33 :) ... seem a Point-on-Object Constraint should be in 2nd (right hand side) diagram of Exercise 33?
They are supposed to be connected with a coincidence constraint. To make things clearer I changed the text of

Exercise 33 old: Create a sketch with two arcs and let them cross at an angle of 60°.
Exercise 33 new: Create a sketch with two arcs which are connected with a coincidence constraint. Let the arcs cross at an angle of 60°.

Furthermore I changed section 30 Lock constraint
Tabular of Lock constraint old: Number of DOF consumed: 2
Tabular of Lock constraint new: Number of DOF consumed: 2 per point

The same change has to be performed in the overview table at the end of the document

First sentence of Lock constraint old: The lock constraint creates a horizontal and a vertical distance constraint which sums up to 2 DOF.
First sentence of Lock constraint new: The lock constraint creates a horizontal and a vertical distance constraint for each point involved which sums up to 2 DOF per point.

I followed the suggestions of GlouGlou and made some minor changes plus a more substantial change to the last subparagraph, see https://forum.freecadweb.org/viewtopic. ... 48#p278148.

The document is to be found in the same place as before: https://owncloud.gwdg.de/index.php/s/HS ... I/download
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Jan 06, 2019 1:44 am

The description of sketch creation became rather complicated:
• If you don’t have a body in your document, a new body is created, activated, and a new sketch is created inside the body.
• If an existing sketch is selected, you enter sketcher’s edit mode for this sketch.
• If nothing is selected and you have exactly one body in your document, the body is activated and a new sketch is created inside the body.
• If nothing is selected and you have more than one body and one of them is activated, a new sketch is created inside the active body.
• If nothing is selected and you have more than one body and none of the bodies is activated, you are asked to activate one of the bodies.
• If a face from the activated body is selected—or if you have only one body—a new sketch is created and attached to that face.
• If a face from outside the activated body is selected—or if you have only one body—a question is raised how to link the face. If you have only one body it is activated and handled as such.
-– The option ”Make independent copy” creates an unlinked ShapeBinder to which the sketch is attached.
–- The option ”Make independent copy” creates a linked ShapeBinder to which the sketch is attached. If you change the other object the ShapeBinder will follow.
–- The option ”Create crossreference” creates a forbidden link (message: Links go out of the allowed scope). I do not recommend to use this option.
I wonder if I should keep this simpler by making it more general, such as
- Edit if an existing sketch is selected
- create a sketch if the target body can be determined, i.e. there is only one body in the sketch or a body is activated
- attach a new sketch if a face was selected inside the current body
- create a reference if a face was selected outside the current body

What do you think?
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jpg87 wrote:...
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jpg87
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Re: Sketcher tutorial

Postby jpg87 » Sun Jan 06, 2019 10:15 am

chrisb wrote:
Sun Jan 06, 2019 1:44 am
I wonder if I should keep this simpler by making it more general, such as
- Edit if an existing sketch is selected
- create a sketch if the target body can be determined, i.e. there is only one body in the sketch or a body is activated
- attach a new sketch if a face was selected inside the current body
- create a reference if a face was selected outside the current body
Of course, this summarizes the possible situations for someone who stands back; but I think for beginners, the detail of the behaviors is more understandable.
My website : http://help-freecad-jpg87.fr updated 2018/10/17
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Jan 06, 2019 10:54 am

jpg87 wrote:
Sun Jan 06, 2019 10:15 am
but I think for beginners, the detail of the behaviors is more understandable.
Thanks for the input. That means less work - for both of us :D . So I only have to fix the german translation.
paullee
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Re: Sketcher tutorial

Postby paullee » Sun Jan 06, 2019 3:15 pm

chrisb wrote:
Sat Jan 05, 2019 12:19 pm
jpg87 wrote:
Tue Nov 27, 2018 12:49 pm
...
I have made some more changes following suggestions from the forum. Thanks to paullee and GlouGlou
paullee wrote:
Tue Jan 01, 2019 3:42 am
And for me need more time to understanding Exercise 32 and 33 :) ... seem a Point-on-Object Constraint should be in 2nd (right hand side) diagram of Exercise 33?
They are supposed to be connected with a coincidence constraint. To make things clearer I changed the text of
ar of Lock constraint new:[/b] Number of DOF consumed: 2 per point
Thanks, but I am not sure I follow, see screenshots and file attached:-

Left Hand Side 2 Arcs
- I select 1 Arc, 1 point, another Arc
- Apply an Angle Constraints (30 degree)
- Get a point-on-object constraint added (instead of coincidence)

Righ Hand Side 2 Arcs
- I select 1 Arch, another Arc the, lastly 1 point
- Apply an Angle Constraints (30 degree)
- Get a point-on-object constraint added (instead of coincidence)

FreeCAD_0.18.15287.glibc2.17-x86_64.AppImage on Fedora 27
Attachments
Test_ Sketch Ange Constraint_ Arc Point Arc.fcstd
(3.71 KiB) Downloaded 17 times
Screenshot from 2019-01-06 23-00-49.png
Screenshot from 2019-01-06 23-00-49.png (203.68 KiB) Viewed 576 times
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Jan 06, 2019 4:14 pm

Am I right that you are confused by the automatically created point-on-object constraint?
paullee
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Re: Sketcher tutorial

Postby paullee » Sun Jan 06, 2019 4:55 pm

hmm...

"Arc-Arc mode. Similarly you can combine two arcs and a point or an arc, a line, and a
point. This means that Line-Point-Line mode can be viewed as a special form of this
more general mode"

So Exercise 33 and the diagram is not illustrating the above scenario right? - I thought it is.
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Jan 06, 2019 10:22 pm

I have to thank you for reading with such high precision. It's beginning to dawn what you mean: The example does not show unconnected points.

Perhaps it is better to call the last mode Arc-Point-Arc mode and mention that there is no Arc-Arc mode without an additional point. Since it is more frequent that an angle is defined on arcs with connected endpoints I still think that the example is sensible.