Newbie having trouble with sketcher

[OldBikerPete]

As a response to a problem 'Exporting a simple shape doesn't work' I submitted in 'Open Discussion', chrisb suggested a better way of working using sketch. Attached is an example from crisb of a new draw of the problematical object. Then my sketch attempt.
I have drawn a sketch guided by this tutorial 'https://wiki.freecadweb.org/Basic_Sketcher_Tutorial' on using sketcher in the FreeCAD wiki.
My problem is that, having used the editor to draw the sketch I think I need, it disappears off the 3D window when I exit the sketch editor and when I select the sketch and try to use revolver, I get a complaint that the sketch is empty.

[drmacro]

this implies the lines you've drawn in the sketch are all blue and are construction lines which are ignored by any feature creation tool like Pad, Pocket, Revolve, etc.

Have a look at the wiki: https://wiki.freecadweb.org/Sketcher_ToggleConstruction


It also wouldn't hurt to have read through the first pdf in the Learning FreeCAD link in my signature below.

[edwilliams16]

In addition to all your lines being construction lines, there are a lot of places where the lines appear to connect up, but don't. You need to use coincidence or tangential constraints. Once you can drag on your sketch without it coming apart, add the required dimensions. Then you can do a revolution to construct your adapter.

[chrisb]

Don't adorn me with borrowed plumes: I commented your post, but it was Shalmeneser who did the file.

[OldBikerPete]

Well, in that case many thanks to Shalmeneser.

[OldBikerPete]

In addition to all your lines being construction lines, there are a lot of places where the lines appear to connect up, but don't. You need to use coincidence or tangential constraints. Once you can drag on your sketch without it coming apart, add the required dimensions. Then you can do a revolution to construct your adapter.

I have since noticed that lack of connection but haven't yet figured out how to get line segments to join up. At what point do I add that constraint? Errmmmmm. How do I add a constraint?

Peter. Who has devoted at least 20 hours to this problem so far with zero noticeable progress.

[chrisb]

I have since noticed that lack of connection but haven't yet figured out how to get line segments to join up. At what point do I add that constraint? Errmmmmm. How do I add a constraint?

Have a look at the (English) document linked in my signature.

If you have it quite properly aligned, but not connected via constraints, then the Sketcher ValidateSketch tool can create an initial set of coincidence constraints by fixing the unconnected points.

[drmacro]

...Errmmmmm. How do I add a constraint?

Peter. Who has devoted at least 20 hours to this problem so far with zero noticeable progress.

Did you spend 15 minutes reading the first pdf in the link in my signature as I mentioned previously?

If it did not answer this question, I would like to know how to improve it...

[Zolko]

Did you spend 15 minutes reading the first pdf in the link in my signature as I mentioned previously?

If it did not answer this question, I would like to know how to improve it...

1) the link in your signature doesn't actually lead to a PDF, it leads to your GitHub account. The link to the document is:

https://github.com/macdroid53/LearningF ... reeCAD.pdf
or even better
https://github.com/macdroid53/LearningF ... reeCAD.pdf

2) the documents spends a lot of time about what is not ("this document is not for the seasoned "), and not so much about "So where do you start to design a given idea ? " Why begin to talk about the Draft WB and tell to skip it ? It's confusing. Also, this shouldn't be a course on 3D modeling ("Designing things with a CAD program entails a variety of skills " !!!), but a beginner's guide to this tool (FreeCAD) for experienced 3D designers. You could add to your intended audience introduction that some per-requisits about 3D design is a must-have.

3) I'd suggest as a a first lesson: import STEP files from Internet, and learn how to visualize them, rotate them, zoom, save, re-open, change colors, transparency, select objects, faces, edges .... Get used to the interface, tree-view, property-view, play with the toolbars ... Learn to use FreeCAD as a reader before using it as an editor.

4) as second lesson, create a sketch and draw on it, make circles, squares, lines, learn the constraints ... (switch to sketcher WB, create sketch, assign to XY plane, draw). No need to mention PartDesign or Part or Draft WB for this

5) only after 3) and 4) would I go to actually making a part

[GeneFC]

5) only after 3) and 4) would I go to actually making a part

I disagree. That might work in a classroom with a knowledgeable instructor and a lesson plan, but for an individual learner it would be a disaster. How would anyone know what to "practice"?

Far better is to start with a simple tutorial such as those in the wiki.

https://wiki.freecadweb.org/Tutorials

Pick one that matches one's modeling interest and work through it. All of the necessary elements of working with the tree, sketching, toolbars, etc. will be covered in a basic manner without excessive detail. Build from that start once the basics are introduced.

Some people like videos (I don't), but the huge quantity and the mixed quality can be problematic.

Gene