Sketcher tutorial

A place to share learning material: written tutorials, videos, etc.
chrisb
Posts: 15802
Joined: Tue Mar 17, 2015 9:14 am

Re: Sketcher tutorial

Postby chrisb » Fri Jan 18, 2019 7:43 pm

Thank you very much.
B-splines are at the bottom of the left table, conics have to be addded.
dxp.dev
Posts: 47
Joined: Tue Dec 11, 2018 12:57 pm

Re: Sketcher tutorial

Postby dxp.dev » Mon Jan 21, 2019 5:08 pm

Could we see that tutorial on the Tutorial page of the FC site (https://www.freecadweb.org/wiki/Tutorials/en) ?
chrisb
Posts: 15802
Joined: Tue Mar 17, 2015 9:14 am

Re: Sketcher tutorial

Postby chrisb » Mon Jan 21, 2019 5:50 pm

It's not there because it doesn't really fit the wiki tutorials format yet.
chrisb
Posts: 15802
Joined: Tue Mar 17, 2015 9:14 am

Re: Sketcher tutorial

Postby chrisb » Fri Feb 22, 2019 4:39 pm

In the tutorial I write about the grid in Sketcher:
The grid For now open the ”Edit controls” and uncheck the ”Show grid” checkbox. The grid is only helping to place geometric elements. If you have ”Grid snap” enabled it suggests that snapped points have their positions already defined, which in fact they have not. So I prefer to have it switched off to avoid confusion.
In the comments on the document opeBrain writes about the second sentence
openBrain wrote: This sentence is quite unclear to me.
I am unsure how to express the fact, that unlike other 2D programs the snapping does not define a point to stay at its snapping point, no constraints are created.

I hope for some clarifying words from the community.
openBrain
Posts: 1135
Joined: Fri Nov 09, 2018 5:38 pm

Re: Sketcher tutorial

Postby openBrain » Fri Feb 22, 2019 7:18 pm

chrisb wrote:
Fri Feb 22, 2019 4:39 pm
I am unsure how to express the fact, that unlike other 2D programs the snapping does not define a point to stay at its snapping point, no constraints are created.
Hi chrisb,
As I'm responsible for trouble, and now I clearly understand what you expect, please let me have a try. :)
I would like this sentence :

Code: Select all

If you have ”Grid snap” enabled it suggests that snapped points have their positions already defined, which in fact they have not.
to be something like

Code: Select all

If you have "Grid snap" enabled, you may think that points will be permanently locked on the grid-points where they was dropped on, while actually they won't.
HTH
GeneFC
Posts: 1007
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Sketcher tutorial

Postby GeneFC » Fri Feb 22, 2019 8:25 pm

OB,

I think you are missing the point. It does not matter where the points actually exist. If one uses grid snap the two points will be in exactly the same place.

The important point is that those two points are not linked as "coincident" unless that constraint is specifically applied.

Location and coincidence are two different concepts in the Sketcher.

Gene
openBrain
Posts: 1135
Joined: Fri Nov 09, 2018 5:38 pm

Re: Sketcher tutorial

Postby openBrain » Fri Feb 22, 2019 8:39 pm

GeneFC wrote:
Fri Feb 22, 2019 8:25 pm
I think you are missing the point.
ATM I don't think so. :) chrisb has worded it as "the snapping does not define a point to stay at its snapping point", which I tried to reword the way I would have like to read it. ;)
But I may be wrong. In this case, I'm pretty sure chrisb will complain about my reply. :lol:
GeneFC
Posts: 1007
Joined: Sat Mar 19, 2016 3:36 pm
Location: Punta Gorda, FL

Re: Sketcher tutorial

Postby GeneFC » Fri Feb 22, 2019 10:03 pm

I agree the wording could be cleaned up a bit.

However, the concept that causes confusion on the forum, again and again, is that somehow overlapping position means there is a connection. I believe in some programs and even other parts of FreeCAD snapping means connection. In sketcher it does not.

In ordinary life, overlap and coincidence are the same thing. In FreeCAD sketcher they are not the same.

Gene
User avatar
bejant
Posts: 5567
Joined: Thu Jul 11, 2013 3:06 pm

Re: Sketcher tutorial

Postby bejant » Sun Feb 24, 2019 4:05 am

chrisb wrote:
Fri Feb 22, 2019 4:39 pm
In the tutorial I write about the grid in Sketcher:
The grid For now open the ”Edit controls” and uncheck the ”Show grid” checkbox. The grid is only helping to place geometric elements. If you have ”Grid snap” enabled it suggests that snapped points have their positions already defined, which in fact they have not. So I prefer to have it switched off to avoid confusion.
(snip)
I hope for some clarifying words from the community.
My suggestion:
The grid. For now open the ”Edit controls” widget and uncheck the ”Show grid” checkbox. Although the grid can be helpful when placing geometric elements, it is important to remember this:
  • Geometric elements placed at grid intersections are never secured to the grid;
  • Separate pieces of geometry that share a point at the same grid snap location are not secured to one another, and they may move apart unexpectedly until a Constraint is applied between those shared points.
If you have ”Grid snap” enabled it might seem that snapped points have their positions already defined by the grid intersection, when in fact they are free to move. So I prefer to have it switched off to avoid confusion.
User avatar
Hannu
Posts: 88
Joined: Fri Sep 11, 2015 4:12 pm
Location: Strängnäs - 1hr drive west from Stockholm, Sweden

Re: Sketcher tutorial

Postby Hannu » Mon Feb 25, 2019 9:01 pm

GeneFC wrote:
Fri Feb 22, 2019 10:03 pm
However, the concept that causes confusion on the forum, again and again, is that somehow overlapping position means there is a connection.
Gene
Part of that might be the fact that coincident constarints do not show up in the sketch, the same way that others do (with a symbol).
/Hannu