Newbie - Sketcher multiple line constraints

Post here for help on using FreeCAD's graphical user interface (GUI).
Forum rules
and Helpful information
IMPORTANT: Please click here and read this first, before asking for help

Also, be nice to others! Read the FreeCAD code of conduct!
makerInOregon
Posts: 1
Joined: Fri Feb 07, 2020 12:02 am

Newbie - Sketcher multiple line constraints

Postby makerInOregon » Fri Feb 07, 2020 12:15 am

So total newbie to FreeCAD, though I was a power ProE user 10 years ago when I changed careers.

I am going through the basic part creation tutorial (https://www.freecadweb.org/wiki/Creatin ... PartDesign) and I cannot for the life of me get Sketcher to work how they describe, nor could I find a mention of the issue I am having in the forums

So I follow the directions and a couple of things
No auto constraints are created in the way the tutorial describes
The lines are not linked (even when I start the next line highlight the end point of a previous line yellow)

I've tried a new document, a new sketch, changing the sketch parameters and I keep getting the same behavior.

I was able to manually select both end points and select the "Coincident constraint". Though I can't imagine that is what everyone does all the time. I assume this is a simple newbie kind of issue and your guidance would be appreciated.

OS: Windows 10
FreeCAD Version: 0.18
Revison Number: 4
Word Size: 64-bit
Branch: releases/FreeCAD-0-18
Python: 3.6.6
vocx
Posts: 5049
Joined: Thu Oct 18, 2018 9:18 pm

Re: Newbie - Sketcher multiple line constraints

Postby vocx » Fri Feb 07, 2020 12:38 am

makerInOregon wrote:
Fri Feb 07, 2020 12:15 am
...
No auto constraints are created in the way the tutorial describes
...
There is an option in the task panel to create automatic constraints.

You should be creating a polyline, not single lines, Sketcher_CreatePolyline.
Always add the important information to your posts if you need help. Also see Tutorials and Video tutorials.
To support the documentation effort, and code development, your donation is appreciated: liberapay.com/FreeCAD.
chrisb
Posts: 27154
Joined: Tue Mar 17, 2015 9:14 am

Re: Newbie - Sketcher multiple line constraints

Postby chrisb » Fri Feb 07, 2020 2:24 am

If you struggle with sketcher you may find this tutorial useful.
PMac
Posts: 49
Joined: Sat Sep 02, 2017 10:44 pm

Re: Newbie - Sketcher multiple line constraints

Postby PMac » Fri Feb 07, 2020 4:46 am

makerInOregon wrote:
Fri Feb 07, 2020 12:15 am
So I follow the directions and a couple of things
No auto constraints are created in the way the tutorial describes
The lines are not linked (even when I start the next line highlight the end point of a previous line yellow)

I was able to manually select both end points and select the "Coincident constraint". Though I can't imagine that is what everyone does all the time. I assume this is a simple newbie kind of issue and your guidance would be appreciated.
Hi makerinOregon,

Had a squiz at the tutorial you have linked to. Yes indeed, the base shape before being padded is all single lines (and an arc).

To draw a new line joined to the last one, FreeCAD Sketcher relies on the user getting the mouse pointer over the end of the previous line where the dot turns yellow and then clicking to start the new line. Very tedious initially, but with practice you become very proficient at finding the end of the previous line.

Another way as mentioned in the tutorial text is to draw the new line adjacent to the previous one, then 'capture' the two ends and place a coincident constraint on the pair of adjacent line ends. You report being able to successfully select line end pairs and create the coincident constraint.

As for Auto constraints - In the task panel confirm the Auto Constraints checkbox is ticked. (I've found previously that even when it is ticked sometimes it does not appear to work consistently, so if it isn't working - cycle the tick off and re-tick the Auto Constraint checkbox) As you draw a line vertically (or horizontally) the line is auto-constrained to the vertical or horizontal. When you finish the line, a vertical or horizontal constraint will be automatically created in the list of constraints. As the line is being drawn when the line is rotated through the vertical or the horizontal, the auto constraint should show adjacent to the line.

Similarly, when drawing a new line from the previous one (yellow dot when mouse pointer is on the first line end) a coincident constraint will be automatically created upon 2nd line completion.

Believe me, it does get easier (I started drafting in pen and ink in the 70's), sketching is very powerful as you learn more features. I tend to draw all sketcher lines separate but adjacent of any length and in a rough direction, not coincident or horizontal/vertical. I then select the individual lines to create any orthogonality (vertical/horizontal) and angular constraints, then followed by end pairs to create coincident constraints along with length constraints.

Hope this helps.

PMac in NZ
chrisb
Posts: 27154
Joined: Tue Mar 17, 2015 9:14 am

Re: Newbie - Sketcher multiple line constraints

Postby chrisb » Fri Feb 07, 2020 6:34 am

PMac wrote:
Fri Feb 07, 2020 4:46 am
(I've found previously that even when it is ticked sometimes it does not appear to work consistently, so if it isn't working - cycle the tick off and re-tick the Auto Constraint checkbox)
In case you are interested in the reason behind this: If you change this checkbox, it will be stored in the sketch, while what you see is always the value from the preferences. This is known and will hopefully be corrected some day.
PMac
Posts: 49
Joined: Sat Sep 02, 2017 10:44 pm

Re: Newbie - Sketcher multiple line constraints

Postby PMac » Fri Feb 07, 2020 7:18 am

chrisb wrote:
Fri Feb 07, 2020 6:34 am
In case you interested in the reason behind this: If you change this checkbox, it will be stored in the sketch, while what you see is always the value from the preferences. This is known and will hopefully be corrected some day.
Hi chrisb - Thanks for that - good to see you are willing to explain the finer background detail in FreeCAD.

I often try to do things in various programs, mostly probably the wrong way and think so that's the way it works. Or maybe, that's not quite right - is it a 'feature' that needs to be watched for future improvement/regression or even a bug requiring reporting. The old story - from a lifetime of practical maintenance - if I have to read the documentation I'm in trouble!

One thing's for sure - I never stop learning with open-source.
Cheers PMac