Cutting a line / Problem

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Edduardo
Posts: 18
Joined: Fri Oct 04, 2019 5:44 pm

Cutting a line / Problem

Postby Edduardo » Sun Oct 13, 2019 2:36 am

Hello everyone! I was modeling a connecting rod (with a tutorial) and when I wanted to cut one line, with the option in the sketcher workbench, the line not just don´t get erased, but change the structure of the other lines. Am I´m not using this tool correctly? :/ Thanks for reading! (:

Image

Image

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13541 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 9948ee4f1570df9216862a79705afb367b2c6ffb
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: Spanish/Ecuador (es_EC)
chrisb
Posts: 19055
Joined: Tue Mar 17, 2015 9:14 am

Re: Cutting a line / Problem

Postby chrisb » Sun Oct 13, 2019 6:23 am

You seem to have used the Trim tool Image and this works indeed ... surprising, if the center of the circles is positioned with a point on line on the vertical line. Trimming results in an additional vertical line on top of the previous one, connected via tangency:
Snip macro screenshot-5a6517.png
Snip macro screenshot-5a6517.png (2.16 KiB) Viewed 193 times
Here I have removed the tangency to show what happens:
Snip macro screenshot-d75f16.png
Snip macro screenshot-d75f16.png (6.85 KiB) Viewed 193 times
Abdullah hasn't been very active recently so I think it is sensible to create a bug report in the tracker.
kisolre
Posts: 1360
Joined: Wed Nov 21, 2018 1:13 pm

Re: Cutting a line / Problem

Postby kisolre » Sun Oct 13, 2019 8:03 am

First prease if possible upgrade yout Freecad version at least to the latest stable - 0.18.3.
Second you should try to provide your file for examination. There are a number of ways that things can be constrained to visually display the same but which could create different results.
And finally Trim properly removes what it thinks is the central piece and leaves two end pieces. But then the solver kicks in and finds a valid solution. this might not be what you desire. So beter invoke those operations with minimally constrained sketch and when final geometry is achieved start to apply final constraints.
Here with not fully constrained sketch tool works as expected:
Trim.gif
Trim.gif (42.41 KiB) Viewed 188 times
OS: Windows 8.1 (6.3)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.18504 (Git)
Build type: Release
Branch: master
Hash: f66023a646db4b2502bb3637897443b3525ca3c7
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: Bulgarian/Bulgaria (bg_BG)
chrisb
Posts: 19055
Joined: Tue Mar 17, 2015 9:14 am

Re: Cutting a line / Problem

Postby chrisb » Sun Oct 13, 2019 9:26 am

Before applying the tool, is the point-on-line constraint in the center double, i.e. on the x-axis and on the vertical line or only on the x-axis?
kisolre
Posts: 1360
Joined: Wed Nov 21, 2018 1:13 pm

Re: Cutting a line / Problem

Postby kisolre » Sun Oct 13, 2019 10:01 am

chrisb wrote:
Sun Oct 13, 2019 9:26 am
Before applying the tool, is the point-on-line constraint in the center double, i.e. on the x-axis and on the vertical line or only on the x-axis?
Sorry for not providing a file. Here it is with double PointOnLine constraints.
1. Create arc, center PointOnLine to X axis
2. Create nonvertical line between arc ends.
3. Constraint line vertical.
4. Constraint center of arc to line (PointOnLine)
5. create internal arc, center coincident to first arc center, endc PoinyOnLine to vertical line from point 2.
6. Trim
Attachments
TrimBefore.FCStd
(5.01 KiB) Downloaded 6 times
chrisb
Posts: 19055
Joined: Tue Mar 17, 2015 9:14 am

Re: Cutting a line / Problem

Postby chrisb » Sun Oct 13, 2019 10:35 am

It doesn't seem to be the fully constrained sketch, it is rather the sequence of creating the elements and assigning constraints.

Trim both vertical lines in the attached sketch and they behave differently. At the right side I have clicked below the x-axis.
Snip macro screenshot-3fede8.png
Snip macro screenshot-3fede8.png (11.04 KiB) Viewed 167 times
Attachments
Trim_cb.FCStd
(3.77 KiB) Downloaded 7 times