Problems overwriting construction lines

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Vagulus
Posts: 850
Joined: Tue Jul 14, 2020 7:55 am
Location: Perth, Western Australia

Problems overwriting construction lines

Post by Vagulus »

OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/New Zealand (en_NZ)

Since I installed this new version I have had a persistent annoyance that overwriting a vertical construction line with a constrained edge inserts the vertical constraint on the new line which conflicts with the vertical constraint on the construction line. I get an error message that there is a redundant constraint - obviously, you don't need both of them. The same applies when overwriting horizontal construction lines. Perhaps you could call this a 'Bug'. It means that I can't do a series of overwrite lines and I have to remove the redundant constraint and restart line-draw each time. That's just a petty time-waster. Is there a fix?

Right now I have a similar problem with this sketch:
211017 Stiffener X-section.png
211017 Stiffener X-section.png (25.76 KiB) Viewed 2167 times
I am overwriting the construction lines and have stalled here. I need to overwrite the two arcs (red arrows) and the edge between them (between the two green arrows). I get all sorts of redundant constraints when I try. How do I get around this one?

Thanks
Attachments
211017 AP-00-000.FCStd
(13.24 KiB) Downloaded 34 times
"It is much harder to simplify than to complicate."
Joseph Kimble
chrisb
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Re: Problems overwriting construction lines

Post by chrisb »

You may have changed your settings. At th eleft side, under "Edit controls" you can check Auto constraints.
At your stage of knowledge I would not recommend to check "Auto remove redundants", because you cannot control which constraint will be removed.
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Vagulus
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Re: Problems overwriting construction lines

Post by Vagulus »

I had 'Auto constraints' checked
211017 Sketcher Settings.png
211017 Sketcher Settings.png (54.43 KiB) Viewed 2078 times
but that doesn't change things - I just tried with it unchecked. Note that I can draw in the vertical line (blue arrows)
211017 Stiffener X-section.png
211017 Stiffener X-section.png (27.05 KiB) Viewed 2078 times
and I only need to remove the new constraint. The other lines I mentioned create problems.
"It is much harder to simplify than to complicate."
Joseph Kimble
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Vagulus
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Re: Problems overwriting construction lines

Post by Vagulus »

FTR: I fixed the immediate problem by simplifying my sketch. The old story - "If it's complicated it's probably wrong!
211017 Stiffener X-section Simplified.png
211017 Stiffener X-section Simplified.png (17.64 KiB) Viewed 2053 times
However, that leaves the problem with redundant constraints while overwriting.
"It is much harder to simplify than to complicate."
Joseph Kimble
drmacro
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Re: Problems overwriting construction lines

Post by drmacro »

Vagulus wrote: Sun Oct 17, 2021 2:24 am FTR: I fixed the immediate problem by simplifying my sketch. The old story - "If it's complicated it's probably wrong!
211017 Stiffener X-section Simplified.png
However, that leaves the problem with redundant constraints while overwriting.
This sketch just begs to be reduced to the top or bottom symmetry and mirrored after padding. Which would simplify the sketch and constraint requirements.

But I'm sure you've thought of that.😎
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
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Shalmeneser
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Re: Problems overwriting construction lines

Post by Shalmeneser »

Vagulus wrote: Sat Oct 16, 2021 11:55 pm ...
Drawing on a constraint arc using [arc center+arc vertex+arc vertex] gives usually redondant constraints.
You need to draw with [arc center+arc vertex+new vertex on a line]. This other vertex can be on a tangent line

Picture example : [arc center+arc vertex+last vertex on the X-axis].
Attachments
Capture du 2021-10-17 22-54-49.png
Capture du 2021-10-17 22-54-49.png (5.9 KiB) Viewed 1898 times
arc over arc.FCStd
(12.94 KiB) Downloaded 41 times
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Vagulus
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Re: Problems overwriting construction lines

Post by Vagulus »

Thanks, Shalmeneser, but that's not the issue. The Arc you are overwriting is not constrained so your new arc (drawn unconstrained over the old arc) does not raise a 'redundant constraint' warning. Then when you do constrain the new arc that is the first and only constraint and no warning is required.

If you delete your new arc, then constrain the old arc (set it as a construction line) to 30mm radius and then draw a new arc over the (now) construction line you should get some redundant constraint issues. I did! :shock:
"It is much harder to simplify than to complicate."
Joseph Kimble
GeneFC
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Re: Problems overwriting construction lines

Post by GeneFC »

If you read my other recent posts it will be clear that I am a proponent of individuals following a style that feels comfortable, not some rigid set of "best practice" rules.

However, I question the style of sketching construction geometries and then retracing exactly over those construction geometries with real geometries. Any time one completely covers an underlying structure there could be issues.

I use construction geometries to outline limits and provide convenient attachment points for real geometries. I almost never trace over and obscure an entire construction feature.

Carry on as you wish, of course. Just offering a commentary.

Gene
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Vagulus
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Re: Problems overwriting construction lines

Post by Vagulus »

GeneFC wrote: Sun Oct 17, 2021 11:53 pm I use construction geometries to outline limits and provide convenient attachment points for real geometries. I almost never trace over and obscure an entire construction feature.
I agree completely. The example Shalmeneser and I are discussing is just that - an example.
"It is much harder to simplify than to complicate."
Joseph Kimble
domad
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Re: Problems overwriting construction lines

Post by domad »

Greetings to the Community!

With the (Win8) FC 0.20-25997 (standalone) version no problem.
I attach the file
Attachments
211017 AP-00-000.FCStd
(13.68 KiB) Downloaded 34 times
overwriting_construction_lines.gif
overwriting_construction_lines.gif (410.77 KiB) Viewed 1692 times
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