Block Constraint

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chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Block Constraint

Postby chrisb » Sat Mar 10, 2018 8:37 am

In my garage it is strictly forbidden to use screwdrivers to do anything else but turning screws, especially it is forbidden to hammer on a screwdriver (that's why my son got his own set). The reason is, that they wear out. Luckily the FreeCAD tools don't wear, the y work every day as if they where just ordered. :)
abdullah
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Joined: Sun May 04, 2014 3:16 pm

Re: Block Constraint

Postby abdullah » Sat Mar 10, 2018 11:00 am

triplus wrote:
Sat Mar 10, 2018 2:04 am
P.S. Or you didn't speak metaphorically. And you had an actual screwdriver and a chisel in mind? :ugeek:
It is not metaphorical. I used to do it at lot (hammer+screwdriver), as we did not have chisels. We did not have tiny screwdrivers either, so the point of knives (not forks) was used instead. This led to ...
chrisb wrote:
Sat Mar 10, 2018 8:37 am
In my garage it is strictly forbidden to use screwdrivers to do anything else but turning screws, especially it is forbidden to hammer on a screwdriver (that's why my son got his own set). The reason is, that they wear out. Luckily the FreeCAD tools don't wear, the y work every day as if they where just ordered.
... exactly, we have a winner!, never ever having a suitable screwdriver (and no pointy knives, but that can be a feature, only you needed another pointy knife for the next set tiny screws and ended up destroying all the knives in the house)!!

While I was reading triplus, I was exactly thinking that, FC tools do not wear out. Cool!!! :lol:
chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Block Constraint

Postby chrisb » Sat Mar 10, 2018 11:19 am

abdullah wrote:
Sat Mar 10, 2018 11:00 am
While I was reading triplus, I was exactly thinking that, FC tools do not wear out. Cool!!! :lol:
FC tools are like a butcher's knives: if they are regularly resharpended they get better and better!
FreeCAD, a butcher's tool: http://www.cooknsoul.de/wp-content/uplo ... 20x440.jpg
triplus
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Re: Block Constraint

Postby triplus » Sat Mar 10, 2018 8:39 pm

OK therefore in the garage it is strictly forbidden the use of hammer and screwdriver. FreeCAD on the other hand is more forgiving. :lol:

P.S. I did see experienced handyman using a combination of hammer and screwdriver in the past. And i must say in the circumstances it made perfect sense and it did the job just fine. Therefore likely just as when it comes to FreeCAD. In real life things can get tricky too. :idea:
ulrich1a
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Joined: Sun Jul 07, 2013 12:08 pm

Re: Block Constraint

Postby ulrich1a » Sat Apr 14, 2018 6:44 pm

I have used the block constraint, to fix an "artistic" b-spline. But I got later problems, when I tried to constrain another b-spline to the blocked one. It does just not work. Those constraints are just not added to the sketch. This is misleading, when you think you constrained it with an auto-constraint.

Is this the intended behavior, or is this a bug?

Ulrich
abdullah
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Joined: Sun May 04, 2014 3:16 pm

Re: Block Constraint

Postby abdullah » Sun Apr 15, 2018 8:18 am

ulrich1a wrote:
Sat Apr 14, 2018 6:44 pm
I have used the block constraint, to fix an "artistic" b-spline. But I got later problems, when I tried to constrain another b-spline to the blocked one. It does just not work. Those constraints are just not added to the sketch. This is misleading, when you think you constrained it with an auto-constraint.

Is this the intended behavior, or is this a bug?

Ulrich
Hi Ulrich!

As you describe it it seems like a bug. Could you post an example so as investigate it?

P.S.: Please, quote me, as I am just notified on quotes and PMs :)
abdullah
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Re: Block Constraint

Postby abdullah » Sun Apr 15, 2018 8:34 am

ulrich1a wrote:
Sat Apr 14, 2018 6:44 pm
I have used the block constraint, to fix an "artistic" b-spline. But I got later problems, when I tried to constrain another b-spline to the blocked one. It does just not work. Those constraints are just not added to the sketch. This is misleading, when you think you constrained it with an auto-constraint.

Is this the intended behavior, or is this a bug?

Ulrich
No need to post an example. I have reproduced it. It is "half a bug".

It is one of the many issues that happen because the center of the pole is coincident on the endpoint of the bspline, but it is over the endpoint and thus it is always picked by coin.

What is happening

The autoconstraint or constraint is applied to the pole, not to the endpoint of the bspline. The underlaying logic is: Internal geometry defines a complex geometry element. When this complex element is blocked, internal geometry does not define anything and is blocked. It might or might not be necessary to introduce an exception here for some cases, like this one. I have to study it further to see all the implications.

The work-around

Use the Elements Widget to select the endpoints of the two b-splines (hover over the first bspline, press 'z' until the point you want gets highlighted, click, hover to the second b-spline, press 'z' until the point you want gets highlighted, press 'ctrl' and click, to add the second point to the selection, hit the coincident constraint).

If somebody files a bug and assigns to me in the tracker the chance I forget about this will get significantly lower. :)

Thanks for reporting this :) :) :)
abdullah
ulrich1a
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Re: Block Constraint

Postby ulrich1a » Mon Apr 16, 2018 8:53 pm

abdullah wrote:
Sun Apr 15, 2018 8:34 am
If somebody files a bug and assigns to me in the tracker the chance I forget about this will get significantly lower.
I filed a bug report: https://freecadweb.org/tracker/view.php?id=3433

Ulrich
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NormandC
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Location: Québec, Canada

Re: Block Constraint

Postby NormandC » Tue Apr 17, 2018 12:20 am

abdullah wrote:
Sun Apr 15, 2018 8:34 am
If somebody files a bug and assigns to me
Friendly reminder: reporters cannot assign bugs to developers. Only managers and developers can assign bugs. Those are types of access levels. Most Mantis accounts are of reporter access level.

ulrich1a wrote:
Mon Apr 16, 2018 8:53 pm
I filed a bug report
I assigned it to abdullah.
abdullah
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Joined: Sun May 04, 2014 3:16 pm

Re: Block Constraint

Postby abdullah » Tue Apr 17, 2018 8:09 am

NormandC wrote:
Tue Apr 17, 2018 12:20 am
abdullah wrote:
Sun Apr 15, 2018 8:34 am
If somebody files a bug and assigns to me
Friendly reminder: reporters cannot assign bugs to developers. Only managers and developers can assign bugs. Those are types of access levels. Most Mantis accounts are of reporter access level.
I did not know. The good think is that you managers are overall in the forums, so there is always a helping hand around ;)