one section off sketch vid 09

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FC-Architecter
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one section off sketch vid 09

Postby FC-Architecter » Sun Jul 01, 2018 7:34 pm

OS: Linux Mint 18.3 Sylvia
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13522 (Git)
Build type: None
Branch: releases/FreeCAD-0-17
Hash: 3bb5ff4e70c0c526f2d9dd69b1004155b2f527f2
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedStates (en_US)


In the video, the sketch was almost finished but the lower left corner of my sketch was off

The upper curve of the lower left side of the switch does not seem to be connected correctly.

I thought the video should have connected the end of the big arc on the left to the small fillet with a coincident constraint. and the video seemed to select the end points of the two lines but the video used "Fix a point onto an object."

Now I have still 3 degrees of freedom, and I think this is one problem because the fillet is still movable. If I add an equality constraint to the fillets at both sides of the switch, Solver tells me to delete it.

Any suggestions appreciated.
FILLET_LOWER_LEFT_LOOKS_OFF.png
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09_AFTER_1st_Drawing.fcstd
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Last edited by FC-Architecter on Tue Jul 03, 2018 6:05 pm, edited 1 time in total.
chrisb
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Re: one section off sketch vid 09

Postby chrisb » Sun Jul 01, 2018 11:47 pm

Use tangents at the endpoints of the marked arc instead of coincidence. Furthermore you should again(!) delete the automatically generated horizontal constraint which is implied by the symmetry.

I would recommend again to use the latest 0.18 version. Sketcher's improvemements would save you and us much time and adrenaline.
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Re: one section off sketch vid 09

Postby FC-Architecter » Mon Jul 02, 2018 5:01 pm

chrisb wrote:
Sun Jul 01, 2018 11:47 pm
Use tangents at the endpoints of the marked arc instead of coincidence. Furthermore you should again(!) delete the automatically generated horizontal constraint which is implied by the symmetry.
As you know vid 09 puts in the horizontal constraint before the small arc is attached to the larger. The horizontal constraint is not automatic, it is put in manually in the video, and it is put in before the upper corner arc is attache to large arc.

I just tried selecting the LINE not the endpoint of the large arc, then the endpoint of the small arc and using the TANGENT constraint. The operation succeeded but the points were still separated in space, so I also had to use the coincident constraint anyway.

As you know, the entire lower left corner of the sketch was put in last, so the whole thing can be removed and redone.
chrisb wrote:
Sun Jul 01, 2018 11:47 pm
I would recommend again to use the latest 0.18 version. Sketcher's improvemements would save you and us much time and adrenaline.
It looks like there may be some problems with 0.18. Is it stable? We are advised in Linux Mint to wait until the Linux Mint guys put software into their repository. Version 0.18 has not shown up yet.

Ok Ok mea culpa. I am slowly figuring things out. I have got it down to 1 degree of freedom. Just searching for it now. The lower left corner is still moving so that must be the remaining degree of freedom.
STILL_MOVING.png
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Last edited by FC-Architecter on Mon Jul 02, 2018 5:43 pm, edited 4 times in total.
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NormandC
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Re: one section off sketch vid 09

Postby NormandC » Mon Jul 02, 2018 5:13 pm

FC-Architecter wrote:
Mon Jul 02, 2018 5:01 pm
It looks like there may be some problems with 0.18. Is it stable? We are advised in Linux Mint to wait until the Linux Mint guys put software into their repository. Version 0.18 has not shown up yet.
0.18-dev builds upon v0.17 and its development started back in April. So far it is not less stable than 0.17, and it actually brings improvements and bug fixes. But as time passes, it's possible that new code could add further bugs... After all, it is a development version.

As for the LinuxMint guys... LOL. They do not provide freecad in their repositories, they leech off Ubuntu repositories for most of their software. Ubuntu does not keep up with freecad development, they have a 6 month release cycle with versions in April and October, and they stop accepting versions of software maybe a month before a release; if a FreeCAD release misses that deadline, then it is not included. With LTS versions, for example 18.04, they stay with the old version for the duration of support (5 years). Which is why we provide a Ubuntu PPA repository.

I'm over-simplificating a bit, but that's the gist of it.
chrisb
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Re: one section off sketch vid 09

Postby chrisb » Mon Jul 02, 2018 8:14 pm

FC-Architecter wrote:
Mon Jul 02, 2018 5:01 pm
I just tried selecting the LINE not the endpoint of the large arc, then the endpoint of the small arc and using the TANGENT constraint. The operation succeeded but the points were still separated in space, so I also had to use the coincident constraint anyway.
I know how it happens, but nevertheless you should avoid it. If you want the ends of two lines/arcs to be tangent then select the endpoints and apply tangency, and apply no other constraint. Period. Whatever else you have seen, heard or done: it's wrong.
As you know, the entire lower left corner of the sketch was put in last, so the whole thing can be removed and redone.
You have modeled enough to avoid to restart over and over again. You should now find the reasons why things don't work and fix them. It's not some kind of gambling where you sometimes win and sometimes loose. Understand where the issues arise from and fix them. That makes you a winner every time.
It looks like there may be some problems with 0.18. Is it stable? We are advised in Linux Mint to wait until the Linux Mint guys put software into their repository. Version 0.18 has not shown up yet.
It seems to be as stable as my 0.17. I'm not familiar with Mint, but you can always use the Appimage
Ok Ok mea culpa. I am slowly figuring things out. I have got it down to 1 degree of freedom. Just searching for it now. The lower left corner is still moving so that must be the remaining degree of freedom.
I told you in my previous post what to do to fully constrain the sketch. See above. You applied the tangency only at one end of the arc.
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Re: one section off sketch vid 09

Postby FC-Architecter » Tue Jul 03, 2018 10:28 am

chrisb wrote:
Mon Jul 02, 2018 8:14 pm
I told you in my previous post what to do to fully constrain the sketch. See above. You applied the tangency only at one end of the arc.
Yes, I realized that I had confused the "fix point to object" with "tangency" because they look similar.

I removed both constraints (1. coincidence and 2. fix point to object) I had put on the upper end of the small arc and replace them with one tangency constraint.

This left me with 1 DOF.
I did not realize that I should fix BOTH ends of the small arc. Is this how you always have to fix a fillet to a straight line segment?

Presumably if I remove the coincidence constraint from the lower point of the small arc, I will have no dof and I can closed sketcher.

Yes, that did it thanks to you. The sketch has gone green.

Maybe you can tell me why a tangent constraint works there but a coincident does not. I still don't get this.

sketch_09_goes_green.png
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if you check video tutorial 09 made by bejant, there is a horizontal constraint on the short line segment. Are you saying I should delete this?
HORIZONTAL_CONSTRAINT_IN_TUTORIAL09.png
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chrisb
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Re: one section off sketch vid 09

Postby chrisb » Tue Jul 03, 2018 1:15 pm

FC-Architecter wrote:
Tue Jul 03, 2018 10:28 am
if you check video tutorial 09 made by bejant, there is a horizontal constraint on the short line segment. Are you saying I should delete this?
No, there is a symmetry constraint at the top of the sketch. That has an additional horizontal constraint.
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Re: one section off sketch vid 09

Postby FC-Architecter » Tue Jul 03, 2018 3:45 pm

chrisb wrote:
Tue Jul 03, 2018 1:15 pm
FC-Architecter wrote:
Tue Jul 03, 2018 10:28 am
if you check video tutorial 09 made by bejant, there is a horizontal constraint on the short line segment. Are you saying I should delete this?
No, there is a symmetry constraint at the top of the sketch. That has an additional horizontal constraint.
Yes, at minute 11:14 you can see the symmetry constraint and the horizontal constraint in the video 09.

Are you saying it should be deleted

HORIZONTAL_CONSTRAINT_IN_VID09.png
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Re: one section off sketch vid 09

Postby FC-Architecter » Tue Jul 03, 2018 4:57 pm

about at minute 17:10 in the video a new sketch is made on the face of the 2nd pad

the video selects the edge of the hole in the pad and clicks "make a link to external geometry"

then makes a circle establishing its center at the center of the hole. apparently that made a coincidence between the center of the hole and the center of the new circle.

But when I did that, not coincident point was made.

I still had one degree of freedom after the circle was made and I should have closed the sketch. I checked the circle and its center was not coincident with the center of the hole, so I had to make another coincidence. I did it a second time and the same thing happened.

Another strange thing: near the end of the video the 2nd sketch is edited and some changes are made in dimensions then changed back to the originals. But when I closed the sketch, the pocket and the refine shape had been undone so I had to redo them.

The Dependency Graph does not look like that in the video. Still don't quite understand how to deal with the red lines, other than creating another body. What's important I am guessing is whether a file can be used by the engineers and builders.

It looks like this one is done without anything exploding.
MY_DEPENDENCY_GRAPH_VID09.png
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I think some things done in video 09 messed up the pocket. So I should have deleted the pocket in tree view and created a new one. but I don't understand why bejant's action in changing the dimensions did not create the problem that I had.
Last edited by FC-Architecter on Wed Jul 04, 2018 7:19 pm, edited 1 time in total.
chrisb
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Re: one section off sketch vid 09

Postby chrisb » Wed Jul 04, 2018 12:44 am

FC-Architecter wrote:
Tue Jul 03, 2018 3:45 pm
Are you saying it should be deleted
Yes, delete that horizontal constraint.

May I ask why you want confirmation for that? You could test it yourself and see that after deletion the sketch is still fully constrained.