Parallel Arcs Sketcher to Part Design Problem

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kisolre
Posts: 1360
Joined: Wed Nov 21, 2018 1:13 pm

Re: Parallel Arcs Sketcher to Part Design Problem

Postby kisolre » Sun Mar 03, 2019 10:09 pm

For all those 0.125in constraints to be ok all your arcs centers are not constrained "COINCIDENT". The cleaner way should be that they are. You could box select the centers and apply coincident constraint to them and then have just a simple 0.125in length constraint somewhere for thickness of the sheet.
coincident.PNG
coincident.PNG (140.77 KiB) Viewed 198 times
chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Parallel Arcs Sketcher to Part Design Problem

Postby chrisb » Sun Mar 03, 2019 10:14 pm

Overconstraint sketches matter in 0.18. Please note that the notion of "overconstrained" is different from "sensible" or from repeating the same measure over and over.
chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Parallel Arcs Sketcher to Part Design Problem

Postby chrisb » Sun Mar 03, 2019 10:15 pm

You have "Auto remove redundants checked. That may have removed redundant constraints.
kisolre
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Joined: Wed Nov 21, 2018 1:13 pm

Re: Parallel Arcs Sketcher to Part Design Problem

Postby kisolre » Sun Mar 03, 2019 10:43 pm

ChrisB, that is an overlay over the picture that OP posted of his progress to show relevant tool (coincident constraint) and where to apply it. Not the actual sketch.
Gray Area
Posts: 20
Joined: Sat Nov 03, 2018 9:41 pm

Re: Parallel Arcs Sketcher to Part Design Problem

Postby Gray Area » Sun Mar 03, 2019 11:19 pm

The sketch and part shown on my last post was my first attempt at drawing a real part. Obviously, I have a long way to go on the Learning Curve.

For what it's worth, I'm an experienced 3D AutoCAD user. But, I like the design philosophy of FreeCAD with its parametric modeling. And although I'm experienced in modeling in 3D, again, I'm seeing a very steep learning curve in going from AutoCAD to FreeCAD.

As I need considerable "hands-on" practice, I'm going to redraw the sketch from scratch, attempting to simplify the constraints as I go along.

Again, I thank you all for your advice and help.

I'm certain this won't be my last plea for help on this forum.

Gray Area
chrisb
Posts: 19477
Joined: Tue Mar 17, 2015 9:14 am

Re: Parallel Arcs Sketcher to Part Design Problem

Postby chrisb » Mon Mar 04, 2019 12:08 am

Gray Area wrote:
Sun Mar 03, 2019 11:19 pm
As I need considerable "hands-on" practice, I'm going to redraw the sketch from scratch, attempting to simplify the constraints as I go along.
You can show us the result for further comments.

If you prefer geometric constraints over measures you made already half of the way. Have a look at the symmetry, you should get along without any measure on one of the sides.
Gray Area
Posts: 20
Joined: Sat Nov 03, 2018 9:41 pm

Re: Parallel Arcs Sketcher to Part Design Problem

Postby Gray Area » Mon Mar 04, 2019 12:33 am

kisolre wrote:
Sun Mar 03, 2019 10:09 pm
For all those 0.125in constraints to be ok all your arcs centers are not constrained "COINCIDENT". The cleaner way should be that they are. You could box select the centers and apply coincident constraint to them and then have just a simple 0.125in length constraint somewhere for thickness of the sheet.
coincident.PNG
I'm going to give that a try.

Thanks.
Gray Area
Posts: 20
Joined: Sat Nov 03, 2018 9:41 pm

Re: Parallel Arcs Sketcher to Part Design Problem

Postby Gray Area » Mon Mar 04, 2019 12:34 am

chrisb wrote:
Mon Mar 04, 2019 12:08 am
Gray Area wrote:
Sun Mar 03, 2019 11:19 pm
As I need considerable "hands-on" practice, I'm going to redraw the sketch from scratch, attempting to simplify the constraints as I go along.
You can show us the result for further comments.

If you prefer geometric constraints over measures you made already half of the way. Have a look at the symmetry, you should get along without any measure on one of the sides.
I just downloaded a couple of YouTube videos on symmetry.

Thanks for the advice.
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NormandC
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Location: Québec, Canada

Re: Parallel Arcs Sketcher to Part Design Problem

Postby NormandC » Mon Mar 04, 2019 4:29 am

Gray Area wrote:
Sun Mar 03, 2019 11:19 pm
And although I'm experienced in modeling in 3D, again, I'm seeing a very steep learning curve in going from AutoCAD to FreeCAD.
Having used AutoCAD in the past, that's definitely true. The whole parametric thing adds a level of complexity, as well as the constraint-based sketching. Not to mention that FreeCAD does not have a single, unified and polished UI. I've come to see it rather as a collection of different CAD approaches merged together. When you understand the distinctions between the approaches and learn how to take advantage of them, you can do a lot of things, but that'll require some time.

Speaking of approaches, one way to sketch your profile is to use the Image Sketcher Polyline tool and sketch straight segments, then use Image Sketcher Fillet on the corners. Then you'd make the outer and inner arcs concentric by setting coincident constraints to their centres.
Gray Area
Posts: 20
Joined: Sat Nov 03, 2018 9:41 pm

Re: Parallel Arcs Sketcher to Part Design Problem

Postby Gray Area » Mon Mar 04, 2019 1:29 pm

NormandC wrote:
Mon Mar 04, 2019 4:29 am
Gray Area wrote:
Sun Mar 03, 2019 11:19 pm
And although I'm experienced in modeling in 3D, again, I'm seeing a very steep learning curve in going from AutoCAD to FreeCAD.
Having used AutoCAD in the past, that's definitely true. The whole parametric thing adds a level of complexity, as well as the constraint-based sketching. Not to mention that FreeCAD does not have a single, unified and polished UI. I've come to see it rather as a collection of different CAD approaches merged together. When you understand the distinctions between the approaches and learn how to take advantage of them, you can do a lot of things, but that'll require some time.

Speaking of approaches, one way to sketch your profile is to use the Image Sketcher Polyline tool and sketch straight segments, then use Image Sketcher Fillet on the corners. Then you'd make the outer and inner arcs concentric by setting coincident constraints to their centres.
Thanks for the tip. I will give that a try.