ellipse in sketcher

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m0s1n
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ellipse in sketcher

Postby m0s1n » Wed May 21, 2014 3:45 pm

i figured out how to make the ellipse in draft and also as a primitive. the trouble is that when I make it that way, it becomes an edge(i think) instead of a face. I need a face that I can extrude up 10 mm to become the base of my model and I'd like that base to be an ellipse instead of squared off. I tried the draft to sketch tool, but it's not useful in this situation. The ellipse would not show up in the sketch. It was blank

OS: Ubuntu 12.04.4 LTS
Platform: 64-bit
Version: 0.14.3592 (Git)
Branch: master
Hash: 8106f8437c6ebcc66065c200d2c4d697fa18cf67
Python version: 2.7.3
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wmayer
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Re: ellipse in sketcher

Postby wmayer » Wed May 21, 2014 4:23 pm

Yes, ellipses and splines are currently not supported in the sketcher.
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m0s1n
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Re: ellipse in sketcher

Postby m0s1n » Wed May 21, 2014 4:30 pm

wmayer wrote:Yes, ellipses and splines are currently not supported in the sketcher.
do you know of another method to create the shape that I'd like?
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bejant
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Re: ellipse in sketcher

Postby bejant » Wed May 21, 2014 4:59 pm

Go into the Draft Workbench and make and ellipse, in the Data tab at the bottom left of the screen change the minor and major values to suit your needs. Select the ellipse in the tree view and then click the Bi-Directionally Convert Between Draft and Sketch Objects tool:
Image

Switch to Part Design WB and Pad the Sketch 10mm.
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m0s1n
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Re: ellipse in sketcher

Postby m0s1n » Wed May 21, 2014 5:19 pm

bejant wrote:Go into the Draft Workbench and make and ellipse, in the Data tab at the bottom left of the screen change the minor and major values to suit your needs. Select the ellipse in the tree view and then click the Bi-Directionally Convert Between Draft and Sketch Objects tool:
Image

Switch to Part Design WB and Pad the Sketch 10mm.
You know, I could have swore that i did those steps exactly before. Obviously I did not. The method you just described has worked. Thankyou.
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bejant
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Re: ellipse in sketcher

Postby bejant » Wed May 21, 2014 5:58 pm

Here's what I came up with. I used Sketcher rectangles converted to Draft objects so I could snap to the rectangle endpoints to make the ellipses, and there's some unused junk in the model I didn't clean up. And I cheated, the fillet is only 3.49mm ;)
20140521v_m0s1n.png
20140521v_m0s1n.png (9.02 KiB) Viewed 2888 times
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bejant
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Re: ellipse in sketcher

Postby bejant » Wed May 21, 2014 6:56 pm

Forgot to ask previously:
Are you going to build your Stirling Engine after modeling it?
Would you post some screen grabs of the model, and pics if you do build it?
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m0s1n
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Re: ellipse in sketcher

Postby m0s1n » Wed May 21, 2014 7:40 pm

I will build it, but it's going to take a while. I cant use the machines at work unless they arent dedicated to a job(not making any money). theres a nc lathe that i can use at almost any time but the mills usually only have about 1 hour of down time a week. so its going to be a slow process.


Im having trouble getting the fillet right. it seems that i should be able to do a negative radius and get what I want but i cant seem to do that. Any tips?
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bejant
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Re: ellipse in sketcher

Postby bejant » Wed May 21, 2014 9:52 pm

To do the fillet you want, first you need to have an inside corner to fillet:
20140521e_m0s1n.png
20140521e_m0s1n.png (9.7 KiB) Viewed 2852 times
Select the inside edge (green in the screen grab) and click the Fillet Tool.

That's why I made the model the way I did, here it is from the above screen grab. A 3.5mm fillet won't work but 3.49mm will, leaving a tiny .01mm leg on the vertical and horizontal faces.

Being able to make an inside fillet on an outside corner by inputting a negative value would be a nice FreeCAD feature.
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bejant
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Re: ellipse in sketcher

Postby bejant » Wed May 21, 2014 11:07 pm

I just found out an ellipse created in the Draft WB can be directly Padded in the Part Design WB without converting to a Sketch.

OS: Ubuntu 12.04.4 LTS
Platform: 32-bit
Version: 0.14.3624 (Git)
Branch: master
Hash: 581d88485dfab42292cdec63a6e0d34a216d772c
Python version: 2.7.3
Qt version: 4.8.1
Coin version: 3.1.3
SoQt version: 1.5.0
OCC version: 6.7.0