how to create half sphere on choosen face of a 3d object?

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shivmsit
Posts: 6
Joined: Sat Oct 15, 2016 6:23 pm

how to create half sphere on choosen face of a 3d object?

Postby shivmsit » Sat Oct 15, 2016 6:43 pm

I am new to FreeCad and playing around with it for 2 weeks. I am comfortable to create 3d with sketch and doing operations in part design workbench. I had created a model and now I want to put a half sphere on a face of a rectangular 3d shape. If I create half sphere in part workbench it always created on origin and its very cumbersome to position it at desired location in 3d space. Is there any way to create half sphere on selected face by creating a sketch or something else?

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DeepSOIC
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Location: Saint-Petersburg, Russia

Re: how to create half sphere on choosen face of a 3d object?

Postby DeepSOIC » Sat Oct 15, 2016 6:56 pm

Hi!
This can be done by a sketch using PartDesign.
1. Select face, create new sketch
2. draw a construction line to serve as revolution axis
3. draw and constrain a closed profile of a semi-circle, that when revolved around axis will produce a sphere.
4. PartDesign Revolution. This will make a sphere, but the sphere will be fused to the model (i.e. a hemispherical protrusion will be added to your boxy shape).

If you don't absolutely need that sphere to be parametrically linked, you can use a macro to make an actual Part Sphere in the clicked place.
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NormandC
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Re: how to create half sphere on choosen face of a 3d object?

Postby NormandC » Sat Oct 15, 2016 7:08 pm

EDIT: DeepSOIC was faster! But I added images and a file. ;)
shivmsit wrote:Is there any way to create half sphere on selected face by creating a sketch or something else?
It is possible, in the Part Design workbench. The steps are: create a sketch of a half-circle, then apply a revolution to the sketch.
  1. First select the face on which you want to make the half-sphere, then click on Image "Create new sketch".
  2. Draw a line and an arc in the sketch forming a closed half circle (I made it in a single step using the Image Sketcher Polyline tool). If the intended revolve axis does not lie on one of the sketch axes, add a construction line to serve as revolution axis. It is important that the closed profile does not intersect the revolution axis.
    FC_PD_Half-sphere_01.png
    FC_PD_Half-sphere_01.png (13.91 KiB) Viewed 1458 times
     
  3. Create a Image PartDesign Revolution. Adjust the parameters as needed. If you created a construction line to be used as revolution axis, it will be available in the Axis dropdown as "Sketch axis 0".
    FC_PD_Half-sphere_02.png
    FC_PD_Half-sphere_02.png (37.32 KiB) Viewed 1458 times
Attachments
PartDesign_Revolution_half-sphere.normandc1.fcstd
(14.87 KiB) Downloaded 12 times
shivmsit
Posts: 6
Joined: Sat Oct 15, 2016 6:23 pm

Re: how to create half sphere on choosen face of a 3d object?

Postby shivmsit » Sat Oct 15, 2016 7:39 pm

Thank you DeepSOIC for quick answer and thank you NormandC for your great illustrative explanation. This is really very helpful and solved my problem.
ScheissSchiesser
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Joined: Fri Dec 21, 2018 10:14 pm

Re: how to create half sphere on choosen face of a 3d object?

Postby ScheissSchiesser » Fri Dec 21, 2018 11:12 pm

Hi There,

I am trying to create a fillister slotted screw head (https://www.amesweb.info/Fasteners/Mach ... -Head.aspx) and I am having a heck of a time creating the partial spherical cap. I have tried to revolve a cross section but I get an error saying that the axis of rotation goes through the sketch.

The solution given here only works for a hemisphere, not a smaller section of a sphere.

Is it possible to adapt this principle to a smaller section?

I have attached the file with a cross-section sketch. Any tips would be greatly appreciated.
Attachments
CO2_knob.FCStd
(8.06 KiB) Downloaded 5 times
chrisb
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Re: how to create half sphere on choosen face of a 3d object?

Postby chrisb » Sat Dec 22, 2018 1:41 am

Hi ScheissSchiesser, welcome to the forum; nice user name.
Revolving is a great idea. You must not sketch a whole section, but only half of it and revolve it 360°. See PartDesign Revolution.
ScheissSchiesser
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Joined: Fri Dec 21, 2018 10:14 pm

Re: how to create half sphere on choosen face of a 3d object?

Postby ScheissSchiesser » Mon Jan 21, 2019 3:38 am

Thank you for the help. Seems obvious in retrospect!

Attached is the final design I was after. I used the model of the fillister head as a digital "mold" (with a tiny offset) to make a fitted thumb screw. I 3D printed it and it works great!
Attachments
CO2_knob.FCStd
(49.38 KiB) Downloaded 9 times