Creating a new part with linked to the external geometry geometry

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hooshsim
Posts: 12
Joined: Mon Nov 05, 2018 7:40 pm

Creating a new part with linked to the external geometry geometry

Postby hooshsim » Thu Nov 22, 2018 7:03 pm

Hi,

I need some guidance on how to create a part and adding it to the existing (external) geometry (FreeCAD 0.17 Windows 7, Release 8/2018).

Please see attached FreeCAD file and couple of PNG snapshots describing the problem. Detailed help will be greatly appreciated.

HooshSim
Attachments
Fill1.PNG
Fill1.PNG (76.29 KiB) Viewed 305 times
Fill2.PNG
Fill2.PNG (90.54 KiB) Viewed 305 times
Filling.FCStd
(29.58 KiB) Downloaded 10 times
Bance
Posts: 206
Joined: Wed Feb 11, 2015 3:00 pm
Location: London

Re: Creating a new part with linked to the external geometry geometry

Postby Bance » Fri Nov 23, 2018 12:42 am

Hi Hooshsim,

I had a go at this, but it is not quite correct. The problem seems to be the B-Spline at the upper planar surface (curve B1,) which I had to approximate by eye.

I have a feeling this can be modeled, perhaps with the aid of the curves WB.

Any how, I used Part Cross-section to define A1,B1 and A2 (I had hoped to get B2 as well but no go! :( )

I then imported fusion into PD WB and created some data features, sketches and made an additive loft.

This models the prismatic feature you were looking for but is not parametric. I think if you start in PD WB and use a spreadsheet or some expressions, this could be made parametric.

I have included a file but i think I broke it when checking for its parametricicity (is that a word?)

Hope this plants a seed!

Looks like a turbine blade or something?

Steve.
FillingBance.png
FillingBance.png (57.24 KiB) Viewed 278 times
Attachments
FillingBance.FCStd
(159.48 KiB) Downloaded 6 times
hooshsim
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Joined: Mon Nov 05, 2018 7:40 pm

Re: Creating a new part with linked to the external geometry geometry

Postby hooshsim » Fri Nov 23, 2018 3:16 am

Steve,

I really appreciate your rapid reply. You are truly a life saver.

I am new to FreeCAD, if possible, can you provide more detailed description (perhaps step-by-step procedure) on how you created the datum planes? I tried to create them in PD WB but I'm getting errors.

Can you also add some notes on you created the ShapeBinders?

Thanks again and happy Thanksgivings - Hooshsim
Bance
Posts: 206
Joined: Wed Feb 11, 2015 3:00 pm
Location: London

Re: Creating a new part with linked to the external geometry geometry

Postby Bance » Fri Nov 23, 2018 4:18 am

Hooshim,

The way to examine a model presented as an example, is to use the space bar to make invisible all features(greyed out in the model tree)... then use the space bar to make visible each feature in turn, this gives the viewer the ability to follow the workflow.

As to creating the datum planes, simply select the face you wish the plane to be attached to and select the (datum plane)tool. Beware however, this is not best practice as it leaves the model susceptible to a bug in the OCC kernel which can break your model (look up 'topographical naming error'.)

Using a shape-binder makes external geometry available inside a body, select the required geometry (it is usually wise to hide anything extraneous to avoid mistakes,) then select the tool. In order to uttilise the shape-binder which is only a linked copy, one has to make it available in the sketch by using the external geometry tool.

I hope this allows you to proceed,

Steve.
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meme2704
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Re: Creating a new part with linked to the external geometry geometry

Postby meme2704 » Fri Nov 23, 2018 8:17 am

Hi
I make a cut attached to the flat face of each blade, it allows me to link a skit to the outer forms that suits me (sketch 013 and sketch014)
I make a loft between these two sketches, and merge with the primitive form
Attachments
turbine.FCStd
(100.49 KiB) Downloaded 7 times
turbine.PNG
turbine.PNG (43.33 KiB) Viewed 248 times
hooshsim
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Joined: Mon Nov 05, 2018 7:40 pm

Re: Creating a new part with linked to the external geometry geometry

Postby hooshsim » Fri Nov 23, 2018 1:32 pm

Meme,

Great job. I'm sort of new to FreeCAD. Can you give me more details (step by step) how you modeled my turbine geometry. I like your approach due to its simplicity.

Thanks in advance - Hooshsim
hooshsim
Posts: 12
Joined: Mon Nov 05, 2018 7:40 pm

Re: Creating a new part with linked to the external geometry geometry

Postby hooshsim » Fri Nov 23, 2018 1:47 pm

Meme,

How would you add another loft on the other side of the blade? Can you please extend your model to include a second loft? Thanks.
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meme2704
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Re: Creating a new part with linked to the external geometry geometry

Postby meme2704 » Fri Nov 23, 2018 4:15 pm

The simplest: you open my file and you clear step after step my job, if you want to go back to a higher operation, you do backtrack (yellow arrow to the left) etc.
You want to do another loft ... but what :?:
hooshsim
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Joined: Mon Nov 05, 2018 7:40 pm

Re: Creating a new part with linked to the external geometry geometry

Postby hooshsim » Sat Nov 24, 2018 4:16 pm

Hi meme,

After reviewing your turbine model, I am still confused about how you created sketch 13 and 14. Can you please guide me more on these sketches?

This will allow me to modify these sections to include additional fill on the other side of the blade (see snapshot below).

Thank you
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Capture.PNG
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meme2704
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Re: Creating a new part with linked to the external geometry geometry

Postby meme2704 » Sat Nov 24, 2018 5:38 pm

On the PGN I have already removed the piece of blade from the bottom, and I show how I tie the skit 12 to draw a square that is the base of a cube that I used to remove the top,
I only have the common part left to the two blades, on one of the faces I place as previously Sketch 13, and on the other Sketch 14,
I made a Loft between these two sketches and I re-melted with the basic blades.
If there is too much material, reopen sketch13 and sketch14 and remove the extra segments, without forgetting to completely close the sketches
Attachments
turbine-2.PNG
turbine-2.PNG (22.63 KiB) Viewed 166 times
turbine-1.PNG
turbine-1.PNG (44.27 KiB) Viewed 166 times
turbine1.FCStd
(103.03 KiB) Downloaded 5 times