Nearly a wave spring washer ...

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triplus
Posts: 9475
Joined: Mon Dec 12, 2011 4:45 pm

Re: Nearly a wave spring washer ...

Postby triplus » Fri Mar 21, 2014 8:31 pm

I wonder if the part attached in first post is affected by something similar ruled surface once was. Automatic algorithm tried to check/guess everything but sometimes the wrong result was the outcome and user could not do much about it:

Image

viewtopic.php?f=19&t=4080&p=31966#p31939

After that wmayer added Orientation Property in the property view:

viewtopic.php?f=19&t=4080&p=31966#p31966

If automatic algorithm does not give expected result user can now override it. I was wondering if something like that would be needed for Loft feature? To control "Loft Flow" on individual segment to get expected result and to override automatic algorithm when needed? Probably something like that would be more complex to implement compared to ruled surface Orientation Property mentioned above?
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quick61
Posts: 3803
Joined: Sat Aug 24, 2013 2:49 am
Location: u.S.A.

Re: Nearly a wave spring washer ...

Postby quick61 » Fri Mar 21, 2014 8:40 pm

Now that's a good idea! It sure would go a long way to improving this sort thing. Lofting around an axis like this is most always a problem with start/end. Flow control would be a big improvement to the tool. Now, it it can only be done without having to rewrite the entire workbench...

Mark
This post made with 0.0% Micro$oft products - GOT LINUX?
ulrich1a
Posts: 1957
Joined: Sun Jul 07, 2013 12:08 pm

Re: Nearly a wave spring washer ...

Postby ulrich1a » Fri Mar 21, 2014 10:26 pm

I changed my macro to use one loft with 30°-steps. It gives a very good geometry, as I used a copy of the start wire as the last wire of the loft. But the problem is now, that the shape is invalid due to selfintersection. What is needed, is an option to use the first profile also as the last profile, in order to make an closed loft.
I tried it with append the first wire of the wirelist as last wire, but this crashed FreeCAD.
spring_washer_loft.png
Spring washer with loft method
spring_washer_loft.png (28.29 KiB) Viewed 1566 times
Here is also the python code to make the part.
Regards
Ulrich
Attachments
spring_washer2.py.zip
python code to make a spring washer with the loft method
(1.58 KiB) Downloaded 38 times
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NormandC
Posts: 18534
Joined: Sat Feb 06, 2010 9:52 pm
Location: Québec, Canada

Re: Nearly a wave spring washer ...

Postby NormandC » Sat Mar 22, 2014 12:47 am

The result is very nice, too bad the solid is invalid.

I ran the script, then exploded the shape object with the Draft Downgrade tool. This generated 6 faces, which is 2 too many.

I used the Part ShapeBuilder to create a new shell then a solid out of the 4 correct faces, but the geometry inspector advises the shell is "not closed". The problem is the joint line...
Attachments
spring_washer2_nc1.fcstd
Shape generated by ulrich1a's script, failed attempts to produce a solid out of it.
(18.95 KiB) Downloaded 40 times
ulrich1a
Posts: 1957
Joined: Sun Jul 07, 2013 12:08 pm

Re: Nearly a wave spring washer ...

Postby ulrich1a » Sat Mar 22, 2014 12:27 pm

normandc wrote:The result is very nice, too bad the solid is invalid.
Ok, I put a workaround into the scricpt. I let a small gap in the loft. Than make a second loft that fills the gap with some overlapping and fuse both parts.
This gives a valid solid at the cost of a longer runtime. An example part made with the script.
spring_washer_loft2.fcstd
Spring washer ISO BS 4463 for M5 made with loft scpript
(4.37 KiB) Downloaded 47 times
The script has a variable size. So the parts that are listed at http://www.springmasters.com/sp/wave-sp ... ers-4.html can be made with the script.
spring_washer3.py.zip
(1.65 KiB) Downloaded 43 times
I have a question now. Such a part is defined with its original thickness Lo as defined in the standard. When such part is used in an assembly, it will be typically deflected and has different dimensions. Is there a need for part-models with a certain degree of deflection? I was thinking about to add the script to the Screw_maker makro. So would there be a need for an additional deflection parameter?

Regards
Ulrich
chrisf
Posts: 212
Joined: Fri Jan 03, 2014 10:20 am

Re: Nearly a wave spring washer ...

Postby chrisf » Tue Mar 25, 2014 9:56 am

ulrich1a wrote:Ok, I put a workaround into the scricpt. I let a small gap in the loft. Than make a second loft that fills the gap with some overlapping and fuse both parts.
This gives a valid solid at the cost of a longer runtime. An example part made with the script.
spring_washer_loft2.fcstd
The script has a variable size. So the parts that are listed at http://www.springmasters.com/sp/wave-sp ... ers-4.html can be made with the script.
spring_washer3.py.zip
I have a question now. Such a part is defined with its original thickness Lo as defined in the standard. When such part is used in an assembly, it will be typically deflected and has different dimensions. Is there a need for part-models with a certain degree of deflection? I was thinking about to add the script to the Screw_maker makro. So would there be a need for an additional deflection parameter?
The part looks very good. I would think that just specifying different Lo would be enough to create parts at different deflections. I don't know how the parts deflect in reality and (whilst I've just started using Code Aster for fem work) I don't think a study of this washer can really be justified ;)