Challenge: Constant Velocity Joint (M. Gesik)

Discussion about the development of the Assembly workbench.
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Kunda1
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Challenge: Constant Velocity Joint (M. Gesik)

Postby Kunda1 » Sat Feb 29, 2020 3:24 pm

phpBB [video]
source: https://www.reddit.com/r/mechanical_gif ... ity_joint/
Thingiverse: https://www.thingiverse.com/thing:4191753
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ppemawm
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby ppemawm » Sun Mar 15, 2020 8:14 pm

OK, kunda1, I am taking your challenge but probably bit off more than I can chew. How could I possibly resist...

My plan is to reverse engineer the model from the individual STL files from thingaverse in PartDesign and assemble it using the Assembly4 workbench. I have created all the parts except for the geared links as shown in the original STL model below:

Picture1.jpg
The STL files were downloaded, saved, and imported to the FreeCAD file. The STL parts were then assembled using the Transform tool. Locating the geared links were the most difficult, two of which are shown here in approximate position. Please note the Creative Commons copyright attribution label.

My model started with the Assembly4 workbench and each part was created in-context referencing the STL model for sketch dimensions. Sketches were created 1:1 scale with the STL model in the background.

Assembly4 is basically a procedural wrapper for PartDesign which facilitates in-context design in a single file or bottom-up assembly from separate files. Using Assembly4 as a starting point has the advantage that when each Part is added a local coordinate system (LCS) is automatically added which will later facilitate assembly.
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Picture1.jpg (102.65 KiB) Viewed 2069 times
Picture2.jpg
These are the parts that I have created so far. They have not been assembled yet but were created in-context in their proper position by placing the sketches at their mating interface locations. Part and Body placement remains at 0,0,0.

Each Part LCS is located at the same interface for assembly later in Assembly4.
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Picture2.jpg (99.69 KiB) Viewed 2069 times
Picture3.jpg
This is an example of the master sketch used to create the somewhat complex 3-leg coupling. All of the features were created from this master sketch using Sketch > CarbonCopy. This saves a lot of sketch time as well as parametrically linking all the sketches if dimensional changes have to be made.
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Picture3.jpg (81.13 KiB) Viewed 2069 times
New Gif Animation.gif
This is a GIF of the order in which the features were created. The first frame is the original STL model. The last frame shows the STL model and the FreeCAD model trying to occupying the same space. Pretty darn close.
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New Gif Animation.gif (874.82 KiB) Viewed 2069 times
Picture4.jpg
These original STL models are the next two parts to be created before adding all of the fasteners and assembly with Assembly4. Not too sure how to get started with these yet, but that is something for another time this week.
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Picture4.jpg (88.44 KiB) Viewed 2069 times
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I already have several hours into these parts and expect there will be several more to create the geared links, add hardware, and assemble them in their proper position. File size is about 9 Mb so far.

Perhaps the CV joint can be animated with Assembly4 once complete, but I have no real clue how to do that yet. A very ingenious device...hats off to the inventor.


OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.20036 (Git)
Build type: Release
Branch: master
Hash: 953ae1e6e917fa6860564c80fdc1f20950a5c0ac
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)
"It is a poor workman who blames his tools..." ;)
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Kunda1
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby Kunda1 » Sun Mar 15, 2020 8:22 pm

Image
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OficineRobotica
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby OficineRobotica » Tue Mar 17, 2020 5:51 am

WOOOOW......beutiful. Living in Italy I also appreciate the beuty of the screenshots especially the one with the sketch overlayed . Hats off.
HoWil
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby HoWil » Sat Mar 21, 2020 4:22 pm

ppemawm wrote:
Sun Mar 15, 2020 8:14 pm
File size is about 9 Mb so far.
Nice work! Really well made pictures.
Would like to give it a +1 or eqivalent if the forum would allow :!: :?
Is this file size probably with all the mesh data included?
If so, whats without mesh?

BTW: @Kunda1 where to suggest one of these pics as 0.19 startup pic.
BR
Howil
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Kunda1
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby Kunda1 » Sat Mar 21, 2020 4:45 pm

HoWil wrote:
Sat Mar 21, 2020 4:22 pm
BTW: @Kunda1 where to suggest one of these pics as 0.19 startup pic.
@Howil maybe https://forum.freecadweb.org/viewtopic.php?f=10&t=34586 ?
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HoWil
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby HoWil » Sat Mar 21, 2020 7:13 pm

Thx. Done.
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ppemawm
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Re: Challenge: Constant Velocity Joint (M. Gesik)--UPDATE

Postby ppemawm » Sun Mar 22, 2020 12:03 am

Thank you for your kind comments.
HoWil wrote:
Sat Mar 21, 2020 4:22 pm
Is this file size probably with all the mesh data included?
If so, whats without mesh?
Yes it was, but the file has grown to 16.1 Mb after completing two of the six geared links. With the .stl files stripped it is 14.5 Mb.
The geared links were a real challenge. They took several hours of fiddling in order to get a valid solid that closely duplicated the original.

biellettePA_sketch.JPG
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This is an example of a carboncopy of the master sketch used for most of the features other than the gear teeth. The construction circles were used to accurately position the transparent .stl reference object in the background during modelling.
biellettePA_sketch.JPG (184.51 KiB) Viewed 1656 times
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biellettePA.JPG
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I started with a PartDesign > clone of a 20 deg bevel gear from the Gear workbench and sectioned what was needed for a PartDesign > boolean with the rest of the link. A clone is used so that it could be independently positioned for overlay of the .stl object during modelling. It seems as though the bevel gear reference changes positions every time you adjust the gear parameters!

Also, for some reason the gear reference is duplicated during the boolean but without any error report.
biellettePA.JPG (228.69 KiB) Viewed 1656 times
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Three of the links are mirror images of the other three. I tried a Part > mirror but think that a PartDesign > Link mirror may be better.
Assembling all the Parts this week with Assembly4 is next. Hoo boy....we're having fun now.

OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.20036 (Git)
Build type: Release
Branch: master
Hash: 953ae1e6e917fa6860564c80fdc1f20950a5c0ac
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/United States (en_US)
"It is a poor workman who blames his tools..." ;)
HoWil
Posts: 1199
Joined: Sun Jun 14, 2015 7:31 pm
Location: Austria

Re: Challenge: Constant Velocity Joint (M. Gesik)--UPDATE

Postby HoWil » Sun Mar 22, 2020 7:47 am

ppemawm wrote:
Sun Mar 22, 2020 12:03 am
The geared links were a real challenge. They took several hours of fiddling in order to get a valid solid that closely duplicated the original.
Do you know the "Mesh Remodel workbench" ? Maybe it is helpful.
https://forum.freecadweb.org/viewtopic.php?f=9&t=38670

I like that you used Gears. I wondered if you will =). Please consider reporting you issues. It will help us in the future with similar issues.
ppemawm wrote:
Sun Mar 22, 2020 12:03 am
Assembling all the Parts this week with Assembly4 is next.
Can you please elaborate on why you use ASM4? Never used it until now but I would have used ASM3 without thoughts.
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ppemawm
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Re: Challenge: Constant Velocity Joint (M. Gesik)

Postby ppemawm » Sun Mar 22, 2020 3:25 pm

HoWil wrote:
Sun Mar 22, 2020 7:47 am
Do you know the "Mesh Remodel workbench" ?
Only vaguely, but it looks like it should be helpful for reverse engineering .stl files. Almost like cheating, but thank you for reminding me for next time.
HoWil wrote:
Sun Mar 22, 2020 7:47 am
I like that you used Gears. I wondered if you will =). Please consider reporting you issues.
I think I understand why the bevel gear changes position when the gear parameters are changed as it should for normal usage. In my case, the gears are not meshed in a normal manner. A PartDesign > Clone solved the problem nicely since it has independent placement and retains its link to the gear parameters.
HoWil wrote:
Sun Mar 22, 2020 7:47 am
Can you please elaborate on why you use ASM4?
Assembly4 facilitates my modelling process of in-context, top-down, mastersketch-driven assembly design that I have used since V0.13. Also, it is quite simple to use and meets 90% of my needs including animation of articulating mechanisms using the sketcher solver. Once Assembly3 is added as a standard workbench I may look into it for those 10% of cases that ASM4 can't solve. I do not know yet if ASM4 can articulate the CV joint so may need ASM3 sooner than later.
"It is a poor workman who blames his tools..." ;)