6 spoke flywheel in FreeCAD

This topic has 8 replies, 5 voices, and was last updated 6 February 2026 at 17:06 by lee webster.

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3 February 2026 at 15:31 #835717
lee webster
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@leewebster72680
A recent topic discussing flywheels in freeCAD prompted me to have a break from learning SolidEdge and try FreeCAD again. I tried different releases of FC before settling on version 1.0 To say the result was dissapointing and rather messy would be an understatement. This is a closeup of one of the spokes. I selected the spoke to highlight it to better show the distortion. (I had also split the flywheel as if to use as a pattern for casting) The fillets are also quite large and worked between the spokes. Better pictures are available if wanted.

I then converted it into a mesh in FC. Very little of the distortion is visible. (Full flywheel, no split).

And this is the split flywheel in Cura5 ready for printing. I enlarged the STL file 50% to give a 70mm dia flywheel. The distortion is minimal.

I 3D printed the STL at a high resolution (.12 I think) and the print shows no sign of distortion, even in PLA. The print was difficult to photograph because the PLA is white. If I was going to use the print for a casting it would take very little work to smooth the surfaces. I don’t use FreeCAD because of its many “foibles?”. But if I could no longer use DesignSpark Mechanical or SolidEdge, I would use FreeCAD, unless I had enough money to buy a good CAD package.

Lee
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3 February 2026 at 15:55 #835730
DC31k
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@dc31k
On 3 February 2026 at 15:31 lee webster Said:

I selected the spoke to highlight it to better show the distortion.

What you see displayed on screen is an artifact of how the screen is rendered. As your subsequent activities show, it is not part of the 3D geometry.
3 February 2026 at 16:46 #835744
Wade Beatty
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@wadebeatty78296
<p style=”text-align: left;”>Solid Edge community is also free, and a proper Cad program</p>
5 February 2026 at 09:58 #836167
lee webster
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@leewebster72680
DC31k

I tried different designs of flywheel and they all displayed as above, but would be perfect when exported as an STL file.

When working on a design that had curved spokes, I modified a sketch and the model dissapeared, no error was displayed. I was using version 1. I tried the “eye” and spacbar to activate each part, including the body, but nothing would display. My computer that I use for CAD work isn’t connected to the internet, it runs faster that way, so I couldn’t go online for advice. I wasn’t sure what caused the dissapearence so I unloaded ver1 and installed ver .19. That wouldn’t display the model. I also tried ver .18. No luck. I don’t know if the drawings in FreeCAD are backwards compatible, they aren’t in SolidEdge.

I will keep ver .18 installed as it is a very handy file converter, and I like using FreeCAD now and then. I will download the latest version to try when released.

Lee
5 February 2026 at 12:15 #836246
Roger Woollett
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@rogerwoollett53105
Lee

I think you have hit a known bug in FreeCAD which affects Polar Patterns where the spokes have a negative taper. There may well be other manifestations. The bug has been reported and is been worked on.

As you have found FreeCAD has evolved a lot. In my limited experience versions before 1.0 tended to be unstable and the user interface kept changing. This meant that YouTube tutorials often had a different interface to the one I was using.

Version 1 is much more stable and the tutorials are likely to show the same interface as you see.The current stable version is 1.0.2

Version 1.1 is being worked on and you can download release candidate 2.This brings some useful improvements but is not a dramatic change from 1.0.

I use it (not frequently) because it runs under Linux on a Raspberry Pi5 quite happily.
5 February 2026 at 21:07 #836351
lee webster
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@leewebster72680
Thanks Roger, I installed 1.0.2 and opened the flywheel file. The eye icon was inactive next to “Body”, I clicked on it and the flywheel appeared. I added a range of fillets and this is the result. First image isn’t shaded, the second image is.

I am impressed! I will do more exploration in FreeCAD.

Lee
6 February 2026 at 06:47 #836422
JasonB
Moderator
@jasonb
Lee, try it with draft on the hub and rim which is what you would need if it were a pattern
6 February 2026 at 09:54 #836449
lee webster
Participant
@leewebster72680
Jason,

The outer rim has a curve added after drawing the whole thing. The inside doesn’t beacause I was only drawing this flywheel to see if it would do curved spokes. The spokes are round and not oval. I will redraw the flywheel with draft (it isn’t really draft, I just make the inner and outer faces of the rim curved, and the outer face of the hub), oval spokes, and extended faces to allow for machining. I will also split the flywheel and add locating holes in the split faces so the halves can be used as a casting pattern. This should be interesting.

Lee
6 February 2026 at 17:06 #836528
lee webster
Participant
@leewebster72680
I am sorry to say that I failed with drawing a 6 spoked flywheel with curved spokes AND fillets. I drew the whole thing as planned, selected an edge between two spokes, hit the fillet button, and FreeCAD froze. I had to exit the programme and when I restarted it FreeCAD restored the file to where it failed the fillet. But, the user interface was messed up. It had taken me a quarter of an hour to get the UI panels to stay in place and remain visable. All that hard work was gone, and I wasn’t going to do it again! I uninstalled FreeCAD 1.0.2 and reinstalled FreeCAD .19. I didn’t expect it to draw the flywheel but it did, 6 spokes, fillets curved outer faces of the rim (inner and outer) and hub. I saved it many times to insure against crashes. It didn’t crash once. I even managed to “split” the flywheel in two as part of the process of producing both halves of a pattern for casting.

I’m dissapointed in the UI of 1.0.2, and I saw on the FreeCAD forum other complaints about the panels being difficult/impossible to position and keep visible. Maybe it will be fixed for the next release.

I think that the installation of 1.0.2 has messed up some of the display in .19. When installing 1.0.2 it did warn that this might happen.

This is the ver .19 flywheel with extended rim and hub faces to allow for machining after casting.

And the shaded flywheel.

The “dimples” in the spokes don’t appear in the STL file or 3D print.

Lee
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