topic Re: Bicycle Model Breaks When Changing Dimensions in Fusion Design, Validate & Document Forum

Bicycle Model Breaks When Changing Dimensions

dustindriver — Wed, 07 May 2025 16:48:17 GMT

Hello,

I've been working on a model of a cargo bike: https://a360.co/3SnIIgK

I have a base sketch that includes the base geometry of the bike. I can update the base geometry in the base sketch and most of the model will update. For instance, I can increase the length of the down tube and adjust the position of the central steerer tube and the frame model will update no problem. But the forks component will break.

I think I've done something wrong when I set up the forks. I drew them on a plane at an angle along the fork centerline. When I make changes to the base sketch, that plane remains stationary and the fork model breaks.

Any way to fix this, or will I just have to re-draw the forks?

Thanks!

Re: Bicycle Model Breaks When Changing Dimensions

TheCADWhisperer — Wed, 07 May 2025 16:53:15 GMT

@dustindriver

Can you File>Export your *.f3d or *.f3z file to your local drive and then Attach it here to a Reply?

Re: Bicycle Model Breaks When Changing Dimensions

TheCADWhisperer — Wed, 07 May 2025 16:56:38 GMT

@dustindriver wrote:
When I make changes to the base sketch, that plane remains stationary and the fork model breaks.

Any way to fix this, or will I just have to re-draw the forks?

You will have to create a new plane as a function of the base sketch and then redefine the fork sketch to that new plane.

This should be easy (if everything else was done correctly (unfortunately this is unlikely)).

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Wed, 07 May 2025 17:20:14 GMT

Thank you, I'll give this a try! Hopefully it's set up correctly, I followed the methods outlined in this bike frame tutorial: https://youtu.be/XemlmN-CWmM?si=FRe_T-o0gdc2emt0

But yes, I am unfortunately not formally trained. Yet.

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Wed, 07 May 2025 17:23:09 GMT

Here's the file, thanks! I truly appreciate your help. I'm having a blast learning Fusion 360, it's been a lot of fun.

Re: Bicycle Model Breaks When Changing Dimensions

TheCADWhisperer — Wed, 07 May 2025 17:40:11 GMT

@dustindriver wrote:
Hello,

When I make changes to the base sketch, that plane remains stationary and the fork model breaks.

Is the file that you Attached in condition BEFORE the model breaks as described or is it in the BROKEN condition?

Does Ctrl b (CMD b on Mac) return any unresolved issues highlighted in the Timeline?

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Wed, 07 May 2025 17:45:01 GMT

That is the model before it breaks. Here is the broken model. Thanks!

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Wed, 07 May 2025 18:02:52 GMT

I have a lot of errors, I think I should start a new file with a new base sketch and build it out from there. NBD, I have the base measurements so it'll just take some time to build the file correctly.

Re: Bicycle Model Breaks When Changing Dimensions

TrippyLighting — Thu, 08 May 2025 13:45:16 GMT

I ran a CTRL-B (Modify->Compute all) on the file that you sate is not broken.

When modifying a sketch, particularly when deleting and adding new sketch objects to a sketch earlier in the timeline, run a Compute all. That is your basic quality management of the model. If that returns no warnings or errors, then you can proceed.
Otherwise STOP, undo determine the root cause and fix it before continuing with modeling.

Also, routinely during modeling, check that your parameter changes actually work. Don't wait until the model is done! That makes it much easier to find and fix problems.

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Thu, 08 May 2025 16:46:31 GMT

Thanks for your help! I rebuilt the model, being very careful to label everything and create separate components for all the frame parts. Also made sure to project the base sketch geometry into all the parts. No errors now and the model updates as expected when I change the base sketch. Thanks for your help and for reviewing the file, I really appreciate it!

Re: Bicycle Model Breaks When Changing Dimensions

TheCADWhisperer — Thu, 08 May 2025 16:55:37 GMT

@dustindriver

You still have several sketches that are not fully defined.

I would even fully define the Construction lines.

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Thu, 08 May 2025 19:13:28 GMT

Ah, good catches! I used the Sketch.ShowUnderconstrained command to find the unconstrained points. Fixed them all. Still, the construction lines on the base sketch feel messy. Suggestions?

Re: Bicycle Model Breaks When Changing Dimensions

TheCADWhisperer — Thu, 08 May 2025 21:47:23 GMT

@dustindriver

I tried to post a more detailed answer, but for some reason the forum gave me an HTML error.

I will try again.

I would never use a meaningless 8 decimal place dimension in a sketch.

Instead add a logical Coincident Constraint...

Endpoint should turn from white to black after applying the appropriate constraints.

Re: Bicycle Model Breaks When Changing Dimensions

dustindriver — Fri, 09 May 2025 17:39:30 GMT

Thank you! That's embarrassing and I cleaned it up. Thanks again for all your help!