Need help with freeform modeling with point cloud as reference

[jonathan.westerlund]

Hey!

I having some issues with freeform modeling in Inventor Pro 2024. I have 3D-scanned a knob for a vintage car and the goal is to make an exact (or as close as possible) model of this knob so I can print it.

The shape seems simple enough, but I´ve found out that it is more complex than I thought... 

My plan was to use loft as much as possible, but it is hard to make the diffirent shapes blend together seamlessly.

Is there another way to attack this that is easier and better? Asking for some nudges in the right direction.

The model is attached. The link below should work to download the pointcloud.

https://www.dropbox.com/scl/fi/3vzfhz7ctbbpiqe5j78zg/Vred_PC-Cloud.rcs?rlkey=a0ijqctziigodj6msoy1g8f... 

The model is a mess, but you get the idea of my approach in this.

Thank you in advance!

Best regards,

Jonathan

[johnsonshiue]

Hi! I don't think you need to use Freeform workflows to create the geometry. You may use regular Part Modeling features to create the shape (a mushroom like Revolve, a symmetric cut from the top, and a few fillets to round off the edges). The resultant shape may not match the point cloud precisely (but point cloud isn't precise to begin with). The rest of the part can be created by using Revolve command.

Many thanks!

[jonathan.westerlund]

Thank you for the response!

Regular part modeling was my first go, but the result I got was not good. The knob has radiuses that intersect with eachother in multiple planes which makes the end result poor when modeling with sweep and revolve. 

[johnsonshiue]

Hi Jonathan,

There are multiple ways to create the egg shape. In this case, I use Revolve command to create a round surface. Solidify it by using Sculpt command. Mirror the body and round off the sharp edge. Lastly, use Direct Edit -> Non-Uniform Scale to deform the shape. The resultant geometry is as smooth as it can be.

Typically, I would use traditional modeling commands like Revolve or Sweep, before resorting to Loft, Freeform, or Boundary Patch. The reason is simple. The geometry created by those traditional modeling commands is like a universal recipe. If you apply the same geometry input and use the same command in another mechanical tool, the result will be the same. Just as you follow the recipe and use the same ingredients, you will get the same dish. While Loft, Freeform, or Boundary Patch rely on proprietary algorithm native to the CAD tool, the shape may not be replicable elsewhere. Please take a look at the attached file.

Many thanks!

[lauri_barnhart]

Hello, @jonathan.westerlund,

Just checking in—did the responses shared by @johnsonshiue help clarify your question?

If so, please consider clicking the "Accept Solution" button. Doing so helps others in the community find answers to similar issues.

If your question still needs more attention, feel free to reply here with an update. This way, other members can jump in with further suggestions or guidance to help you move forward.

All the best,

Lauri | Community Manager

[sjowe]

Thank you for the response! I looked at the file and I fully understand what you mean and way to model it using ordinary modeling techniques. But I am not fully satisfied with the difference between the pointcloud and the model. See attached image.

I have some ideas now that I will try and post in this thread shortly. Thank you all for the answers to my question so far! Stay tuned for the end result.

Best regards, J