topic Re: Creating Shell of Complex Lofted Shape in Fusion Design, Validate & Document Forum

Creating Shell of Complex Lofted Shape

colemanHEXZG — Tue, 11 Feb 2025 20:56:48 GMT

Hey there! I'm trying to figure out a way to create a shell with a thickness of 1mm and a clearance within it, so the shell can fit over the body that the mesh is created using. I would ideally love to just scale the body to grow uniformly by 1mm and then just use the shell command, however the shell command is failing when I try and use it. I also have tried to copy the body and then scale the exterior body and do a Boolean subtract using the smaller body, however the scale command isn't scaling uniformly from the center to allow me to easily do that (some parts are thicker than others).

Is there a better workflow I should be doing to fix this or something I'm missing?

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Wed, 12 Feb 2025 01:07:44 GMT

@colemanHEXZG

Are there any issues highlighted in yellow or red in the Timelne?

This is a pretty rough model - I would be surprised if it DID shell.

Stop and ask questions at the first sign of trouble. This will take some time to diagnose.

Edit:

First thing I would have done is place the import with symmetry about the Origin.

Sketch1 is very very rough. Already building a house of cards on a foundation of quicksand.

Use lines and arcs if possible (fully dimensioned and constrained) rather than splines.

Certainly, don't use multiple splines where a single two-point spline will suffice.

What is this number?

Most designs exhibit significant symmetry.

I do not see symmetry in your Sketch1?

Re: Creating Shell of Complex Lofted Shape

Drewpan — Wed, 12 Feb 2025 01:14:32 GMT

Hi,

I find the easiest way to create a shell is to use the Surface commands.

The easiest way to do this would be to create the shell with the Offset command

and use the surface of the object as your body to get the initial 1mm Offset,

And then use the Thicken tool to create the 1mm thick new surface.

I have created a simple cube as my original body and created a shape that

is 1mm from the cube and 1mm thick.

Cheers

Andrew

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Wed, 12 Feb 2025 01:34:33 GMT

@Drewpan wrote:
Hi,

I find the easiest way to create a shell is to use the Surface commands.

The easiest way to create a shell is to use the Shell command.

Can you demonstrate your technique using @colemanHEXZG model?

Re: Creating Shell of Complex Lofted Shape

colemanHEXZG — Wed, 12 Feb 2025 14:08:10 GMT

Thanks for the insight @TheCADWhisperer. Truly I will admit I could do a better job on the symmetry of the model which I will work on and try re-uploading. However, the main complexity of this is due to not having the physical model that the mesh is created from, so I have no measurements to compare against. I can make it symmetrical, however, up to this point I have gotten as far as I have, from a fitment basis, through trial and error. Once I move everything to the origin I am hoping it might give me a line to create symmetry over.

On a side note, I was also going to experiment with the offset tool in the sketch workflow and see if I could offset the sketches by enough to do a second loft and then the same negative boolean.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Wed, 12 Feb 2025 16:07:31 GMT

@colemanHEXZG

Most designers use easily measurable dimensions for aid in quality control inspection (and manufacturability if mass produced), so although you only have a scan and not the actual model you can infer many/most of the dimensions by observation and logic. This one will be a little more complex because of the geometry, but it is not freeform geometry, so you have a reasonable shot. It won't be all freehand art. But I would expect someone to have considerable experience before taking on a project such as this. You should have been completely unsatisfied by your initial attempt.

Unfortunately, I don't think you have gotten good guidance in your previous interactions in this forum (not just this thead).

Re: Creating Shell of Complex Lofted Shape

johnsonshiue — Wed, 12 Feb 2025 17:37:06 GMT

Hi! Since this is a mesh model to begin with, you may use Mesh Design environment to edit the mesh. You may use the Shell command in Mesh Design to create the hollowed mesh.

Many thanks!

Re: Creating Shell of Complex Lofted Shape

colemanHEXZG — Wed, 12 Feb 2025 22:30:04 GMT

I sadly cannot use the mesh design environment due to this part eventually going into production. This project was given to me before it was realized how complex it was so I am ultimately out of luck and going to just have to do my best.

I've uploaded the model as it stands now after spending the day reworking it. I don't believe that it is perfect at all but a lot better than it was... Currently, I am having issues with getting the edges to line up correctly. Are there any suggestions for this?

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 00:54:27 GMT

@colemanHEXZG

This is still very very rough and illogical.

I am hesitant to take this on as this could take quite some time to guide a beginner - but are you willing to start from scratch with instruction (might take a month or two at free guidance)?

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 13:40:54 GMT

@colemanHEXZG wrote:

I've uploaded the model as it stands now

My first thought is why did you scale the import?

This moved it away from the Origin.

I suspect that you had the incorrect units set on import.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 13:54:24 GMT

@colemanHEXZG

Let's start with your sketch labeled Sketch2.

You should probably forget about Mesh Section for now - it is not useful with this scan data.

Blue lines should keep you awake at night. STOP on any sketch that has blue lines. Do not continue. Ask questions.

I see a lot of Mirror (or Symmetry Constraints). There is almost always a more computationally efficient technique.

I see an inside and outside offset sketch geometry - not needed. Keep sketches simple. Probably don't even want the Filets in the sketch, but for now we will leave them in.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 13:57:15 GMT

@colemanHEXZG

This dimension is impossible to measure in the real world and therefore does not make logical sense.

Re: Creating Shell of Complex Lofted Shape

colemanHEXZG — Thu, 13 Feb 2025 14:07:29 GMT

Yes, there was an issue with import, and I can start over if needed and use the correct units. The main questions I have are pertaining to that I don't have the object to measure and the edges are all filleted at an unknown amount.

I can wait to fillet the edges after if that would give better results though.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 14:12:03 GMT

@colemanHEXZG

When I add the missing dimensions - none of them make logical sense. Not one!

Note that when the sketch is fully defined with dimensions and logical geometry constraints that it turns from blue to black.

It might seem like a lot of extra work, but actually, when done properly - Fusion does all but one of the geometry constraints for you.

The only thing you need to do is enter logical dimensions.

Note: It should not escape your notice that you have not been offered this logical information by the experts here in ANY of the previous responses to your queries.

I quite frankly can't understand that omittance.

Maybe it was a lack of information in the original problem descriptions.

My initial impression is that this is a scan of a commercial product.
I know that you stated that you only have access to the scan, not the physical model from which it was made, but can you identify this product?

Some photos of the actual product somewhere on the internet?

Photos along with the provided scan would go a long way towards making this reverse-engineer easier.

Re: Creating Shell of Complex Lofted Shape

colemanHEXZG — Thu, 13 Feb 2025 14:18:10 GMT

I appreciate the insight. I can most definitely try and use more meaningful thought behind my dimensioning, or lack of. My initial thought process was due to not having an object to measure, I shouldn't create dimensions that couldn't be confirmed. I can gain photos if required, however, are photos going to not be the same situation as the mesh since it is difficult to measure distances on that as well without a scaling point to confirm what the sizes are supposed to be?

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 14:27:14 GMT

@colemanHEXZG

I don't need exact dimensions - because I can easily edit dimensions if I have entered them in the sketch. That is the point of parametric history-based modeling. If I don't have dimensions or I don't have logical geometry constraints - it all falls apart on editing. And I never get everything right on the first attempt, I always have to edit the design.

Otherwise, it is all freehand art dependent on artistic skill. I am not an artist. In 30 years of teaching, I had maybe two students that I would call professional level artists. My experience has all been in the realm of measurable/reproducible geometry for mass production.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 14:47:11 GMT

@colemanHEXZG

In Sketch2 you have an arc that is very very close to being a straight line.

Now if you intend for an arc, that is fine, but it is so close to being a line that I have to wonder about the true Design Intent?

Highlighted blue at the bottom. 0.04 mm from being straight line.

Re: Creating Shell of Complex Lofted Shape

colemanHEXZG — Thu, 13 Feb 2025 14:47:59 GMT

@TheCADWhisperer

Thank you for the insight. Are there any better resources or mentors to learn about this from a foundational perspective? I took a CAD design course in college, but it was very surface-level and did not give me many tools to tackle stuff like this outside of very basic shapes.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 15:09:49 GMT

@colemanHEXZG

I assume you don't want to go back to college (but I could recommend a good program).

It would have been best to build up your skillset in Fusion from simpler geometry, but here we are.

Ask your questions here and insist on good answers. But go step-by-step, not create a bunch of difficult to correct geometry and then ask questions after it is all created.

For Example:

Question 1. How do I import scanned geometry and get to correct scale.

Provide the forum with the original scan file (not the *.f3d file) and indicate approximate Design Intent size.

Wait for answer and then implement the technique given.

Question 2. Here is my first sketch. Can the experts here take a look at the sketch and make recommendations?

...and so on, to the completion of the project.

Re: Creating Shell of Complex Lofted Shape

TheCADWhisperer — Thu, 13 Feb 2025 15:12:17 GMT

@TheCADWhisperer wrote:

Ask your questions here and insist on good answers.

@colemanHEXZG

If someone suggests using some technique - ask them to demonstrate the technique using your geometry.