How curve edge and how fit to surface

[jonniepickering]

Hi folks,

A couple of questions please.

I have created this sculpture of a spoiler extension for a car. I have created one half so it can be mirrored.

I want to please create curved edges please, the back edge should be fully curved and the front edges that attach to the existing wing should just curve down to the surface (90 deg)

Two pictures below and full export attached.

Thanks

Also one other question

How do I cut away the unwanted material from the inside of the model so it fits the rear of the existing wing.

Many thanks

[TrippyLighting]

I thought we've covered this already in two previous threads?

Let me ask this again. How were the original surfaces created?

I mean the geometry before you start adding your extension.

Is there a reason you are working with a disabled timeline?

[jonniepickering]

This is a different model from previous attempts..

Somebody told me I should disable the timeline as it causes problems.

Is what I am asking too difficult or not possible or is there another reason why you aren't able to give me a straight answer to these questions?

Thanks

[jonniepickering]

I don't know how the original surfaces were created by the way, they were done for me by somebody else, but now I am trying importing the original .stl scan data and then am going to try and map to that surface...

I will keep trying on my own and using YouTube I guess, I was thinking this would be a good source of help but currently I don't seem to be getting far..

[TrippyLighting]

What you are attempting might well be impossible and can be very difficult.

If you really had the experience to create such models, you'd not have asked the question you did and your models would look different.

You have not answered my question either and the reason why I am asking it I have explained already in the previous threads.

Trimming and stitching T-Spline based NURBS geometry with other T-PSine based NURBS geometry and can leave terrible surface and curvature artifacts and that can inhibit your ability to model what you want.

IF the original Wing was modeled as a T-spline then it is easier to modify that original model, but NOT as a separate T-spline as surface transitions will not be smooth.

[TrippyLighting]

This is a good source of help if you answer questions and follow advice. Can you post that scan data (.stl file) ?

That would indeed be very helpful!

[jonniepickering]

It's a shame but I have decided to find a different forum to get help.

I am only learning and you only seek to mock what I feel are great attempts for somebody who has zero experience with this tool and is trying very hard to teach myself something...as you say is very difficult to achieve.

Usually I get great help on forums but you have just been quick rude and speaking to me like I'm an idiot. I'm not an idiot, just not as experienced as you...

[TrippyLighting]

I don't really know how you expect to be helped if you don't answer questions!

Also, I did not mock you. 

I simply explained that the techniques you are using have pitfalls and the reason I asked the questions was to see if we can explore a different and better way to get you to an end result. 

[jonniepickering]

I am feeling very frustrated, as you probably tell... I'm trying lots of different techniques and each time I try something new, I think I learn more, but ultimately, I just need somebody to tell me what the correct process ought to be..

I know that's probably not something that can be taught in one post on here, but I'm trying to ask the questions I think I need, if you feeling I'm going down the wrong path or asking the wrong things, please could you jsut tell me what process would be best here.

I have the .stl (attached), I can learn quickly any process I'm told, even if I'm pointed in the right direction, I can go away and learn a technique..

Please, if you could jsut give me the high level steps that I should follow in order to achieve the desired result which is this...

I have a 3D scan .stl

I simply wish to create aero parts that can fit snuggly onto the surfaces that have been scanned.

Once I have built the model in Fusion, I will then have these CNC'd or 3D printed and a mould taken.

I have posted pictures which hopefully shows what I'm aiming to achieve.

I'm sorry if I was frustrated with your comments yesterday, I'm just really trying and need some guidance.

If we could start form the 3D scan and just tell me what steps I should take from there I'd be very much apreciative.

Kindest.

[TrippyLighting]

---

@jonniepickering wrote:

I have a 3D scan .stl

I simply wish to create aero parts that can fit snuggly onto the surfaces that have been scanned.

Once I have built the model in Fusion, I will then have these CNC'd or 3D printed and a mould taken.

---

Aha! I had a feeling that is what you want to do but wasn't sure.

You made a statement in your initial post I don't fully understand :

"the back edge should be fully curved and the front edges that attach to the existing wing should just curve down to the surface (90 deg)"

I am assuming that means that you want the surfaces in the area lined in red to blend perfectly smoothly and also for the rear edge of the existing spoiler to transition smoothly into the rear edge of the extension as I try to indicate with the green line.

From a modeling standpoint that can be done albeit isn't necessarily simple.

However, from a manufacturing standpoint, in order to blend perfectly between surfaces that will require some application of Bondo, sanding, and re-painting. When you 3D print this, or CNC machine this you'll end up with some minimal material thickness. Also when gluing this onto the existing piece you'll have to assume some bond gap to be taken by the adhesive. That will result in some form of a lip.

Can you explain what your expectations are in terms of the finished end product and what you had planned in terms of attaching the 3D printed or CNC machined piece to the existing part?

The reason I am asking this is that we can, of course,  try to create perfect blends in CAD, but in the end but might end up spending time on perfecting CAD geometry that you won't be able to exactly replicate with retrofit manufacturing methods.

As such, the T-Spline geometry you have in the model might serve as a good start.

[jonniepickering]

Hi,

Actually no, I do not want to blend them.

The shape I have shown above is almost complete exactly as it looks. 

My wing extension is simply going to sit on the rear of the existing part. and I have aligned the edges how I want them already.

See in the pictures below you can see I have already made a 2mm allowance for strength in thin areas but I wish to create a smooth fillet on the front edge and you can see I've already created a the round edge on the rear by segmenting the rear surface and then pulling the points out to make the shape I want.

You're right also about allowing for the adhesive and actually I will be using 3M double sided adhesive for automotive parts which is 1mm thick, will will make a trench for this on the under side, once I have managed to get the inside surface cut out correctly.

I guess the main question for me here is, how to do I get that cutout of my model to accurately fit the existing body part. From there, I guess I can then remove any additional material for the adhesive tape etc.

Many thanks

[TrippyLighting]

So there are a few things:

1. Your extension is comprised of three separate T-Spline bodies. This should be one body.
2. You somewhat shelled it, but hat is too early! If shelling - creating a hollow structure - is really what you want to do, then that should be close to the last step in the process and preferably nor be done as a T-Spline.
3. If you want to use the existing surface to trim away from the T-Spine, the T-PLSine needs to be converted manually to a Surface, or solid body. With the timeline enabled that conversion happens automatically when you click on "Finish form" however, in direct-modeling mode, that needs to be done manually.

I've given the topology of your T-Spine a little TLC and applied symmetry then converted it to a solid body and then shelled it for clarity.

The red arrow and question mark are to ask whether that is the edge you wanted to round over?

The Cyan line indicates one of the problems. ON the top, you can see that that red surface clearly intersects the blue part, so in that area, the existing surface body can be used to trim the blue part.
However, on the bottom that isn't the case.

You would either need to create a surface as indicated by the cyan line, or you need to retract the blue body/surface into an area where you do have a surface.

[TrippyLighting]

So, in essence, this is what you're after?

[chrisplyler]

@TrippyLighting  was not mocking you.

He is one of the very best at Fusion on this forum. He is, even more importantly, also has some of the best qualities of a great teacher, who tries to figure out the level of the student and them address issues appropriately. He wasn't trying to mock you at all. He was trying to figure out how best to guide you. If you listen to him, you will not just get a list of four main steps. Instead, you will get the steps AND and a good understanding of why they work the way they do. Only a tiny percentage of teachers can give that to their student, in any subject.

[jonniepickering]

Yes yes yes!!...that looks amazing!!!

Are you able to share the steps of how you got there so I can try?

Many thanks, and sorry for my reaction yesterday...partly frustration and partly as I'm locked in my house with two crazy kids...and wife...

[TrippyLighting]

 I'll try to create a screencast later tonight. It would create too wordy of a written reply and my typing speed is pretty terrible.

Edit:

I have attached the model

[jonniepickering]

Amazing thank you!

[TrippyLighting]

Here is part 1 - clean up 😉

1. Delete all the interior "walls"

2. Join the 3 separate T-Spline bodies.

3. Clean topology 

[jonniepickering]

So awesome, thanks! I see when I used the thicken tool it created a second shell and then that has caused all kinds of crazy geometric  things inside..

I will crack on with this and look forward to seeing the remainder of the process.

Many, many thanks!!

[jonniepickering]

UPDATE: OK, I've done this now..

You have no idea how much this is helping...after weeks of trial and error, this is real progress with this...

I'm now up to where you have shown me on your video

😄