topic Re: Seeking advice on modelling approach. in Fusion Design, Validate & Document Forum

Seeking advice on modelling approach.

Anonymous — Sat, 28 Oct 2017 01:20:21 GMT

Hi,

I've been trying various methods (Sculpting and 2D Sketching -> 3D Lofting) to model the below flight control grip but have not been able to achieve a 'clean' model.

What is the best approach to modelling such as this ergonomic grip that has some very 'tight' geometry in certain places?

Thanks in advance,

Marc

Re: Seeking advice on modelling approach.

SaeedHamza — Sat, 28 Oct 2017 19:44:33 GMT

My approach would be a combination of the 3 designing environments, starting with the Sculpt environment and then getting the details done in the Patch or the Model environment

Do you have 2d view of it? ( top, side and front )

Regards

Re: Seeking advice on modelling approach.

beresfordromeo — Sat, 28 Oct 2017 21:23:54 GMT

hi @Anonymous

It would be good to look at what you do have. It could be that you are close enough to get a clean model with some subtle or not so subtle changes.

Whilst many will rightly use the sculpt environment for more organic shapes there are obviously real accuracy and parametric advantages to patch and model. For instance (in my amateur opinion) it is perfectly acceptable to use an unclean model as basis for a creating new profiles, using intersections, projections and splines etc. and lofting new curvature continuous surfaces.

If you are happy to share your existing files I would be really happy to take a look and see what I can come up with not least because it looks like a challenging shape to work on and those are the ones you learn most from.

Re: Seeking advice on modelling approach.

Anonymous — Sat, 28 Oct 2017 22:18:15 GMT

@SaeedHamza The best views I've been able to get are the ones I've compiled in to the image in my OP.

Because the grip is from a military jet that's currently in service I'd say any 2D drawings would be classified.

Re: Seeking advice on modelling approach.

Anonymous — Sat, 28 Oct 2017 22:21:15 GMT

@beresfordromeo

Here is what I was trying yesterday ... http://a360.co/2yYRYRa

As you can see the final loft at the top is messed up.

Re: Seeking advice on modelling approach.

daniel_lyall — Sun, 29 Oct 2017 06:21:46 GMT

If it's classified would you not get in the poop for posting the picks if so report your self to admin and ask for your post to be removed

Re: Seeking advice on modelling approach.

Anonymous — Sun, 29 Oct 2017 07:52:01 GMT

Hehehe ... it's not classified where you can't take photos. This is the flight control grip of the F35 Lighting, and there's lots of images on the internet, but to obtain specific "blueprints / dimensions" I would suspect to be classified.

Re: Seeking advice on modelling approach.

beresfordromeo — Sun, 29 Oct 2017 13:56:51 GMT

Thanks @Anonymous

I had a look at this model and I don't think it is a lost cause by any means.

The first thing to note is that your attempt at lofting is fine in principle but all of these (I think 15 in total) profiles are all connected rather than tangent or curvature continuous so the loft doesn't have very nice transitions between the profiles. This is where the patch environment is great, for getting continuity between profiles but you have to put in a little extra work.

Please note I don't have enough information about the design intent here to make a really nice model. If I did that you may end up with something that does not reflect what you want at all so I have kept your original geometry and made the best of it in the time available to demonstrate that patch is useful even when sculpt may technically be the right approach.

1. The first thing I did was to suppress features on the original loft at about 0.10.

2. At 0.17 you can see the first feature created which is an extrusion (Body 20) of the first profile with a taper angle of -10 degrees. This is to set up the next loft and manage the shape of the lower handle as you will see later.

3. At around 0.34 I have demonstrated another extrusion which will form the top of the lower handle part (Body 21)

4. So this is the important bit for controlling your lofts (especially in the absence of rails). At around 0.44 I have created a loft which is tangent to the surface bodies (Body 20 and 21)I created in steps 2 and 3. The tangency controls the shape of the loft, that is to say that the in order to maintain the tangency to the -10 degree taper (Body 20) in step 2 the loft has to curve (bulge) and taper back to the second extrusion (Body 21) created in step 3. If you wanted to change the nature of that bulge you could use the timeline to adjust the angle of the taper or change the tangency weight or both. Please note that this loft is performed between the edges of the surface bodies created in steps 2 and 3, not the profiles created by the sketches.

5. At around 0.55 I have lofted between the resultant body of step 3 (Body 21) and the next sketch profile (Sketch 35) to create (Body 23). This surface body is tangent to Body 21 but not obviously to Sketch 35.

6. Likewise at 1.06 I have used another loft between Body 23 and Sketch 40. Again using tangent with the Body 23 profile.

7. At 1.28 I have created another surface body using an extrusion (Body 25) from Sketch 42.

8. At 1. 36 you can see another tangent loft between Body 25 and Body 24. Also at around 1.48 the screencast shows how I am turning off sketches to use surface body edges as profiles and not sketch profiles. You probably get the idea by now.

9. At around 2.08. Well you get the idea another connected loft between profiles blah blah blah.

10. At 2.26, Another tangent loft this time between Body 25 and Body 27.

11. At around 2.47 I have created a sketch on the YZ plane, used Sketch > Project > Intersect to get the intersection points of your uppermost sketch (Sketch 52) to the plane and from there arbitrarily sketched a spline for the next step. Please note I didn't take much care over this spline because I don't know what the exact design intent is.

12. So the purpose of the previous step was to demonstrate (at around 3.00) that you can create a surface body using the patch command and an intersecting spline as an interior rail. It isn't really and elegant way of doing this in this model but it does demonstrate what you could do in this type of situation where you don't want a flat surface at the top of your form. If you took more time to create the sketch geometry for this surface it would naturally be better.

13. At around 3.30 I have demonstrated the last loft between the patch surface (Body 29) in step 12 and Body 27.

14. So the last steps were to (rather unnecessarily) reverse a normal and finally to stich the bodies together.

Ok so I hope that all makes sense. I am sorry that I can't spend longer on the videos or show you more techniques but sadly I am on a metered internet connection and these things all add up.

As I said the result is far from perfect but I don't know without more information what the design intent is. One thing is for certain that if you took the time to clean up the sketches for the upper part where the red destroy button is (Sketches 42, 44, 51, 52), you would get better results. There are limitless possibilities.

Another thing to note is that the sharper edges of the upper part would usually be cut from the lofted body. That is to say that that the lofted body would be a smooth organic shape and flats would be cut into it using extrusions or sweep or whatever is appropriate for making flat surfaces. I can demonstrate this in another video if that helps.

Re: Seeking advice on modelling approach.

Anonymous — Sun, 29 Oct 2017 19:11:40 GMT

Thanks for doing that @beresfordromeo really appreciate it.

I'll go over your steps when I get home from work.

Re: Seeking advice on modelling approach.

Anonymous — Sun, 29 Oct 2017 21:28:25 GMT

@beresfordromeo

Ha .... Turns out I can view the video at work (most sites are blocked here).

Again thanks for the video. I've viewed it and I can't wait to get home and actually go though it step by step.

In answer to your question, I'm an avid flight simulator buff and I'm building my own custom flight control system or HOTAS (Hands On Throttle And Stick) and rudder pedals.

I've got all the electronics side worked out so I'm now moving on to the actual building of the controls. I'm just starting out with CNC milling - just took delivery of a BF-LV20 and I'm currently converting it with all the CNC gear.

My ultimate aim is mill this grip (and other components) from aluminium - mill hollowed out halves of the grip is what I'm thinking at the moment.

Re: Seeking advice on modelling approach.

beresfordromeo — Mon, 30 Oct 2017 02:13:08 GMT

You are most welcome and thanks for the appreciation.

Hopefully if I get time and more bandwidth I can try to see if I can improve the result and record it for you. For sure it can be better.

It was an interesting question and sounds like an interesting project. Your question title was 'seeking advice on modelling approach and it is worth bearing in mind that to get your geometry cleaner still will most likely mean a combination of approaches. Hopefully other forum contributors will have other ideas.

Let me know how you get on.

Re: Seeking advice on modelling approach.

cekuhnen — Mon, 30 Oct 2017 02:20:53 GMT

@Anonymous

The result you posted at: http://a360.co/2yYRYRa shows the typical issue with doing this with a brute sketch surfacing approach.

Fusion is also not ideal (lack of tools) to do this type of work well just with surfaces.

While one could model the design with only profiles and surfacing tools the design is a call for T-Splines.

T-S will proceed particularly the rounded top much easier.

Thats the nice part about Fusion giving you 2.1 modeling options to choose from.

As a tip also look for elements that are added or removed. Build those as individual objects and then use the

solid combine to add or remove and fillet to smooth the resulting sharp edge.

Re: Seeking advice on modelling approach.

Anonymous — Mon, 30 Oct 2017 02:49:59 GMT

@cekuhnen

Thanks for the reply. When you say T-Splines are you specifically referring to using the 'Sculpt' environment toolset?

I have tried several times to create parts for the grip using sculpt object and even planes. I often start with a low poly cylinder or box and can get the right shapes, but I always end up with faces squeezed and pulled in all different directions when I try to add tighter details like ridges or smooth seams.

I guess the issue for me is when I move faces around I'd only like to move that face without altering the surrounding geometry, or the movement of surrounding geometry. Is there there a way to lock geometry (Vertices, Edges or Faces) while working?

Re: Seeking advice on modelling approach.

cekuhnen — Mon, 30 Oct 2017 02:54:33 GMT

@Anonymous

yes the sculpt mode

people say T Splines is easy but like NURBS it requires some practise.

the first model hardly is correct and requires modificarions

nice thing about TS is that it allows adding and removing of loopcuts while maintaining the original surface flow!

Re: Seeking advice on modelling approach.

beresfordromeo — Tue, 31 Oct 2017 21:59:31 GMT

I have been working on your model which is great because I have learned a lot from it.

I just wanted to show you and example of how I was able to get fairly clean geometry using again just the patch environment. I haven't recorded this in any detail or written out the steps involved but I will try and save some bandwidth now and post something when I get closest to something acceptable. If you get stuck with this again let me know. Hopefully someone else will have some better ideas using t-splines etc.

Re: Seeking advice on modelling approach.

Anonymous — Tue, 31 Oct 2017 22:18:29 GMT

Wow ... Nice work @beresfordromeo, that's a great result! Again appreciate you sharing your knowledge.

I've been actually playing around with the Sculpt tools using patch surfaces for the last couple of days, I think I'm getting the hang of it. The more I delve into it, the more I'm discovering new features / tools I can use.

I was just watching this video on the train this morning and I think this small feature holds 'a' key to making cleaner surfaces: Modify T-Spline bodies using tangent handles

Re: Seeking advice on modelling approach.

beresfordromeo — Wed, 01 Nov 2017 00:11:01 GMT

Hi @Anonymous

Thanks for the reply.

I had a look at that video. It is true understanding the handles helps a lot, just bear in mind that this is only edges that have this option (you have probably worked that out already).

I spent a lot of time on tspline trying to model this Karmann Ghia.

I had to give up in the end because it seemed that while a lot of things were much easier in the end you can end up going round and round in circles pulling here and there trying to get clean geometry. I decided there was something I was missing so went to the patch environment and found everything much easier. That is to say I found it took more work with sketches and tangent splines and planes all that stuff because you couldn't just pull around the geometry but the amount of time spent was the same or less.

I don't know if you have seen it but I really recommend this video for understanding t-spline workflow. It is really well made and makes a lot of sense.

https://www.youtube.com/watch?v=Gf1lNAGEalQ

Anyway, hope all goes well.

Re: Seeking advice on modelling approach.

Anonymous — Wed, 01 Nov 2017 01:38:55 GMT

@beresfordromeo

Thanks for video, I can't watch it now as YouTube is blocked at work, but just looking at the screenshot it looks like it fits with the type model I'm trying to produce.

Re: Seeking advice on modelling approach.

cekuhnen — Wed, 01 Nov 2017 01:51:05 GMT

@beresfordromeo @Anonymous

The mistake some make is to force a model into one way of modeling.

T-Splines and sub-d modeling in general has some advantages but also disadvantages.

The cool part about in Fusion is that you can mix them.

I use T-Splines more like a replacement of CV cage manipulation like in Alias Rhino since Fusion does not expose CVs on a BREP surface.

What's CV?

Anonymous — Wed, 01 Nov 2017 04:35:37 GMT

What's CV?