Extruding along normals / multiple faces

[sis_gnougnou]

Hello everyone,

I'm trying to make a small trench across multiples faces, with the same exact depth all along. Here is an example done in Cinema 4D, where I achieved this result really easily using one bevel and one extrude along normals :

For now, I tried 2 solutions. The first one, which is my last resort, is extruding from a plane all the way through my entire body. The issue is that it doesn't follow the normals. As a result, faces with more extreme angles will have longer edges. Also, and more importantly, it is impossible to do small pits, since the body is cut on its whole thickness :

One other solution I tried comes from this thread : https://forums.autodesk.com/t5/fusion-360-design-validate/extrusion-problem-extrude-along-face-norma..., But the geometry went all weird :

I attached the Fusion file. I'm going to do a lot of those trenches, by the way. Any easy solution is more than welcome 😄

Thanks and have a nice day !

[YoavFriedlander]

You can use the emboss tool like a boss ! 🙂 select faces you'd like the channels - then select sketch profiles (you can select multiple) and use the emboss tool from the create menu - it will be very close ! 🙂 

[sis_gnougnou]

Thanks for your help.

I indeed tried this yesterday but the geometry would break if I digged too much. This is clearly what I need, but as soon as lines are not straight across multiple faces, every tool break so far.

I'm actually really surprised how "hard" this task is on Fusion360. I was expecting more people to need something similar. I mean isn't there a way to "drill" along the split face lines while following the faces normal ? That would be insane for a software like fusion not to include this feature, while being so trivial on any freeform modelling software.

[YoavFriedlander]

@sis_gnougnou  sooooooo... After trying everything my brain can come up with - including creating flat surface bodies cutting them nicely with the sketch - folding them into place - since sheet metal can't handle 0 bend radius - and trying to give them thickness and failed completely. I went with a nuclear way:

I made a flange using the side profile of your shape. It came wide radi that you would want to avoid obviously - I unfolded it and extruded the sketch half way into the sheet metal body. Then refold faces - made a derive of the sheet metal body turned off the history on the new file and had a solid body. I deleted and round face and remained with a hybrid 🙂  it has the curved solve connecting the folded face extruded pattern with sharp edges... It is not perfect or mathematically correct but might be helpful or of interest! 🙂 

What I noticed when worked manually is that there is no straight - proper - way to execute the following normals because they end in different vectors! - the software will have to determine points at which the faces make translation - I wonder how truly "simply flat" the results are in Blender or other Cinema 4D - I suspect there is more to it than we might think - but maybe you can find samples in Solidworks or other BREP software to compare with handling with such problem ! - SUPER INTERESTING SUBJECT!!!

  

[jhackney1972]

At least in this model, the Emboss command seems to work if I "Redefine" your cutting profile to the backside of the model.   Model is attached.

[sis_gnougnou]

Someone's been busy ! 😄 I thought of the flat surface as well, but as you mentioned, there is no proper way to set the radius to 0, shame.

C4D, Blender & Co may not always give a perfect result, but you can always fix the geo easily by moving vertices here and there until it's good enough. But that's the issue, I don't want "good enough", hence why I'm on fusion. I have hard surface modelling to do and I don't want to bother with topology.

Could you give me the file so I can see/test what you did ? I'm not familiar with metal sheet. Thanks a lot for taking the time to help me 🙂

[sis_gnougnou]

Hello, thanks for helping me.

It indeed work. Sadly, I do need it on the other side. I think I will end up keeping straight lines when going across 2 surfaces, since non "flat" angles are what's causing all those issues...