struggling with replacing a face

[Anonymous]

Hello, 

First, I should say I have only been using Fusion360 for a few days now, and have never attempted to use similar software before. I am basically clueless, but want to learn.

I am struggling to complete a design I would like to be able to carve on a CNC router. The end goal is a flag that appears to be flowing in the wind. I created the initial sketch with all the appropriate dimensions and extruded the flag as a simple rectangular box, and then worked on the stars so that they would be raised above the surface. That has worked for me.

My problem lies when I attempt to "Replace the Face" with a sculpted plane that I created. I like the look of the "waving" plane, but I cannot get the plane to replace the flat face on the flag itself. 

I attempted to replace the face on a simpler box with just three circles extruded into cylinders which stood proud of the surface of the box, with a similar waving plane in a separate job and it worked, however the extruded cylinders do not stand proud of the waving plane. Is this possible to accomplish? 

My end goal is to have the top surface of the flag having a smooth flowing contour with the extruded stars situated on top of the waving face, but also follow the contours. I also want small grooves in the waving face at the edges of each stripe and around the union and I'm not sure how to accomplish that either.

If someone could show or explain if this is possible and how to accomplish it, I would greatly appreciate it. I will attempt to upload the job here as well. Thank you for your time.

[hamid.sh.]

As far as I know what do want is more complicated than it can be achieved by Replace Face. Replace Face, in effect, extrudes source surface up to the target surface. There is also Emboss feature, but it can be used only for surfaces curved only in a single direction.

What you need, in true sense must be done by deforming the flat flag into a 3D flag. But Fusion 360 does not have a feature to deform BRep solids. You will need Mesh or T-Splines body for deformation.

I tried another workaround, which is not really correct but gives you "almost" what you want. Please see the attached file. I used a combination of Extrude and Split Body, and Chamfer. It looks like this (I haven't done chamfer for all stars, just a few of them for the proof of concept):

Because there always is an angle between local surface normal and extrusion angle (Z), starts are not perpendicular to the surface and chamfer makes this kind of unwanted result (peaks of stars are not sharp and there is a small surface at the root of each star):

When you want to chamfer all the stars you may have to adjust distances for each one individually, to get the best possible outcome (that's why I did only a few of them).

Again, this is not a real solution and doesn't make a clean 3D design, but I reckon it will be enough for making with CNC (though those tiny unwanted surfaces may cause problem, I am not sure). I hope it helps, but also hope someone else gives us a better solution here. I want to learn to do this better than I did.

[davebYYPCU]

Small grooves - please describe the profile, and or cutter you would be using, V groove, you can get with sketch lines on the wavy face.

Like @hamid.sh. I am still thinking on the stars, as your original has a yellow icon for taper angle, 

the easy bit is to unhook the stars from the base, when you extruded the base it is joined to the stars, and needs to be New Body.  Then the Replace Face works as expected.

I have bought the block and tspline forward in the time line, whilst I await the groove answer.

[davebYYPCU]

Can be done, a tedious exercise.

Couple of things, as you are new to Fusion kudos to you on managing so far.  Without being critical, will tell you how it was done, will send the file if needed - receiving your feedback on the grooves.

Your sketch 1 was so busy I replaced it.

For newbies, we recommend one sketch per feature, and fully constrained before it is finished.

The next sketch has the outline of the plate and the outline of the star region.

Next sketch was the 2d groove patterns.

My next sketch is a fully constrained symmetric star. (Not used) Needed for size settings later.

Then the 3d Sketch for the purple lines on the flag, Create sketch, Project to surface, select the lines in the 2d sketch and the face of the flag.

Last 3d sketch has the 48 star points.  Will make more sense shortly.

I then made a single star from my sketch to find the settings later

So having the replace face done, I then cut your Surface body down to flag region size. (Extrude > Intersect)

I then Created a Surface offset, 0.93 higher than the original, (Star Point height)

Using your stars, I selected the base face of each one, and with Extrude > Intersect, I cut the surface of the flag region, to supply 48 contoured bases of the stars.  Hide these plates.  

Making the last sketch, I created a 3d sketch, used Project to Surface, and vector projected each of your star points to the top surface.  48 Purple points.

Now you hide all your star bodies, and I replaced them with a Loft, from my curved base plate, to the purple point.  48 times.  These lofted stars are then Surface > Modify > Stitch to make 48 finished solid stars that conform to the flag shapes..

Solid > Modify > Combine selected the flag as target, and the 48 stars as tools. 

Sounds easy but was a little tedious, and I divided the lofts and stitching into batches.

Might help.....

[hamid.sh.]

Thank you @davebYYPCU! I followed and learned a lot from your approach. It makes really nice result. But I have a question:

Even though this method makes very clean shape and perfectly suitable for most purposes, still it's not exactly correct. By "correct" I mean if a physical flag was first flat and then became wavy, patterns on it (e.g. stars) would end up in [slightly] different shape and positions relative to what you achieve. This is because when you "Extrude > Intersect" extrusion is in Z direction, not perpendicular to the surface at every point. With small curvature that's fine, but with a surface that is curved a lot it deviates a lot from real situation. In simple words, this method makes stars that when viewed from top are equally spaced, but in reality distances (and shapes)  on a wavy flag will be slightly distorted. I put a decal on the surface to explain what I mean (I assume Decal fits the image on the surface, like a UV mapping, but I might be wrong):

Now my question; Was I right above? If so, I wonder if there is a way to do this perfectly? I can think of making an axis for each star point, Project to Surface a star sketch along that axis and use it to split surface, then use Loft... But that will be painstaking for 50 stars (and perhaps still not truly correct, because star points are projected along Z axis).

Again, I totally appreciate your method, just want to learn more and more. I may be too perfectionist. Also I might have been wrong.

[davebYYPCU]

Well, perfectionist or not, I was down a rabbit hole.  There was nothing evident in the file that you were after anything other than orthographic, (excepting the surface body for effect).

So now that you have the decal. I am with you - I believe it will map to the surface, at least you do have that effect in the picture. 

My first post had me in the thinking stage for exactly this preferred result,  but I came across a rectangle for the base of the flag, rectangles for the grooves and the pattern of stars were also rectangular so I took your lead.  Sorry about that.

Not insurmountable, edit the file so that, each of your star bodies are moved to match the top view of the decal, then the Extrude > Intersect and the top points will follow. Your choice if this is sufficient.  If not, then delete the top points, and Lofts.  New star points can be Projected to Surface with "Closest Point", and not "Vector", follow with new Lofts and stitching, etc.

No mention of the grooves?

Might help....

[hamid.sh.]

Wait 🙂 I am not the original poster. I just found your solution much better than mine, so I tried it and further ask the question. As such, @Anonymous should update you on grooves.

Anyway, thank you, I happily learned from you 🙂

[davebYYPCU]

Sorry, my reply was intended for the OP, not sure how I did that, my reply timed out near the end, and had to go again so maybe a bit quick to start again.

@Anonymous the grooves will benefit from the "Closest Point" projections as well.