How do I curve a ridged object

[ianhughes7UFVF]

Hi

I have this ridged arm that I have created in Fusion.

Its for a B9 Lost in Space Robot.

I would like to curve it so that it looks more realistic. Like this:

I think this is something that probably is done in the Patch part of Fusion using a sweep, but I have no idea how to use that in this context.

Once again, any help would be greatly appreciated.

Regards

Ian

[TheCADWhisperer]

??? You marked this issue as "Solved" in this thread?

https://forums.autodesk.com/t5/fusion-360-design-validate/curving-a-ribbed-cylinder/m-p/8794042#M189...

Your first sketch is wayyy too complicated and too much work.

Pattern features rather than sketch elements and avoid necessarily repeated dimensions.

[ianhughes7UFVF]

Hi

I thought it was solved in the thread you posted. I thought it was clear before I actually tried it and then found I couldn't work out how to correctly do it after all.

I realize I did this the long way and using a pattern would be better, but I still could do with some clear direction on how to make this a curved piece?

Sorry to be a bother but I appreciate your help

Regards

Ian

[davebYYPCU]

You can’t make a straight part and then bend it, in Fusion, unless you use Sheet Metal tools.

your arm has to be modelled in the bent shape from the beginning.

To simulate the ribbing as well, the easiest method is a Sweep in the Sculpt area, similar to the other thread.

Might help....

[chrisplyler]

Sooooo... three months later you haven't tried the solutions in the other thread until now?

https://knowledge.autodesk.com/community/screencast/bcb3fa7e-411e-493d-a251-be7b0fc005e6

[ianhughes7UFVF]

Hi

😞

Every other question that I ask and is answered I test out straightaway before I accept the solution.

This one was one of those things that I thought looked straightforward and accepted the solution but then couldn't recreate it in my own project.

That was for creating a K9 Doctor Who Dog neck. Which I still need to do at some stage.

I am really sorry for that but I do try the answers shown. The screencasts are the best solve for me as I can follow it bit by bit.

I will try your screencast tonight when I get home and accept the solution after I have done it.

Kind Regards

Ian

[ianhughes7UFVF]

Hi

Success, well sort of. I created the curved part in a simular fashion to your screen cast, in metric, with the sizes I need.

It was a bit of trial and error getting it right. The only thing that is still problematic is the joins of each ridge, at the bottom:

This is going to be 3d printed so I need to know how to get those joins neat but also filleted.

The other thing is the insides needs to be a cylinder not the zig zag of the outside, like inside of the straight arm. That's probably a problem for later, but I am not sure how to introduce that, whether that  should have been part of the sketches.

Help is needed as usual.

Regards

Ian

[chrisplyler]

The way I got the seams to line up was as follows:

1. I made the arc 45deg.

2. I inserted the Plane-on-a-Paths at positions 1, 0.95 and 0.9. Those three planes represent a single rib. The rib will occupy 1/10th of that 45deg arc.

3. I made the Circular Pattern 45deg and quantity 11. Now, that will add an extra rib beyond the end of the arc, but defines the end of the 10th rib at the end of the arc properly. You can suppress that 11th rib instance if you like.

So the math has to work out such that the division are known and can be patterned accurately. If this is done properly, the edges of the ribs will line up perfectly. If not, well, you get something like your picture.

I'm surprised your brain hasn't figured out that if you want a smooth inside, the easiest way is to make it at the same time. Or instead, Sweep a circle along the arc either before or after you do the ribs. Although I must admit, I'm confused by this requirement. Real-life ribbed, flexible hoses and fittings and pipes and stuff like that don't have a smooth interior. If they did, it would defeat the purpose of the accordion design.

Screencast will be displayed here after you click Post.

437176e4-6e31-4dc2-b61c-72610720f535

https://knowledge.autodesk.com/community/screencast/437176e4-6e31-4dc2-b61c-72610720f535

[chrisplyler]

Also...

Filleting the peaks and/or valleys is not going to look right. If you want curves instead of sharp transitions, I suggest you change the loft profile conditions to Direction instead of Connected.

[chrisplyler]

Here I've set each profile to Direction instead of Connected, and set the Takeoff Weight of EACH profile (in each loft, so I did it four times) to 1.25 instead of 1.00. This gives a pretty natural looking result.

[davebYYPCU]

Good job @chrisplyler 

Just a reinforcing point, if the inside has a wall that is to be smooth, you could not accomplish with the same Loft as the outside. 

You will need to make the outside the same way with a solid Loft, then Sweep cut the inside hole out of it with a separate feature.

Fusion Loft can not do donut shaped / hollow Lofts in one go.

Might help.

[chrisplyler]

---

@davebYYPCU wrote:

Fusion Loft can not do donut shaped / hollow Lofts in one go.

---

Acknowledged. If you looked at thirty seconds of my vid, you would see that I used Surface>Loft for the exterior AND the interior, then patterned both at the same time.

I also mentioned the possibility of just Sweeping the interior.

[davebYYPCU]

My comment was not directed to you, we have to reply to someone,

but the future reading audience.

[ianhughes7UFVF]

Hi

The part is going to be a section of a B9 Lost in Space Robot 3d printed. So it will need to have a bit of strength to it as it will have a printed wrist and claw on the end. This is why I need the thickness to it and the inner tube tunnel to aid in the strength.

I am at work at the moment and I haven't got to a second look at the project. But what was getting me stuck is calculating the distance between the 3 planes for each rib. My drawing as yours has a 45 curve. There can only be 21 ridges in the arm as per the original prop and I fundamentally plan this to be straight then curved then straight again, so really probably on 7 ridges need that curve. So is there an equation that I can use to work out the distance between the 3 planes for the ridge, taking into account the 45 degree angle, the diameter of the circles for the ridge and the distance along the curve.

Sorry for being dense.

Kind Regards

Ian

[davebYYPCU]

T-spline on a spline curve, will save Chris pulling his hair out.

[davebYYPCU]

As mentioned. Will depend on material for what thickness or internal wall.  Have to be carful with the bend curvature of the spline.

[ianhughes7UFVF]

Hi

I will check out your work and follow the time line to see how its done.

I am really struggling with working out the correct distance to size to angle otherwise.

I will post my efforts later.

Thank you for taking the time as you all do.

Regards

Ian

[ianhughes7UFVF]

Hi

I have looked at your version of the arm and like the result as much as I like the previous version designed.

But I am stuck on both in regards to how to get the ridges right initially.

I would really like to know how to get the first method right. I carn't see how to correct what I have done to get the ridges to contact correctly. I realize its in the measurements between each plane, but I really want to know how to correctly calculate the distance.

Sorry to be persistant but when I work this out, there are so many other projects I can do.

I have attached the project again. Could you show me where I am going wrong in that and how to correctly adjust it?

Regards

Ian

[davebYYPCU · Accepted solution]

You will need to decide which bit to fix, seems like the pattern of 11 spaces, for 66 degrees, equals 6 degrees.

The second plane on a path is 5.865 degrees. It should be 6 degrees too?

You did not notice that your maths would have included the length of both lines?

You could change the pattern to 64.515 degrees but the thicken as it is, will overlap the other way.

I think you had two more problems that contributed, you did not stitch the two lofts together to make one body.

You then thickened them and the result was 1 body from two Patch bodies.  Patterning those by the overall angle error as above.

Pattern the surface bodies, and stitch them to one body, then thicken.  This workflow works as expected.

Still doesn't give the directional Loft as Chris demoed, but that is as desired.

Tsplines avoided all this.

Might help.....

[ianhughes7UFVF]

Hi

I am being specific with what I don't understand.

You mentioned that I need to make the angle 6 degrees. You have the edit feature, which only shows the distance as 0.398197. Is that meant to be related to the angle, and if so how do I interpret it. This is what has me stumped. I need the planes at specific angles, but I don't know how to put them there?

Regards

Ian