twisted sweep

[Anonymous]

hello everyone reading,

I'm having some trouble with one particular shape, I basically want to achieve a sweep of a rectangle which is twisted along its length 180 degrees and curved along it's width with a spline or something, see the photos for details.

I know splines in general cause lots of issues and I've tried to avoid them as much as possible but for this I have no other choice.

I have looked for several solutions on youtube and some forums but couldn't find anything useful.

in the screenshot you see the splines i've sketched to reference the black face you can see in my sketchbook, which the face that should flip facing up at one point. the lighter grey coloured faces face down at one point in the twist.

Here's what I've tried so far: a sweep with a path and a (general) profile, in as well as the model and the sculpt workspace, lofts with lots of different rails I sketched in the same workspaces, I wanted to try just a form but realised it would take to much time and there would probably be a more precise way of doing things.

One thing I found peculiar is the fact that I couldn't do a loft form one rectangle placed at the beginning and one at the end of the spline using the spline as a guide rail, I think Fusion didn't or can't realise that the two rectangles were placed opposite from each other but turned with the correct edge touching the rail.

anyways,

Thank you for reading.

- Maarten

screenshots and sketchbook sketches:

top view (sketch)side view (sketch)tp corner view (sketch)top corner view (fusion)top view (fusion)side view (fusion)

[lichtzeichenanlage]

Can you share  or attach the project? Have you projected the connecting points from one sketch to the other?

[davebYYPCU]

You need a Sweep with Path and Guide Rail, 

I suggest the Path to be the centreline track, 

Then run a pipe or tube along it for construction, 

Guide rail must attach to the tube, for your design intent, then hide the tube.

I say this as Fusion was - there are new upgrades to sweeps with a twist function now, that I have not seen or tryied out, that may work for you.

Might help....

[Anonymous]

sure but its a big file so I'll just include the path and rectangles.

give me a second to reduce the file.

-Maarten

[davebYYPCU]

You need a Sweep with Path and Guide Rail, 

I suggest the Path to be the centreline track, 

Then run a pipe or tube along it for construction, 

Guide rail must attach to the tube, for your design intent, then hide the tube.

I say this as Fusion was - there are new upgrades to sweeps with a twist function now, that I have not seen or tryied out, that may work for you.

I also noted that your example appears to be a single line for the profile, and you would need to be in Patch area for that Loft.

Might help....

[Anonymous]

I had two rectangles attached at the base and where the line is visible In the screenshots i went too far back in the timeline sorry for that!

- Maarten

[jeff_strater]

Sweep with twist can help.  However, it distributes the twist along the whole length of the sweep, and it looks like this may not be the case in your model.  You can work around this, to some extent, by splitting the sweep into two parts - one without twist, and the second, where you do want the twist.  Alternatively, you can use Sweep with guide rail.  Since you already have a guide rail set up, this might be the way to go for this design.

Don't be afraid of splines, they work fine.  The tricks to remember for this usage are:  Make sure that the rail exactly intersects the profile.  I use the Sketch Project Intersect command to project the intersection of the profile into a new sketch that can be used to hold the rail curve.  Make sure that the rail curve is one spline curve - Fusion requires that the rail curve be tangent continuous along its length.  You can do this with more than one curve, as long as you have Tangent constraints between the segments.

The other recommendation, based on your images would be:  Use fewer fit points for both the path and the rail curve.  The fewer points you have, the smoother the result will be.

As soon as you share your cut-down file, I'm sure you will get lots of suggestions!

Jeff

[Anonymous]

here is an example file.

I know the file is kind of janky.

I had the thought of somehow making an offset in any way of the spline which will be offset along a certain radius of the original, so that you could move each point of the second spline around the first one, could this possibly solve the problem of the guide rail not working.

B.t.w. it's kind of late so I'll see you all tomorrow hopefully.

- Maarten

[lichtzeichenanlage]

@Anonymous: I'm new to F360. I've tested some things with your project and it looks like the sweep works out of the box and the patch -> loft needs some help. If you want to loft something and you want guide it, than all points must be connected. That could be done be various projection methods. I used the simplest one. You can find great screencast for those projection types and lofts here.

I took a screencast of my experiments. A bit bumpy, but everything should be clear.

[davebYYPCU]

Thanks for the file, my attempts at this were to confirm what Jeff said, the twist is full length of the path, with no other outside interference, (1st Pic)

I then attempted to separate the straight twist for 40% of the length of the path, then a Sweep with Guide Rail, for the next section, 

I would not be happy with the joint transition result, 

and to fix that would need a Loft with four 3d splines that remain - a consistent revolve - don't know the words for it, 

you will see I have constrained to be tangent the rail I made on the centreline, but you will need that sort of detail on the four rails, and beyond me at this stage.

File is attached, 

Were you intending the bar to move in Z direction, as was drawn. or did you also want the centreline of the bar to be parallel to the x axis? Currently it is not parallel.

Few things to think about, 

[davebYYPCU]

Here you go, the loft with tangent rails is much better in the transitional area, from straight sweep into the twist.

You need the middle profile to avoid the self intersecting nature of the design.

Tweak to suit your ideas, but still think the profiles should be parallel to x axis.

Might help....

[Anonymous]

Dear lichtzeichenanlage,

wow thank you so much for the effort of making a video about this!

It absolutely helps a lot.

I have tests it before in the patchwork space but it didn't work before for some reason, i don't know why though.

I've tried it again in the smaller file like you did and it worked great!

Thank you very much.

- Maarten

[lichtzeichenanlage]

It's not an effort, it's much more to learn F360 for me. It's all a take and give.

But you should definitely check the project from @davebYYPCU. Great work!

[Anonymous]

Dear Dave,

no I intended the bar not being parallel to the x-axis, It shouldn't be since my intention was you would be ables to se a sort of arc when you look at it from the YZ plane, it's more of a half arc so to say.

it was intentional for the end of the loft being moved over the z-axis.

- Maarten

[Anonymous]

yeah, I was just replying to that when you sent me the message,

still, thank you very much.

I'm still learning fusion360, and how to use every tool it's best potential, so now I know the power of loft and sweep, and it's biggest differences by your and dave's post!

- Maarten

[Anonymous]

This is exactly what I intended to do, and it looks great I will download you attached file to look at your steps in greater detail!

Thanks for taking the time to reply and learn me something.

I hope to one day be learning someone something like you learned me something just now.

Yours sincerely,

- Maarten