Loft issues/bugs?

[nunolimacarvalho]

Hi,

Still on my self-learning process of Fusion and recently have encountered several issues with the loft command that have been driving me nuts. While some issues clearly seem a bug, not sure about the others and that's why I am posting here for some help to clear up my frustration.

Attached is the f3d file with the basic sketch design and only 2 out of the 6 mov files I have made, which title correspond to the points below.

!! How can I send the other 4 mov files taking into account the limit of number and/or size of files to attach?

1. While on loft command (either new or edit) having the default guideline (even after changing its points position), when clicking on the cube it disappears, though it is still there and active as seen by the cursor icon and by clicking on it. Need to close and open Fusion to get it back again. [Not shown: It does not happen if the default guideline is changed to any other user defined guideline (rail or centreline) before using the cube.]

2. On a default guideline, which points position have been changed, after checking on Analysis tab different analysis types and leave None at the end, the default guideline goes back to its original position/points. When clicking in OK button still in Analysis tab, that change is taken into the design [Not shown 1: …but not if OK is clicked in Feature tab]. [Not shown 2: It reverts even in Edit Feature if same is done as mentioned]

3. Editing a loft feature (not new loft) with centreline, it shows Tangent Edges after going to Analysis tab and back to Feature tab.

4. To test 2 different rails have created two different lines on a sketch that go between the same points. On loft command, choosing any of those lines as a rail, for some reason it selects a closed profile and gives an error with that message. However, if 3 lines are created in the sketch between the same points, there is no problem and any of the 3 lines can be selected as a rail. [Not shown: Also, even having already one spline on one side and mirroring to that same side two additional splines (total 3 splines) the same issue appears but if mirroring 3 splines it doesn’t.]

5. Isocurve analysis on both rails and centreline lofts seems to be not working properly. Depending on the type and shape of the guidelines, some or all of the U or V curvature combs are missing as applying different number of isocurves [Not shown: in this particular design, only when choosing the straight lines (not the splines) of Sketch3 as rails on both sides, the curvatures combs (U and V) are shown properly regardless the number of isocurves]

6. Using symmetric rails or choosing a centreline, don’t understand why curvature combs of the isocurves are not symmetric on a fully symmetric solid as the one in this case. [Not shown: It is more clear at certain number of isocurves]

Hope it is clear and not wasting anyone's time

Thanks,

[davebYYPCU]

Create another message, add more movies.

1. Is an OS type error, unlikely to be anything to do with the Loft Tool try a different graphic driver.

2. Mapping Handles.  You are moving defaults.  
I presume more movies will show what happens using the rail sketch.

4. Untick Chain Select.

Might help…..

[nunolimacarvalho]

Realize I could send more attachments in the reply. So, here goes 3 and 4.

[nunolimacarvalho]

And 5 and 6

[davebYYPCU]

Mirrored splines are unreliable.  Use extruded helper body edges, instead.  Will improve the isocurves as a bonus.  Your getting into the realm of, model one quarter and mirror twice for the best result.

Might help…..

[nunolimacarvalho]

So, I'm not necessarily doing anything wrong and basically you confirm all these issues are as they are and I have to learn how to deal with them or go around them?

thanks

[davebYYPCU]

Check the result when using the body for rails.

Might help...

[TrippyLighting]

I can reproduce  2 & 3.  

I cannot reproduce 1. This vanishing view cube phenomenon has been reported a number of times in the past and is not limited to the loft tool. I believe it is hardware dependent.  

4. By default in the loft UI the chain selection is enabled. If you disable it, you'll be able to select the spline only and not the chain that forms between the spline and the line.

5. Your video is clear enough, and I've not looked into it.

6. The loft tool created NURBS surfaces and lacks a setting for internal symmetry. That statement assumes that this is technically possible within the geometric modeling kernel.

A different, more involved modeling

technique is needed to build truly symmetric loft geometry.

@Phil.E looks like there is some work to do in the loft UI 😉

[TrippyLighting]

Here is what I would describe as the most robust lofting technique in Fusion, providing you with the most control over the shape of the loft. It avoids using the twist control handles altogether.

[nunolimacarvalho]

Thanks for your answers and this body rails suggestion!

[nunolimacarvalho]

Thanks a lot @TrippyLighting  for all the trouble and your clear explanations on both videos and f3d file. It's good when finally I get the answers to these issues/bugs and move on. Following what @davebYYPCU  previously mentioned, I will definitely consider the loft on solids and mirroring as you also suggested and very kindly (and clearly) described on video. Very, very helpful!

Regarding the issue 1, I think you didn't actually reproduce what I mentioned but please correct me if I am wrong: while on loft tool, when you click on the view cube to change the view plane, it disappears. This happens only with default guideline and if you change to a rail or centreline, the view cube no longer disappears if you click on it. From your video it seems you never clicked on the view cube.

I have also tried it on Macbook Pro a little more recent than the one I use (still on MacOS Ventura), which had an updated MacOS Sequoia and a Apple M1 8 core graphic card, and the same happens.

Will you still have a look at issue 5?

Regards!

[TrippyLighting]

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@nunolimacarvalho wrote:

Regarding the issue 1, I think you didn't actually reproduce what I mentioned ...

---

In my screencast I didn't, but I've tested this over and over again with different workflows and my View cube does not disappear. Not on my home work station (AMD Ryzen 5950X, Nvidia RTX 3070ti, Windows 11), and not on my work notebook Dell Precision with Nvidia Quadro T2000 graphics, Windows 11.

However, I just tried it on my mid 2017 MacBook Pro (Ventura) and there the Viewcube does vanish!

 @Phil.E Ive seen this reported on newer macs in another thread just yesterday, so there appears to be a real macOS related issue!

Here is that thread.

I don't think there is a nee for me to reproduce #5. Your videos were quite self-explanatory!

[nunolimacarvalho]

Issue #1 - thanks again for confirming

Issue #5 - sorry but I didn't understand that's what you meant in your first message, which now I see was a kind of "yes, I got it and no need to check"

Issue #4 - I understand what you said that I need to disable the chain selection feature as the 2 lines end up making a chain, but when there is more than 2 lines, as I mentioned and showed, why it is no longer a chain and even with the chain selection enabled I can select any of the 3 lines? That has nothing to do with the loft tool and is something more fundamental do Fusion and 3D design that I am missing?

[TrippyLighting]

The chain selection can only work if only two lines/curves end in a vertex. If three or more curves end in the same point/vertex, the algorithm cannot (and should not) decide which path to take, to form a chain of connected items. 

[Phil.E]

Thanks for letting me know about the mac view cube issue.

Unfortunately, I don't have an hour to reproduce it. Can someone please point out which video and file attached to this post is useful for logging a defect? You all seem to know but I don't have time to catch up.

[TrippyLighting]

Will do in the evening!

[samuel.templeUCPAE]

Hey Folks,

If you can provide the File and a video for the issue, i will be more than happy to spend some time tomorrow (Thursday, UK) looking into. 

Thank you for raising this issue.

[TrippyLighting]

@samuel.templeUCPAE here is the video. The file is attached.

This was recorded on a 2017 MacBook Pro (Intel/AMD Radeon)

[nunolimacarvalho]

Got it! Thanks

[nunolimacarvalho]

Sorry @Phil.E and @samuel.templeUCPAE but came back to the computer only now and missed your request. Fortunately, and I thank you, @TrippyLighting already did it.