topic Betreff: Loft Command Problem in Fusion Design, Validate & Document Forum

Loft Command Problem

oldtbone55 — Wed, 30 Jan 2019 15:50:39 GMT

Hello fellow users,

I'm running into an issue when I try to use the loft command to join several circle sketches that are at different heights in order to create a smooth recess on a guitar body where the control knobs will go. It worked for two of the controls but I can't get it to work for the other two. It doesn't seem to like the fact that the circle sketches for these two particular controls are intersecting some of the body contour lines. I used the project to surface command to project the circle sketches to the body. I've attached my fusion file for your reference as well as a screen shot with the error.

Thanks for your help.

Cheers!

Betreff: Loft Command Problem

g-andresen — Wed, 30 Jan 2019 16:48:40 GMT

Hi Tony,

there´s just an empty file

günther

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oldtbone55 — Wed, 30 Jan 2019 19:17:17 GMT

Hi, I opened the file and it wasn't empty. I've attached it here again.

Thanks.

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davebYYPCU — Wed, 30 Jan 2019 23:15:07 GMT

File is empty at my end...

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oldtbone55 — Thu, 31 Jan 2019 01:08:17 GMT

That's really strange. I've attached another file in a different format.

Thanks.

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jeff_strater — Thu, 31 Jan 2019 01:42:45 GMT

@oldtbone55 , the PNG file is fine, it is the .f3d file that is empty. Can you try sharing that one again? Thanks.

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oldtbone55 — Thu, 31 Jan 2019 02:07:59 GMT

Sorry about that. Here's the f3d file again.

Thanks.

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jeff_strater — Thu, 31 Jan 2019 03:53:26 GMT

@oldtbone55 , thanks for the design. The problem seems to be with the sketch curves for these profiles. How did you create them? I was able to fix one by adding missing coincident constraints between some of the curves in each profile. However, that did not work for the 4th one - those constraints can not be added. It looks like for some of the ones that succeeded, the curves are single circles, but for the ones that fail, they are composed of two or three curves, which are not properly connected.

I would recommend re-creating those sets of curves, using connected curves, and if possible, single circles as in the ones that succeeded. In the screencast below, I show just copy/pasting one of the sets that work. I suspect that you had other reasons for making these all be individual sets of profiles, but you might be better off just re-using the ones that work, or re-creating these.

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davebYYPCU — Thu, 31 Jan 2019 04:03:24 GMT

@jeff_strater took the wind out of my sail, he has said, what I was going to.

Would you be better to make a cutter body to Combine Cut the cavities, rather than fiddle with 3d sketch non coincident points?

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oldtbone55 — Thu, 31 Jan 2019 04:25:33 GMT

Hi Jeff,

Thanks kindly for your screencast. The original body was done in Solidworks so does that mean I would have to change the sketch curves by going back into solid works? The reason I created 4 different sketches is that the contours are different in each position on the body where I projected my sketches. If I copy and paste a working one into place as you did, the contours won't be correct for that part of the body. Is this a valid assumption or will the copied sketch conform to the contours of the new position? Also, my version of Fusion doesn't have the Design mode so I wouldn't be able to fix any of the sketches as you did. Is the Design mode part of a different version of Fusion?

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jeff_strater — Thu, 31 Jan 2019 04:33:45 GMT

I don't think that Fusion imports sketch curves from Solidworks, so I think those curves were created in Fusion. So, you should be able to do this in Fusion, not Solidworks.

You can use Project Sketch to Surface to get the curves to map to the surface, though you should only need to do that for the top-most curve, right? You can also over-build the surfaces, so they extend beyond the body.

the reason why my screencast has "Design" is that I have the "UI preview" turned on (you can do this from the Preferences dialog). It's just a different organization of the same set of tools that used to be in the Model, Patch, Sculpt, and other workspaces.

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oldtbone55 — Thu, 31 Jan 2019 05:21:49 GMT

Hi There and thank you for your reply. I wonder if you could explain on your recommendation. I'm not understanding what you are proposing and would like to understand it.

Thanks Again.

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oldtbone55 — Thu, 31 Jan 2019 05:29:29 GMT

Hey Jeff, thanks again for your help. I'm trying to figure out how I can remove or change the body lines in Fusion. I've tried to remove them but it's not working even though they highlight in blue when I click on them. Funny thing is that when I click on the body all of the lines disappear and the body looks like a proper solid. Can you help me with this?

Also, each of the recesses for the volume and tone controls have to follow the body contours so I projected each of the sketches I created to the body surface and then moved each ring down different levels so I would get the proper recess when I did the loft. I don't think I can use just one sketch for all for locations but maybe I'm understanding what you're getting at.

Thanks Again.

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jeff_strater — Fri, 01 Feb 2019 01:48:56 GMT

sorry for the delay, there was sleep and day job in between...

Basically, what I think you've found is a bug in Fusion. I'll log that and get it looked at. I tried a bunch of stuff, and finally, what I would to is to just model one of these cutouts, and then copy/paste it into position for each know cutout. I don't know if that will be satisfactory, but you can always tweak the results to get what you are looking for, I think.

[edit] the loft/project curve to surface bug has been logged as FUS-46710

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oldtbone55 — Fri, 01 Feb 2019 04:14:45 GMT

Hi Jeff,

Sincerely appreciate the help. Funny, I just the last couple of hours with
a friend going over the file trying to figure a work around. He's the one
who created the model in Solidworks and he's quite familiar with Fusion.
His conclusion also was that there's a bug in Fusion. We approached it
several different ways but to no avail. He'd have to bring the model back
into Solidworks to fix it.

If I could bring the model into the t-spline environment and attach
t-splines to the surfaces then I could turn it into B-rep and then a solid
body.

Thanks so much for your help. I hope you were able to get a good sleep.

Tony

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TrippyLighting — Fri, 01 Feb 2019 17:25:32 GMT

I've looked at the model and find that it exhibits quite an unorganized hack/slash technique. Components are being moved when not necessary. Sketches are not in the components that belong into and are not properly constrained and dimensioned etc.

Projecting sketches onto surfaces is for the most part is not a good technique. The surface can be directly split with split face and the unneeded faces can be deleted. In general these edges, instead of sketches should be used for lofting. Splitting a compound curved face with projected sketch items is a not a recommended practice because it usually totally kills the curvature on the resulting edge. One might argue that one does not care about that curvature, but one will be puzzled in many cases why the the filleting in the next step fails 😉

There also is not really a need for the intermediate rings below the top surface that serve as additional loft profiles.

Despite the presence of a bug this can easily be accomplished with a number of techniques in Fusion 360, even with "just" solid modeling.

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oldtbone55 — Fri, 01 Feb 2019 19:34:57 GMT

@TrippyLighting wrote:

I've looked at the model and find that it exhibits quite an unorganized hack/slash technique. Components are being moved when not necessary. Sketches are not in the components that belong into and are not properly constrained and dimensioned etc.

Projecting sketches onto surfaces is for the most part is not a good technique. The surface can be directly split with split face and the unneeded faces can be deleted. In general these edges, instead of sketches should be used for lofting. Splitting a compound curved face with projected sketch items is a not a recommended practice because it usually totally kills the curvature on the resulting edge. One might argue that one does not care about that curvature, but one will be puzzled in many cases why the the filleting in the next step fails 😉

There also is not really a need for the intermediate rings below the top surface that serve as additional loft profiles.

Despite the presence of a bug this can easily be accomplished with a number of techniques in Fusion 360, even with "just" solid modeling.

Your response is appreciated Trippy. You definitely don't mince words or hold back on your opinion. I'm no expert by any means which is why I'm on the forum and can accept your criticism. Your points are valid and to be honest, some are beyond my understanding. I'm a hacker, yes, but it would be really helpful if you would not only criticize, but provide some guidance of how I could go about approaching this and use Fusion to get what I want. I don't have anywhere near the experience you do so folks like myself rely on people like you and Jeff Strater and others to help us. I guess what I'm saying is, I'll accept the negativity, but please provide some positive help if you're going to post back these kinds of replies.

Thanks.

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TrippyLighting — Fri, 01 Feb 2019 19:35:18 GMT

@oldtbone55 wrote:

please provide some positive help if you're going to post back these kinds of replies.

Will do so later. I did not have time to do a screencast from work 😉

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oldtbone55 — Fri, 01 Feb 2019 19:37:58 GMT

Thanks Peter. I do appreciate your honest replies. I'm trying to do better.

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TrippyLighting — Sat, 02 Feb 2019 00:57:40 GMT

So this first screencast is more a question than an answer. I need to understand what it actually is you are trying to achieve before making recommendations for better methods.

I do explain, however what I mean with sketches projected on compound surfaces creating problems.

When working with surfaces is is almost always better to work with edges than with projected sketch geometry.