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removing sharp transitions from loft that automatically created when using rails

mohiedd
Explorer

removing sharp transitions from loft that automatically created when using rails

mohiedd
Explorer
Explorer

Hello. I've created a loft that uses a few guide rails, but when the loft is completed there are some sharp lines dividing the loft surface in various places (not placed by me, automatic) and those become the boundary of some rough transitions on the surface. I would like to remove these. the loft rails dont have to be exact, i just want the general shape but without the dents that occur in these areas. Thank you.

mohiedd_0-1716503975809.pngmohiedd_1-1716503987912.png

note, the line over here        ^   does not match the exact location of the rail in the above picture

mohiedd_3-1716504101247.png

 

 

 

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davebYYPCU
Consultant
Consultant

Try adjusting the Rail shape and positions - not so tight in those areas.

Or more profiles.

 

Might helpโ€ฆ.

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mohiedd
Explorer
Explorer

I've tried adding more rails, but this seems to be a slippery slope. I'm wondering if there is a way to use the rails as only a rough constraint and not exact, this way perhaps fusion would be able to smooth out the transitions itself. either that or if there was a way to simply correct concave surfaces, such as using "create form" or something similar.

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jeff_strater
Community Manager
Community Manager
Accepted solution

"I've tried adding more rails, but this seems to be a slippery slope. I'm wondering if there is a way to use the rails as only a rough constraint and not exact, this way perhaps fusion would be able to smooth out the transitions itself."

 

This is what Centerline Rails do.  However, you are limited to only a single centerline rail per loft.  Not sure if you can achieve the results you are after with one centerline, but it might be worth trying.

 

either that or if there was a way to simply correct concave surfaces, such as using "create form" or something similar."

 

You can try this as a T-Spline loft in the Form workspace, and modify the output manually.  I have low expectations there, to be honest.  T-Splines loft does not have the level of control as solid/surface loft.  You can try to manually create faces in T-Splines and use Replace Face, but that is likely to be very challenging, as well.

 

I'm pretty confident that you should be able to get a decent surface out of Loft.  Ironically, sometimes fewer rails produce a better surface.  Also, check the curvature combs for your profiles.  Bad curvature on profile curves can sometimes cause undesirable surfaces to be produced.


Jeff Strater
Engineering Director
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davebYYPCU
Consultant
Consultant

You need more control,  I would create a centre profile, connected to the rails, (lot of eyeballing)

Just as create form might / would work if you have the experience with them.

 

Might helpโ€ฆ.

 

 

 

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mohiedd
Explorer
Explorer
thanks, ill keep that in mind.
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davebYYPCU
Consultant
Consultant
Accepted solution

Some of your rails appear to be at random locations and too many spline points would not be helping.

 

Rails at the midpoint areas, does help....

 

tpswb.PNG

 

Bottom handles vertical, top handles horizontal, adjust for shape.

 

tpswb2.PNG

 

Might help.....

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mohiedd
Explorer
Explorer
thanks, good point about the number of spline points
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TrippyLighting
Consultant
Consultant

@davebYYPCU's statement that you need more control is correct. However, the loft he shows still shows undesirable artifacts. If you can share your model, I can possibly demonstrate how to remove those.


EESignature

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mohiedd
Explorer
Explorer

Thanks. if you look around the model, you can see at least 5 instances of these concave points.

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TrippyLighting
Consultant
Consultant

This is the first sketch in your model and it already has two if not three big no-no's i it.

1. You use way too many spline points to trace the shape. The curvature comb analysis tool shows very wavy curvature. That will NEVER create a smooth loft.

You are likely better off using multiple curves and some patience ๐Ÿ˜‰

 

2. Never mirror an entire sketch, particularly not a fit point spline. Model half of the sketch and geometry and then geometry.

 

Your attempt:

 

TrippyLighting_0-1716575089054.png

 

 

My approach:

TrippyLighting_1-1716575127109.png

 

Before starting to model, you should measure a dimension of the object and then calibrate the canvas in Fusion to that dimension.  then you can sketch based on that canvas, without having to scale anything.

 


EESignature

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mohiedd
Explorer
Explorer

thanks, ill redraw the trace. but this part, what exactly do you mean by this: "Model half of the sketch and geometry and then geometry" instead of mirroring? im somewhat inexperienced with fusion :0

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