Loft problem

[0502880]

Hello,

I have a problem to loft a cap between two surfaces; http://a360.co/1NS4JdU . I have tried to make loft with three (tangent) profiles by using two surface boundaries as guide curves and didn't manage to do it. Loft problem or problems with my model?

-Juha

[michallach81]

Trim both surfaces, so you would left with only half, then loft  and mirror to get full shape:

[0502880]

Thank's for your "trick"! But I expect, that this loft should work without splitting and mirroring... A software bug?

[michallach81]

No it's not a bug, rather limitation. Loft need enough data to avoid creating self-intersecting body. I've checked your file once again an it should work without trimming. Take a look:

Michał

[0502880]

Ok, but it's still a little bit confusing, that Fusion gives several warnings when implementing that loft; The loft would intersect itself, Rail(s) cannot be tangent to profiles... Any comment from Fusion development team?

[michallach81]

Tangency in Loft tool applies to surfaces. If you would loft from curve to curve there will be no Tangency option at all.

[Simon.Hern]

Hi @0502880

I'm a bit confused by this.  It looks like the loft (two profiles with tangent surface constraints, three rail curves) that's in the model you shared, and also in @michallach81's gif, is correct.  Is that right?

But I'm running into a lot of errors ("Rail(s) cannot be tangent to profiles!" in particular) when I try to rebuild it.  Is that the problem you're raising?

Thanks,

Simon

[0502880]

Hi Simon,

that's just the loft I was asking. Fusion was somehow able to do the loft between those two surfaces (with three rail curves), but it gave several warnings (Rail(s) cannot be tangent to profiles). Should loft accept smooth continuity between those two surfaces?

-Juha

[michallach81]

In my opinion warning about tangent rail, is just a bug in warning system, not in modeling. Fusion couldn't create that loft with certain inputs, but also couldn't find right warning that would describe that situation.

Why we saw those warnings at all? Because Fusion don't wait until we pick all entities and options, Fusion try to create feature while we defining our design.

Michał

[Simon.Hern]

Hi Juha.

It looks like part of the problem in this case is that the loft (with tangency and all three rails) builds correctly if the profiles are selected in one order, but fails if the profiles are selected in the reverse order.  Obviously that shouldn't happen.  I'll log this as a bug and see if we can do something about it.

More generally, I think it's actually okay for loft to sometimes display warnings/errors as profiles, rails, and tangency conditions are being added.  Each addition to the loft can significantly change the surface shape, and in a case like this the loft can often end up reporting an error because the surface it's currently building self-intersects.  It's only when all three rails have been specified in this case that the loft has enough information to build a surface with a good shape.

That said, the error messages can be very confusing at times (in particular, the message "Rail(s) cannot be tangent to profiles!" is misleading; the problem is not with the rails but with the shape the loft is trying to build).

Simon

P.S. I typed too slow!  Michal's reply already says what I was trying to.

[michallach81]

Another tip, if you've created surface through t-splines then try to avoid making transition with surfacing tools. If you decided to use t-splines then you should create all shape in TS.
Why, read this page, at least my post with a lot of animated gifs.

Michał

[0502880]

Thank's for the conversation. I understand well all mentioned aspects and restrictions and I suppose, that all CAD systems have their "weird" behaviours. But still it could be best if you shouldn't get any unnessecary warnings and the commands should work predictable way. But the world seems not to be ready jet ;))

Yes, I understand well, that it should be best to do whole shape in ts, but I have found it quite difficult to make very precise small details with controlled "fillets" in sculpt environment. But probably it's also my incompetence to do them.

[Anonymous]

Hi, I've been having some trouble with modeling this bench back with the loft tool: http://a360.co/2rtzamt

I'm not sure if is because they are perpendicular. Can anyone show me how to do it?

Thanks a lot!

[0502880]

Hi @Anonymous,

couldn't download/open your file in Fusion. Have you shared a public link to your file in the Data Panel? Could you try to do it again?

-Juha

[davebYYPCU]

Loft is not the right tool for this one,

.I could only get the model finished with Extrude for the plate, then Extrude > intersect with the profile,

Fusion did not want to work correct with the profile first then the plate,

All the profiles in the same sketch is not a normal proceedure,

I am not used to DM, so you can't read my time line, you can Ëdit the Extrudes to see how it was done by reading the settings in the Dialogue Boxes.

Save my file to your hard drive, then

Use "New Design from file" in the File menu....

Might help....

[Anonymous]

##- thanks @davebYYPCU you have done it almost right, though I didn't
understand how you finally extruded so that the upper part is shorter than the
bottom. 1) you extruded the lateral view, 2) you intersected with the front
view? how do you that? -##

Sent with Mixmax

[davebYYPCU]

You mean how did I make the second extrude?

It is the same

Model > Extrude  - Plate Profile, - Symmetric, - Intersect. Not cut, not join, etc.

If things didn't line up that's because your sketch has the problem not the Modelling features,

I don't change your file data unless it is asked for, helps me show you the way forward.

So in Timeline mode I would have had two sketches.  Edit sketch would fix that,

but with DM - I guess you have to delete and redraw. Direct Modellers might even disagree with my observation, but I am not sure of anything in DM.

[Anonymous]

@davebYYPCU thanks I solved it! I don't know why once the sketch is imported, why can it save in Timeline Mode?

[davebYYPCU]

I think it is your settings or Preference, Timeline is off.

With Timeline On, you can import Sketch and will go into a base feature, in that base feature you can Edit sketch, then close Base Feature, 

with Timeline Off, no Edit Sketch available, that I could find.

[Anonymous]

Hey Guys i am having the same problem too! 

I tried splitting the two surface so its half.

Tried to do a loft between the surfaces but it gave me an error saying its intersecting itself

If anyone can help that would be great!

Hoki