Rail is not smooth

[3D_Ken]

I was well into a project when I found that I needed to make (what seemed to be) a minor correction to the original sketch.  After the modification, I am getting "Rail is not smooth" errors on Loft-5.  I have tried various things, but have gotten nowhere.  Any assistance would be greatly appreciated.  (file attached)

[wersy]

How about if you use mirror.

[3D_Ken]

I'm sorry, I tried working with your solution and it doesn't seem to solve my problem.  If I use your steps and leave Loft5 in place, Loft5 still shows an error.  If I disable Loft5, most all of the following steps disable themselves.

What am I missing?

[laughingcreek]

because the sketch isn't constrained properly, it's pretty easy to bump things out of place.  here you can see the arc that makes up part of the rail in question isn't constrained, so it's no longer tangent to the line.  I added a constraint so it would be and the error in the loft goes away.

@wersy - is right though.  this thing is symmetrical, so just sketching half of it and mirroring will make sketch's easier to deal with.

[davebYYPCU · Accepted solution]

That's because the meaning of that error is that rails must be tangent connected, and close enough is not good enough.

Add Tangent constraint here.

Fully constrained sketches are more stable.

Mirror half - requires the centre line dummy body edge to maintain the curvature at the mirror line, I would not mirror this one.

Might help.....

[TrippyLighting]

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@davebYYPCU wrote:

Mirror half - requires the centre line dummy body edge to maintain the curvature at the mirror line, I would not mirror this one.

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I assume what you mean is that you need a helper surface (tangency ribbon), but if we do that, Fusion will complain about the rail missing the profile.

The reason for that is also that the sketch isn't properly constrained.

I personally would also only loft half despite it being more work initially. Through many projects I've learned that in the end I often need that additional helper surface, or that additional center splint in the top surface, for other modeling tasks down the line.

[3D_Ken]

The tangent solved the problem. (That was easy) Thanks much. I had tried fixing with Coincident, which did not help. I guess, in this case, I don't understand the difference.

[davebYYPCU]

Coincident end points is also required.

Tangent is the not smooth part.  Loft error showed where the problem is with a red blob.

As Alex said, without it, he exaggerated the problem when he dragged the curve and there was a sharp corner there until he fixed the centre point.

This and Trippys info, show why -fully defined is recommended.  (All black articles)

Might help….