Spline not staying in 2D plane

[thuffam]

I have a sketch with a simple rectangle and a spline replacing one end (so a rounded end to the rectangle).

When I try to extrude it, Fusion would not allow me to select the plane. After 2 days of googling all I can assume is that some of it is off plane and now 3D. 

When I delete and recreate the spline, when I adjust the end point things to adjust the curve, when I finish the sketch, it draws completely differently...and when I revolve the drawing I can see that it has gone somewhere in 3D.

I have the option "3D Sketch" turned off (unchecked) and the preference "Design - Allow 3D sketching of lines and splines" also turned off.

Is this a bug with Fusion?  It means I cannot use it to create a simple spline and extrude it.  

My sketch does have some elements from another sketch projected onto it.

I have tried recreating a sketch with the similar items - a projection and spline - but it seems to work.   So why is it not working for my other sketch?  It seems to be ignoring the options and preferences.  I have tried closing and reopening the sketch and Fusion.

[jeff_strater]

Please do not double post.  See:  how-to-constrain-a-sketch-fit-point-spline-to-a-2d-plane-so-it 

[g-andresen]

Hi,

Please follow up on your request in this post, as the "duplicate post" -  @jeff_strater  -   mentioned, referred to mesh bodies.
However, since you have said that you are not referring to such, please provide a file for inspection.

günther

[thuffam]

@jeff_strater I am sorry for what might seem like a double post - but on re-reading the prior post, I had asked a question on someone else's post - but I had subsequently realised they were doing something quite different to me - they were trying to trace a mesh -where I am not using a mesh, nor tracing at all.    Seeing as there is no ability to remove posts I have just deleted the text of my other question - apologies for any inconvenience caused.

Back to the issue at hand.... I simply have some sketches and extrusions.  So at a loss as to why the spline in a sketch keeps wandering off into 3D.   

I simply have a 

[thuffam]

Correct - not using meshes - that was wrong of me to add my question to that post - I have done my best to remove it. Apologies for any inconvenience caused.

Please find file attached.  The offending sketch is called "Sketch9_2PartFrontLarge"   it was used for the subsequent extrusion in the time line.

Much appreciated and thank you very much in advance for any assistance.

[jeff_strater]

Thanks for sharing the design.  Because sketch has no "history" there is no way to tell how your sketch got in that state, but I do have a theory - there are purple "included/projected" sketch points that are not on the plane.  If you ever had 3D sketch enabled, you probably snapped to those points.  The video below explains how I found and fixed those.

[thuffam]

Hi Jeff. Thank you so much for taking the time to look at this.

Yes I suspect I turned the 3D settings off after creating the sketch.

I have tried your solution and while it moves the sketch onto a plane... it is not where it needs to be - which is where it was originally. And it has messed up the rest of my model (this sketch was about 1/2 way along the time line).

What is interesting.. is move-to-sketch-plane.... showed me that my sketch wasnt on the plane I thought it was - I thought I had created an offset plane from the centre... and that that was the sketch plane... obviously not.

I think I need to do some more Fusion tutorials.. I've already invested many weeks into this model and several days with this particular issue.... so will stop digging. 

The fact I could so easily paint myself into a corner is a concern... suspect my approach is fundamentally flawed.  

Will start again.

Thanks again for your help, much appreciated.