Linking sketches so I can edit lofts (or other features)

[Anonymous]

Hi guys,

I am drawing a model plane fuselage. First, I drew the centerline in sketch 1. Then a vertical provile in sketch 2. Drew several cross sections based on the vertical profile. Made a new plane, projected the cross sections onto the plane, and drew the horizontal profile. I think I'm not getting the links and things right, because first when I try to loft I always get the error that the side rails are not intersecting all the profiles (cross sections), and after I got that working (by accident to be honest) I started putting gear inside the fuselage to sort out the spaces. I want to then make changes to the design to fit the gear better, and so my logic was I should go in and modify my vertical profile, since the cross sections were based on that, and the side profile was based on the cross sections, etc. But when I edit the vertical profile, I'm not getting any change to the other sketches and the resulting loft.

I must be making some fundamental mistake, and probably not linking the sketches correctly. Any help appreciated, thanks!!

Thomas

[Anonymous]

I played around a little bit with a new simpler drawing. I am getting the change in cross section when I change the vertical profile (drawn first). But the horizonal profile/rail that was draw from projections of the cross sections cannot update, so the loft cannot update with the edit.

Is that the 'correct' way to draw the side profiles/rails? If so, how can I get it linked correct? And if not, what is the right/better way to do it?

Thanks a million!

[Anonymous]

I rolled back on the original drawing I was working on and deleted some useless stuff, and tried to redraw some of the sketches. But, when I edit the vertical profile (increased height by 1mm at each profile) the cross sections are still not updating/linking to those points. I can't think of what I'm doing wrong/differently than the new simple test drawing I just did and posted in the last post.

[davebYYPCU · Accepted solution]

I have found Fusion very finicky for lofts with rails.

That said, your description of "projecting" may be your problem.  Certainly Fusion can and does what you are attempting.

it does not matter which comes first, rails or profiles, but you have to make sure the rails touch the profile.

The way to do it works for me is to make a separate sketch for every rail.

Use "intersect project" of the curves /lines that cross the relevant sketch plane, (will get a red dot)  and then you must snap your curve/lines to those red points, making them coincident.

when the loft is successful, editing the sketch that was "Intersect Projected" should update the 2nd sketch, and the loft will be okay.

I do not use snap to grid at anytime, as the grid may sometimes be close to those red projected points.

Hope this is helpful, but it may not be what the problem is, it is my interpretation of the questions and only some red points are visible between your rails and formers.

Browny

[TrippyLighting]

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@davebYYPCU wrote:

I have found Fusion very finicky for lofts with rails.

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That's an understatement 😉

@Anonymous It would be easier to answer if you'd share your design. Export as .f3d and atach to your next post please.

[Anonymous · Accepted solution]

Hi Thomas,

I have been working on a surfboard design recently and have the following solution which should work. I have attached a TEST file which should help explain my reasoning.

Apologies for the sometimes over explanation but this is an edited version of my surfboard method which I typed out as I was going along with the design.

1. Start with the plan shape. Use the Spline tool to design the half plan shape ensuring nodes at the points where you are going to have the cross sections.
2. Dimension this plan shape with vertical and horizontal dimensions to each of the nodes.
3. Go to Change Parameters and create parameters for each of the dimensions with meaningful, descriptive names e.g. width01, length01, etc.
4. If desired, the plan shape can now be mirrored to get a better idea of the board shape, but the half shape is adequate for the loft.
5. Next, create offset planes, on which the cross section shapes will be drawn. Be sure to give them meaningful matching names e.g. plane01, plane02, etc.
6. Create Sketch on the first plane and Project the relevant node of the Plan Shape into the sketch. Rename the sketch to xsection01. For now the Sketch will consist of one projected point only.
7. Do this for the all the planes, renaming each Sketch appropriately.
8. Next, design the cross section shapes on each of the above planes by editing each of the above single point sketches. Design the half cross section shape at this time.
9. In this way, because the projected points are automatically linked to the plan shape nodes, any changes made to the plan shape will automatically adjust the affected cross section accordingly. NOTE: This does not apply to length (longitudinal) dimension changes made to the plan shape. See below for solution.
10. In Change Parameters, change the offset plane dimensions to the relevant length parameter e.g. length01.
11. Now any length (longitudinal) changes made to the created parameters (in the Parameters window) will automatically adjust the plan shape and move the offset planes accordingly and the relevant cross section shape along with it.
12. Mirror the half cross section and convert the centre line to a construction line.
13. Now any width changes made to the created width parameters (in the Parameters window) will automatically be applied to the plan shape and the full cross section shapes.
14. Using Modify Loft select the full cross section shapes in order from tail to nose and the relevant rails.
15. That should do it!
16. Shape not quite right? Go into Change Parameters and change the applicable created parameters. The lofted shape will automatically update with these changes.

Hope this makes sense and is of assistance.

Regards

John

[Anonymous]

Guys, thanks for all the help! 🙂 I appreciate all the help through this forum and hope I will be proficient enough down the road to provide the same support to others.

Thomas