Designing to a curve

[Anonymous]

I've spent a while trying to find answers to my question, I suspect I don't know how to ask it properly.

I've made a rigid support for a flexible sheet with fixed-spaced notches in, but I'd like to do it less arbitrarily. What I want is to draw a line with the spacing for nubs that fit the notches, draw a curved shape  which represents the desired frame and then bend the line (or face/body) to the curve, while retaining the distance between and width of the nubs (so they align with the sheet after bending).

I'd be doing the bend from the center of the line, and I don't mind if there is a mismatch between the length of the curve / line.

Or put another way, I want to:

- create an elipse,
- place a point S mm along the elipse from point A on the elipse,
- place a second point S + Wmm along the elipse from A,
- place a third point (S + W) * 1 + S mm along the elipse from A,
- place a fourth point (S + W) * 2 mm along the elipse from A,

[g-andresen]

Hi,

please create a screencast and share your file.

günther

[etfrench]

Here's one way to put arbitrary points on an ellipse:

1. Sketch1: Draw an ellipse.
2. Create Plane along Path at distance: 0.
3. Create sketch on the plane.
4. Draw a circle at the origin of the sketch.
5. In the Surface workspace, Patch the circle.
6. Use Pattern On Path to create the Patches at the distance desired.  You may need to use more than one Pattern On Path if the spacing is not regular.
7. Create Sketch2 on the same plane as Sketch1.

1. Project the ellipse and each of the patches to Sketch2.  This will give you the intersections needed.

[Anonymous]

Hey, @g-andresen, I'll try but I really don't think it will be helpful since I've no idea how to even start.

What I'm doing is:

- create a line with anchor points that correspond to the fittings in a 3rd party flexible sheet,

- change translate that line into a shaped surface while retaining the distances along the surface between the anchor points continue to coincide with the fittings in the sheet when it is overlaid on the surface.

The one I made by hand:

If I change the shape, the distance between the anchors *must not change*, so ideally I want to create a baseline straight version of the frame that I can subsequently bend to a specific curve of given height/width.

[Anonymous]

Not sure why it ate the screenscast.

[etfrench]

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@Anonymous wrote:

If I change the shape, the distance between the anchors *must not change*, so ideally I want to create a baseline straight version of the frame that I can subsequently bend to a specific curve of given height/width.

---

The steps I outlined do precisely that. 

p.s. When you have symmetry in a model, it's best to use the mirror command instead of modeling both sides.

[Anonymous]

@etfrench I'm missing something because this turns out differently for me?

[etfrench]

First, I would turn of the grid and the snap to grid 😀  I don't think it has any benefit in parametric modeling.

You selected the wrong plane to project the circles.  When projected to a sketch on the same plane as the original ellipse, they will be lines.

[Anonymous]

@etfrench Which plane *should* I be using?

[Anonymous]

---

@etfrench wrote:

1. Sketch1: Draw an ellipse.
2. Create Plane along Path at distance: 0.
3. Create sketch on the plane.
4. Draw a circle at the origin of the sketch.
5. In the Surface workspace, Patch the circle.
6. Use Pattern On Path to create the Patches at the distance desired.  You may need to use more than one Pattern On Path if the spacing is not regular.
7. Create Sketch2 on the same plane as Sketch1.

---

Perhaps 3 and 7 are misleading and you simply meant

1. Sketch1: Draw an ellipse.
2. Create Plane along Path at distance: 0.
3. Sketch2 (coplanar with Sketch1): Draw a circle at origin.
4. Patch cirlce.
5. Use Pattern On Path to create the Patches at the distance desired.  You may need to use more than one Pattern On Path if the spacing is not regular.

[etfrench · Accepted solution]

No.  This is what I said:

1. Sketch1: Draw an ellipse.
2. Create Plane along Path at distance: 0.
3. Create sketch on the plane.
4. Draw a circle at the origin of the sketch.
5. In the Surface workspace, Patch the circle.
6. Use Pattern On Path to create the Patches at the distance desired. You may need to use more than one Pattern On Path if the spacing is not regular.
7. Create Sketch2 on the same plane as Sketch1.
8. Project the ellipse and each of the patches to Sketch2. This will give you the intersections needed.

The original post's numbering was defective for #8.  The image in the post shows what it should look like after #8.  In step #4 you can also use a rectangle with one corner at the origin.  This will give you an endpoint on the ellipse when projected instead of a midpoint with the circle.

You can also start the plane on path at .5.  In theory this should allow you to change the path and still have the points at the same distance apart and mirrored correctly.

[Anonymous]

Appreciate the clarification. I'll accept this as the answer, because it's *a* way to achieve it, what I was really hoping for was some way to draw the part as a straight line first and then bend it (again, I'm making a shape to hold a flexible sheet in various shapes

[etfrench]

The sheet metal tools may work better for you.  Either way, the distance between the points will actually be on a chord between the points, so depending on your tolerances you may need to specify each distance individually as a straight line instead of as a distance along the path.