# Loft through purple dots

**URL:** <https://discourse.shapr3d.com/t/loft-through-purple-dots/33494>\
**Category:** Modeling Questions\
**Created:** [August 30, 2024, 7:12am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494 "2024-08-30T07:12:42Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 7:12am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/1 "2024-08-30T07:12:42Z")

</div>

I’m struggling for a while in order to make wing profiles. I had some support on this forum but still cannot pickup the logic of designing with loft and guides (at one point I’m wondering if I should stick with this software in order to design exactly what I want…)  
Here’s the friction point:  
-I design a first sketch profile for my wing. I can see the purple dots on it that should allow me to connect guides  
-I move and copy this first sketch to further build my wing. I scale this copied and moved sketch to design my future wing and I figure out that on this sketch there is no purple dots ! So I won’t be able to use guides… (screen captures attached)  
What am I doing wrong? Or is it a bug in Shapr 3D?  
Where can I find a comprehensive demo or tutorial to design foils? I’m designing hydrofoil wings and I’m totally stuck with this issue.

 ![IMG_0483](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/0/d/0ddd0ba72e5aa97e1eae188c9baed40b14328455.jpeg)

---

<div class="post-metadata">

**Author:** ![jean-philippe2](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jean-philippe2/32/27353_2.png) [@jean-philippe2](https://discourse.shapr3d.com/u/jean-philippe2)\
**Post date:** [August 30, 2024, 7:31am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/2 "2024-08-30T07:31:06Z")

</div>

H  
Here infos about Loft.

[Loft](https://support.shapr3d.com/hc/en-us/articles/7874427572508-Loft#history-settings)

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 8:06am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/3 "2024-08-30T08:06:48Z")

</div>

Hello Jean-Philippe  
Thanks for the RTFM but no answer in the manual about my issue.

---

<div class="post-metadata">

**Author:** ![jean-philippe2](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jean-philippe2/32/27353_2.png) [@jean-philippe2](https://discourse.shapr3d.com/u/jean-philippe2)\
**Post date:** [August 30, 2024, 8:28am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/4 "2024-08-30T08:28:52Z")

</div>

Can you share your file and explain what you want in several words

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 9:17am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/5 "2024-08-30T09:17:23Z")

</div>

I don’t think sharing the file helps as screen capture above is explicit. My goal is to get the purple dots on profile sketches when I want to connect lines in order to use theses lines as guides when I will loft later.

---

<div class="post-metadata">

**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [August 30, 2024, 9:59am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/6 "2024-08-30T09:59:15Z")

</div>

May be i can help, a little bit later(tonight) I’m no with my ipad.  
I could made wing bodyes with the guided loft. My wings , tapered, and warped…

 ![IMG_4663](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/c/6/c61521d7453c50772670bb95adb394e54c6bb2e5.jpeg)

---

<div class="post-metadata">

**Author:** ![jean-philippe2](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jean-philippe2/32/27353_2.png) [@jean-philippe2](https://discourse.shapr3d.com/u/jean-philippe2)\
**Post date:** [August 30, 2024, 10:07am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/7 "2024-08-30T10:07:43Z")

</div>

like that ?  
See screenshot

 ![screen](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/3/9/39c3310e5ce73071c7ee9890b6f30cfaa9d2c5a3.jpeg)

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 11:36am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/8 "2024-08-30T11:36:27Z")

</div>

Yes exactly, on my platform iPad or Macbook M1 I cannot get the purple dots on the section sketches to connect the lines.  
IE on your screen shot : if I start from your upper left section and go with my line to the upper center section, the upper center section does not display the necessary purple dots to validate the line connection.  
I would like to have a reliable way to get the dots displayed

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 11:37am UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/9 "2024-08-30T11:37:38Z")

</div>

Oh yes you’re welcome. I picked up the concept and practise but cannot get the necessary purple dots for connection

---

<div class="post-metadata">

**Author:** ![jean-philippe2](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jean-philippe2/32/27353_2.png) [@jean-philippe2](https://discourse.shapr3d.com/u/jean-philippe2)\
**Post date:** [August 30, 2024, 1:15pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/10 "2024-08-30T13:15:50Z")

</div>

Here a video.  
With and without guide

---

<div class="post-metadata">

**Author:** ![Oregonerd](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/oregonerd/32/8012_2.png) [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)\
**Post date:** [August 30, 2024, 2:53pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/11 "2024-08-30T14:53:37Z")

</div>

I don’t see a closed sketch to loft. Only closed sketches can be lofted or extruded. A closed sketch would be blue.

---

<div class="post-metadata">

**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [August 30, 2024, 3:02pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/12 "2024-08-30T15:02:56Z")

</div>

Here is my wing tip, tapered and warped, -1 deg at the end ( reduce the drag) , the airfoils are different.

 ![IMG_1682](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/7/8/785b5ccd9c3649ba5362b68f47d5505f8696fd46.jpeg)

At first set my airfoils on same horizonal costruction line.

- the end profil was moved towards
- set a vertical tangent line to both of airfoils leading edge
- Turned the end profil 1 deg, around the tangent point of the leading edge. Then correction the trailing edge to vertical
- Set a new vertical tangentpoint for the end foil( because the leading edge not circle rounded)
- Set a horizontal short construction line
- made construction planes with the”3point plane” , used the vertical tangent lines on the leading edge
- At this moment the purple dot are visible on the plane and can be draw the guide line
- Same at the trailing edge, used the the vertical edge to draw the “3point plane”  
In that case the guide lines fit to the airfols and the loft is worked.

If you have symmetrical foils the process more simple

 ![IMG_1684](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/6/e/6e32813f71ef849328340a5de83db5d7bd40fe8f.jpeg)  
 ![IMG_1683](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/1/8/18105f67b4f9e68d9f59f916be1020d563ac2aab.jpeg)

https://www.loom.com/embed/946877d4d52149fbac6fbfc2bd495757

---

<div class="post-metadata">

**Author:** ![Bob3DPO](https://avatars.discourse-cdn.com/v4/letter/b/7993a0/32.png) [@Bob3DPO](https://discourse.shapr3d.com/u/Bob3DPO)\
**Post date:** [August 30, 2024, 3:07pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/13 "2024-08-30T15:07:36Z")

</div>

Hi Michel,

> [@ecreatures](#):
>
> I would like to have a reliable way to get the dots displayed

The intersection of a plane and a sketch will give you the purple dots. They are the intersection points. Now when you sketch on the plane, the purple dots are ready to use. When using spline for the guide rails, make sure to select “fit spline” (not control) and select the purple dot as point.

---

<div class="post-metadata">

**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [August 30, 2024, 3:08pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/14 "2024-08-30T15:08:27Z")

</div>

Here is my vertical fin with rudder:  
Was drawn with a previus version of S3D  
The logic is same three foils with guide line.  
It is for mould.

[![](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/2/9/29f93e46fb63a4c191a3e3cdbd56430aefefa507.jpeg "Fin with loft 2 in Shapr3D") ](https://www.youtube.com/watch?v=295MapU279k)

---

<div class="post-metadata">

**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [August 30, 2024, 3:17pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/15 "2024-08-30T15:17:09Z")

</div>

Hi Bob!

> [@Bob3DPO](#):
>
> for the guide rails, make sure to select “fit spline”

I think work with control points splines too..

 ![IMG_1685](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/b/9/b935af5725865d40ab1b3e928a930e22b23f1bdf.jpeg)

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 3:24pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/16 "2024-08-30T15:24:27Z")

</div>

Merci Jean Philippe. But my issue is prior to the loft action. My issue is connecting the 2 sections with lines. To do so I need to get purple dots on the section to connect the line.

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 3:26pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/17 "2024-08-30T15:26:03Z")

</div>

It is closed as it is the first sketch that I copied and scale. thanks for the tip

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 3:35pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/18 "2024-08-30T15:35:36Z")

</div>

Thanks Bob, I guess you nailed it, the sketch needs to be on a plane to display the dots. In my case, I did not create a plane for the second sketch where I was looking for the dots.

---

<div class="post-metadata">

**Author:** ![JST](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@JST](https://discourse.shapr3d.com/u/JST)\
**Post date:** [August 30, 2024, 3:41pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/19 "2024-08-30T15:41:37Z")

</div>

And one more note .

The guide line should be start from the cross-section to the end cross-section, exactly.

---

<div class="post-metadata">

**Author:** ![ecreatures](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/ecreatures/32/15450_2.png) [@ecreatures](https://discourse.shapr3d.com/u/ecreatures)\
**Post date:** [August 30, 2024, 3:55pm UTC](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494/20 "2024-08-30T15:55:15Z")

</div>

I tried and failed, even with sketch on a parralel. plane the second sketch does not display the purple dots. I’m lost

 ![IMG_0485](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/9/e/9e4a08e71a49a1482d275fa439e540c82bbe9715.jpeg)

[Next page](https://discourse.shapr3d.com/t/loft-through-purple-dots/33494.md?page=2)