# Issues tracing an .stl

**URL:** <https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287>\
**Category:** Modeling Questions\
**Created:** [October 6, 2023, 3:25pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287 "2023-10-06T15:25:11Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![jcclow](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jcclow/32/23888_2.png) [@jcclow](https://discourse.shapr3d.com/u/jcclow)\
**Post date:** [October 6, 2023, 3:25pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/1 "2023-10-06T15:25:11Z")

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I am trying to trace an .stl file of a 3D printer hot end to make an adapter for it. I’ve gotten most of it completed, but the heat block has some interesting geometry that I’m having an issue with. I know how to create the geometry, but when I try to trace the geometry with a spline, I am getting some odd behavior, and am wondering if this is a bug or I’m doing something wrong.

There are two issues that I’m experiencing…

1. I’m not sure why the points and lines on the imported object are highlighted when I place a construction plane on a face of it. They are distracting and not helpful, because you can not edit the points, lines or faces of the imported .stl.
2. When I try to trace the lines of the imported object with the fit spline tool, as soon as I draw the first segment and lift the pencil, a full control point spline is placed on top of the line of the imported object. When I try to place the next segment of the spline, a new control point spline is placed on the previous one, but with a different alignment. This would be great if the spline it placed was aligned perfectly with the imported geometry, but it isn’t. Here’s a video of it…

I have also included the file I am working on for others to try and see if they are experiencing the same issue.

[Mount v1 Copy.shapr](https://discourse.shapr3d.com/uploads/short-url/o0kIL8ZdNnRI6fV7V5kWF9tzjH1.shapr) (35.3 KB)

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**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [October 6, 2023, 3:55pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/2 "2023-10-06T15:55:28Z")

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I checked out your file. First, the imported model is not an STL file. It is a solid body that cannot be edited within Shapr3D. If you want to trace as you intended, move the plane a short known distance from the surface then draw you spline.

As a test, I exported your file as an STL then imported the STL and placed it next to your imported body. The STL is a mesh file and selecting any one surface selects the entire mesh. Here it is.

[HotBlock.shapr](https://discourse.shapr3d.com/uploads/short-url/ob0YFKj9aGKuhgJQxTgDggif1KY.shapr) (154.5 KB)

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**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [October 6, 2023, 3:58pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/3 "2023-10-06T15:58:48Z")

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Actually, no need to trace. Move the plane away and use the **Project** tool.

[https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/1/b/1b642d61fdde7624d82d0b33d3ed645a7e4760af.mov](https://us1.discourse-cdn.com/flex002/uploads/shapr3d/original/3X/1/b/1b642d61fdde7624d82d0b33d3ed645a7e4760af.mov)

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**Author:** ![jcclow](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jcclow/32/23888_2.png) [@jcclow](https://discourse.shapr3d.com/u/jcclow)\
**Post date:** [October 6, 2023, 5:10pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/4 "2023-10-06T17:10:41Z")

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Sorry, it’s a .step file.

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<div class="post-metadata">

**Author:** ![jcclow](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jcclow/32/23888_2.png) [@jcclow](https://discourse.shapr3d.com/u/jcclow)\
**Post date:** [October 6, 2023, 5:11pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/5 "2023-10-06T17:11:49Z")

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TigerMike…you are a monster! Thanks for this.

It’s still interesting that when trying to create the original spline, multiple ones are created. I’m still curious what causes that.

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<div class="post-metadata">

**Author:** ![TigerMike](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/tigermike/32/32650_2.png) [@TigerMike](https://discourse.shapr3d.com/u/TigerMike)\
**Post date:** [October 6, 2023, 5:46pm UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/6 "2023-10-06T17:46:53Z")

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🐅 Grrrrrrrrr

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**Author:** ![KPeter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/kpeter/32/7644_2.png) [@KPeter](https://discourse.shapr3d.com/u/KPeter)\
**Post date:** [October 9, 2023, 11:15am UTC](https://discourse.shapr3d.com/t/issues-tracing-an-stl/28287/7 "2023-10-09T11:15:57Z")

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Hey @jcclow,  
The spline you see appearing is the projection of the edge. As the control point you place has to be snapped to a sketch object, the edge is automatically projected.