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10 Mar 2015, 4:32

DesignSpark Mechanical - Reverse Engineering

This blog takes you through an interesting journey of reverse engineering a real-life object into its 3D digital counterpart.

DesignSpark Mechanical was born with the objective of helping people transform their ideas rapidly into real working prototypes. One of the stand-outs in a flurry of features is reverse engineering; the ability to recreate a perfect model from digital scans.

In this blog, we use a mug and bowl as simple examples to demonstrate the reverse engineering process.

Let's breakdown this 'process':
1. Use a hand-held 3D scanner to get a detailed scan of the object.
2. Import into DesignSpark Mechanical in compatible format (*.STL, *.OBJ, etc.), perform repairs on imperfections in the scanned mesh and re-create solid model with software features .
3. Export reverse engineered model as '*.STL' for 3D printing.

Step 1: 3D Scanning

The 3D systems hand-held "Sense 3D Scanner" is used in this step. For more information and purchasing, check RS online (stock no.: 799-0480)

3D Systems Sense 3D Scanner

 

 

 

 

 

 

 

The object to be scanned is placed on the table top with enough space to go around with the scanner. To keep the object in focus, a constant separation must be maintained between the scanner and object.
To aid with this, a makeshift guide using colored adhesive tape is placed on the floor.

Here are the setup images and scanning seen in two fun time-lapse videos.

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Objects to be scanned and track guide (yellow tape) for scanning

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Scanner mounted on laptop

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Using the 'Sense' 3D scanning utility, the scans are exported as 'OBJ' files for further editing in DesignSpark Mechanical.

Step 2: Re-creating the models in DSM

The scanned model is contained as a mesh in the OBJ file which we will use as a reference to re-create the solid 3D models.

Commonly used DesignSpark Mechanical features/tools for below design steps.

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2.1. The Cup
We re-create the cup through the following steps:
a) The 'OBJ' file is imported into DSM.

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b) The 'Select' tool is dropped down and 'Using Paint' is chosen.

c) A portion on the outer surface of the cup mesh is paint selected and a 'cylinder' is placed from the 'Insert' tab.

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d) Using the measure tool, the thickness of the cup's wall is measured. The value is used to hollow the cylinder using shell tool by selecting the top face.

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The cup now starts taking shape.

e) Next, to smooth the cup's rim the scanned mesh is used as the reference. A plane is placed at the centre of the mesh and design is switched to section view.

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Using the spline tool, the curve of the rim is sketched. With the revolve option of the Pull tool (with 'no merge' setting), the rounded shape of the rim is obtained.

f) To merge the shape with the cup, the combine tool is used with the cylinder as target and the new shape as cutter. After completing the operation, the cut portions are deleted.

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g) To re-create the handle, we switch back to section view seen in step (e). Again using the spline tool, the exact shape is obtained.

In 3D mode, the thickness of the handle is set using the pull tool with the scanned mesh as reference.

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2.2. The Bowl

Similar to the cup, the scanned mesh is used as the reference to insert and modify solids.

a) The 'OBJ' for the bowl is imported into DSM.

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b) Using the paint select tool, the outer surface of the bowl mesh is highlighted and a sphere inserted.

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c) With the split body tool and appropriately placed plane as cutter, the hemispherical shape of the bowl is achieved.

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d) By placing a plane at the centre of the mesh and bowl solid and switching to section view, the shape of the depression at the bottom of the bowl is sketched with the spline tool.

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e) The sketched spline is revolved with the pull tool and the depression is carved out with the combine tool.

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f) The rough edges are rounded with the pull tool. The solid bowl is complete.

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Step 3: 3D Printing

To examine how well we have reverse engineered the actual object, a 3D print will be necessary.

Both objects are output as STL files and printed with the 'RS IdeaWerk FDM 3D Printer' (RS stock no.: 828-6356)
RS IdeaWerk FDM 3D Printer

 

 

 

 

 

 

 

 

 

Here are the results:

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Comparison of original vs. reverse engineered:

Original Rev. Engineered with DSM
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Don't they look like clones ? :)) That's the power of reverse engineering with DSM. Let us know your thoughts and if this has inspired you to start any project of your own ?

 

A curious mind with a passion for 3D CAD & rapid prototyping. Working towards improving the DesignSpark Mechanical software at RS, add-in for SolidWorks 3D among other projects.

10 Mar 2015, 4:32