D.I.Y. Reverse Engineering. Part Three
07Dec10 by Matt Sinclair
The third post in this series looks at what is an inevitable feature of any product development process – the checking, correction and modification that occurs when the first prototypes are available. Even though I had reverse engineered an existing (i.e. previously ‘proven’) product this was still a stage I was expecting to have to go through; the inaccuracies in measuring together with the new tolerances introduced by the selective laser sintering (SLS) process meant it was highly unlikely that everything would fit first time. Even so, it was still a surprise to see how much my model differed from the original product.
Having created the Solidworks CAD model as described in the previous post, an .stl file was exported for each part so that SLS prototypes could be made. In common with most CAD software Solidworks allows you to tune the accuracy of the .stl file by adjusting the linear and angular tolerances. Playing around with these options resulted in some large variations in file size:
| Linear Tolerance (mm) | Angular Tolerance (degrees) | Number of Triangles | File Size (Mb)
|
| 0.025 | 5.0 | 1,206,957 | 9,711 |
| 0.015 | 5.0 | 1,908,258 | 17,398 |
| 0.025 | 2.5 | 4,027,601 | 32,690 |
| 0.015 | 1.0 | 21,407,422 | 167,857 |
POSTED IN: 04 New Design Processes, 05 Enabling End User Design, No Comments