|Raspberry PI E2712RSV1.0B1.1|
I downloaded Thing 28070 and printed it out
It would seem our Raspberry PI is unlike others, specifically: -
- The pitch of the audio and video connectors is different
- The PCB is 1 mm wider
- The network connector is longer
- There is a white plastic tab on the underside of the USB connectors which fouls
Essentially this means that the cases on Thingiverse would not work out of the box. The problem with Thingiverse is that most people post STL files which are surface models (not easily manipulated) and those that post source files often post SKP (Goolge Sketchup) or OpenScad, neither of which I use or are 'portable'. Of course designing a new case is entirely possible but in doing so the efforts of others are lost. To this end I decided to revisit the use of a CAD file converter.
CAD conversion tools should be avoided where ever possible as there are always translation errors. These errors result from things as simple as rounding up or down of dimensions, to complex issues such as how geometry should be interpreted and subsequently represented. I tread here where angels fear to walk!
The tool that popped out of a Goolge search for conversion of STL files to STEP files was InStep V2.0 by Solveering. I prefer STEP files as once they import into my CAD software they are quite manageable (modifiable), probably resulting from the fact that its format is defined in an ISO standard. Suitably downloaded and installed I threw the file at InStep and checked out the error report in InStep. It was quite an extensive list of errors and InStep's STL mesh correction tools were unable to fix the issue so it might be a dead end.
Issues with STL files are not particularly surprising as exported STL files often have errors and junk in them. The easiest tool to fix most STL files errors is NetFab which just about any one can use. Certainly it has fixed any STL's I have downloaded from Thingiverse or created for printing with Pronterface. In this instance though it was too tough a nut to crack. I had one more thing to try before starting from scratch.
|MeshLab with Thing 28070|
A more sophisticated tool I found some time ago is MeshLab. This has quite a number of menu options and I watched some videos on YouTube to see what it could do. Meshlab has lots of clean up options and the ability to create a script which can be used on imported STL files. Here is a copy of the script (.mlx file) I used to clean up Thing 28070:
filter name="Remove Duplicate Faces"
filter name="Remove Duplicated Vertex"
filter name="Merge Close Vertices" param max="1.09781" min="0" name="Threshold" type="RichAbsPerc" value="0.15489"
*** InStep V2.0 Data Summary ***
File Name: RaspberryPi_v15 ML.stl
File Path: C:\28070 - Pi Case
Report Location: C:\Temp\tmp148.txt
Independent Bodies : 2
Total number of Vertices : 2658
Total number of Edges : 8142
### Features/Facets for the Bodies ###
Body 1 : 4202
Body 2 : 1226
### Degenerate Features ###
### Edge Issues ###
No Issues detected
### Vertex Proximity ###
Point 0 to Point 1 Distance is smallest at 0.024337
Using the Export option from from InStep I created a STEP file, then imported the STEP file it into my CAD software and to my surprise it worked!
|InStep V2.0 with Thing 28070|
In working with the files in my CAD system there have been some minor issues. It seems that the STEP file has to have operations performed on it separately from natively generated geometry. So a cut may have to be performed in two operations. However for the most part it proved very robust.
|Imported Thing 28070 STEP file generated by InStep|
I can't promise the next STL will 'fix' so readily but if Solveering keep this tool available, it could be a very useful facility to have available.
2016 Edit :
- Solveering upgraded the software.
- Do check out my later post on FreeCad
Inspired by Thing 24721 and Thing 28070 is Thing 30646
|Thing 30646 with Raspberry PI (RS Version B1.1)|
|Rendering of PCB STEP file Thing 21718|
|Thing 30646 RS Raspberry PI case|