I'm developing a 19" rack mount "case" in OpenSCAD for the Raspberry Pi
2 Model B. I would like to have the mechanical dimensions to put the holes and cutouts at the right places. The only thing I found are measurements from the top but not from the side or front/back.
Two 2.5mm (drilled 2.9mm for M2.5 screw) non plated mounting holes have been provided to assist with ATE test mounting. Positions of these holes relative to the bottom left of the PCB (Power Input Corner) are:
Corner: 0.0mm,0.0mm First Mount: 25.5mm,18.0mm Second Mount: 80.1mm, 43.6mm
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Does OpenSCAD let you import photos so you can draw over them on another layer?
If so, and you have a copy of The GIMP installed:
1)photograph the underside of the RPi against a white background and pull it into the GIMP
2) Use the Perspective tool to correct for the camera not being perpendicular to the centre of the RPI PCB
3)Adjust the print scale so that the image prints at the correct size.
Now import the photo to OpenSCAD and use its tools to draw over the image and add dimensions if needed. Using the 3-point circle tool (assuming it has one) will accurately place circles over the mounting holes and you should be able to snap to their centres, which will let you add accurate dimensions.
If OpenSCAD can't import photos, print the photo and use a ruler on it while you draw a rough, dimensioned sketch that you can use to set up the CAD model.
Alternatively, if you own a vernier caliper or even a good steel ruler, why not use that to measure the RPi pcb, hole positions, etc? That should should be accurate enough. You can use the caliper or a set of drills to measure the hole sizes very accurately.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
Possibly... if that wasn't the spec for the old B model, not the 2B which was the model asked about.
The 2B has the same dimensions as the B+, with four proper mounting holes. Unfortunately I don't have the dimensions, but you could always measure one.
I have to wonder why you think that search will turn up anything RPi2B specific. There again I wonder why the OP doesn't just buy one and measure it - presumably he'll want one to stick in his finished project anyway.
This is one of many reasons why the rPi is not a good choice to use in any commercial product. It just is not specified enough to count on any aspect of it remaining constant over the life of a product it is used in. Of course you didn't say you were using it in a commercial product. In that case I would think the one accurate mechanical drawing available and your own measurements should suffice.
When I searched for this info I found the images were most important, so I did an image search. I found the heights of the top side connectors easily. The bottom side components were no so easy to find. Fortunately they were no so important to me.
They do bear this in mind (from the Pi2 launch blog entry)
"We have a lot of industrial customers who will want to stick with Raspberry Pi 1 for the time being. We?ll keep building Raspberry Pi 1 Model B and Model B+ as long as there?s demand for it"
Sure I did measure my Pi. But having a clear mechanical drawing is even better than all I can measure myself.
When my project is finished it will be best documented on my wiki page for everyone. There it would be nice if I can link to a drawing from all sides not only to the drawing from the top.
What I did was import photos into Inkscape, scale and orient them as appropriate, then draw over them. Export as DXF, include the DXF in OpenSCAD as a line, then extrude the path in OpenSCAD to make a shape. The resulting laser-cut output was pretty accurate.
(OpenSCAD is a description-based 3D modelling package - it's all code, there's no 'layers' or 'drawing')
Forgot to add, the first step in the process was to scan the hardware (not RPi related) using a photocopier that produced scale-accurate PDFs that could be imported into Inkscape with correct dimensions.
The main awkwardness was parallax - if things aren't planar then the depth makes the dimensions slightly inaccurate.
Which is why I mentioned using GIMP's perspective tool to correct for incorrect (handheld) camera positioning.
However, if you have the time, there's not a lot that can beat using a vernier caliper to measure dimensions and either that or a drill set for hole dimensions.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
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