3-D Printing/Softrock Enclosure

While helping KI6ZHD build his Softrock Lite II SDR (from KB9YIG), I ended up breaking the leads on my Softrock and we both talked about needing an enclosure for the receiver. We also talked about 3-D printing, which is something that sounds really cool. So this exercise is about designing an enclosure for the Softrock Lite II SDR that can be printed on a 3-D printer.

Preliminaries

I spent some time surfing web sites and reading tutorials where I learned that 3-D printing commonly starts with a solid model. There are a number of solid modeling programs and as long as they can produce STL files they will work with 3-D printing systems. I chose OpenSCAD which is available for Linux, Mac, and MS-Windows. While OpenSCAD isn't GUI based, the language is easy to learn and it was easy for me to enter values I measured from the parts that would be enclosed.

I found the OpenSCAD Tutorial Series at MakerBot to be a valuable and easy to understand resource.

I also found the Design Guide at RepRap useful when I was deciding on hole sizes.

As for dimensions for the Softrock Lite II, I would have measured my board, but it is on loan. So a query to the softrock40 Yahoo Group got me a response from the designer, Tony, KB9YIG. He provided the critical dimensions and I estimated the rest (like crystal height and location).

Requirements

The requirements are pretty simple. The enclosure will

• • house the Softrock Lite II RX PCB with all components mounted using the mounting holes designed into the PCB.

  • with mounting holes for:

    • a dual-pole PowerPole power connector.

    • a 3.5mm stereo jack.

    • a panel mounted BNC jack.

Procedure

I installed OpenSCAD which I configured for 'Automatic Load and Compile' so that I could use an external editor (Vim with OpenSCAD highlighting extension.).I set up a Git repository to track my work and practiced with some of the exercises from the OpenSCAD Tutorial Series.

I then built up the model a bit at a time. Sub-models for the Softrock PCB, connectors, and stand-offs are in separate files. The final model is shown at the top of this page. This cut-away shows the PCB and connector models and how they fit in the enclosure:

The enclosure model was cut in half to make a top and a bottom which were arranged side-by-side so that they can be printed at the same time:

The final step was to export the file (softrockEnc.scad) to STL. I don't have a 3-D printer (yet?) so I uploaded the STL file to i.materialize.com to see if it could be printed. There were no errors and I can print this enclosure in polymide for about $20.

Conclusions

The tools for 3-D printing, at least from a service, are ready for use; even on Linux. Once I discovered OpenSCAD this turned into a pretty easy exercise. It only took a few hours even though I had a lot to learn.

Other resources

While researching 3-D printing for this exercise I found a number of web sites that were of particular interest or potential future use:

Thingiverse - A Makerbot Industries web site for sharing 3-D designs.

Shapeways - A well known 3-D printing service.

Ponoko - Another printing service provides laser cutting and printed 3-D ceramics.

If you want to contact me about this exercise, look for me on Google+ (Jerry Dunmire) or use my call sign (KA6HLD) to send me mail @arrl.net.