Injection molded enclosure v1

Bus Pirate 5 has 16 RGB LEDs (and just one button!) and is intended to go in a transparent/translucent case. I printed the initial cases in PETG with a Prussa Mini, and last week we send the final version off to Dirty PCB’s SLA supplier.

The fit wasn’t quite right, about 0.2mm gap where the shell meets. We made three modifications to test: +0.2mm PCB spacing, +0.2mm LCD spacing, and one with both. Using a bare PCB in the enclosure pretty much confirmed there is a small PCB spacing issue. These prints went out Thursday, we would have tested on Friday but deliveries were canceled because of the typhoon.

After confirming the fit, and honestly I’m happy as it exists now, we’ll open up tooling with the mold manufacturer. It’ll probably take at least a month until we have samples. We’re having the mold made for PP material, and we can choose a tint for the translucent effect (smokey grey maybe?).

1 Like

I don’t know if something went wrong with my SCAD script, or the SLA, or what, but V11/12/13 all seem to have been a step backwards from V10 in various ways. Looks like V10 is the winner, we’ll start the mold today.

I used openscad to make the case model because I really like adjusting the parameters and rebuilding the model as needed. Clicking around in a CAD UI to make fraction of a mm changes really frustrates me.

However, the step file I exported from openscad via freecad doesn’t work for the tooling people. I used fusion360 to rework the mesh and convert to a solid, but that still wasn’t working. Nobody really told me why or what they need, communication has been lacking throughout this experience.

The upshot is that we hired a designer to redo the model in solid works. I’m pretty frustrated that I don’t know why my step file was unacceptable, but I’m begrudgingly accepting that this is the right work flow. I can do my little designs in my bespoke app of choice, and then hire a professional to make the tooling version. To be fair I half expected the tooling people would do the design in their own software anyways, but the way it all went down was chaotic, confusing and wasted half a day for three people.

The tooling is started though, at least I think.

Finally! We have plastic! Injection molding is a slow and fraught process :slight_smile:

Here’s two material samples.

The left is polypropylene, the material used in milk caps. It’s really cheap and really clear. The sample color doesn’t diffuse the LED light much, but it’s grown on me as I’ve used it.

The right is polycarbonate, a much harder and more expensive material (twice as much as PP). The sample color is a little too opaque though. There are ‘hot spots’ over the LEDs, and dark spots where the light doesn’t carry as well. I think we’ll ask for another sample in PC that is slightly less opaque.

Any thoughts?