OpenRPNCalc

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Open-source and open-hardware custom scientific RPN calculator

anton-poluektov

Anton Poluektov

1
3D printing the enclosure
Here are a few more-or-less random notes about 3D printing the calculator enclosure.
- I've printed it with the Creality Ender 3 V2 printer using PETG plastic, and the case went really well I think. Contrary to what's written in many websites, I've had no issues with PETG not sticking or sticking too strongly to the heated bed. My settings were: 235 C extruder, 80 C bed temp (85 C for the 1st layer).
- The top and bottom parts of the enclosure were printed without raft, directly on the glass bed, which made the nice and smooth surface. I've made a 4mm brim around them however, because I've had an issue with warping.
- The keypad and spacer were printed with a 4 layers, 4mm width raft, and I had to add dummy 1x1x1 mm cubes at the edges to simulate "mouse ears" to avoid warping (Cura slicer does not have "mouse ears" option). Since both parts are rather thin (the spacer has 0.2 mm, only one-layer-thick, springs) detaching them from the raft is tricky, but doable with a thin knife.
- I had an issue that the X and Y axes of my printer were not exactly perpendicular (about 1/2 degree off), which resulted in the top and bottom halves to be not exactly rectangular. And since the top was printed upside down, once the enclosure is assembled, it caused it to be bent in a propeller-like shape. I had to adjust the frame of my printer really well to make the case perfectly rectangular.

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