{240713}
I'm cutting the second plate for the second node of the first reticule. I'm using the Snapmaker matte black acrylic 290 x 290 x 3 mm plate, the node's board is 178 x 202 mm; I'm marking the acrylic with a hand drill at (100, 110) mm from the left-top, then removing the protective sheet, then marking the drill mark with a white paint marker. The plate is attached to the Snapmaker so that the right side aligns with the platform, the bottom side aligns with the front-most hole of the platform. This gives a work origin of approx. (135.5, 197) mm. I'm using the automatic thickness measurement that yields ~2.6mm, and cutting with a work speed of 60 mm / min (this is half of the default speed for 3 mm acrylic, but I found my 10W laser has slightly degraded performance, so this one makes sure every cut is well done).
{240818}
For the “weave” reticule. Initial size 18 x 9 = 108 slides and piezos; glass slides are 70.0 x 74.2 mm; metal wire frame. Piezos will be wired in parallel, so there are two pairs of twisted cables on each. The cable lengths are 100 and 105 mm for each twisted pair. They go to a male and a female JST XH 2.54mm connector. Former "black wire" of JST (to be removed) specifies "gnd" or brass part of the piezo. We isolate with d = 0.8mm shrink tube, 8 to 10mm length. The JST has be soldered while plug and socket are connected, otherwise the pins move due to the plastic melting.
{240713}
The acrylic plate (per node) is equipped with
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4x "feet" M3 black acrylic spacer,
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3x TPA3110 based stereo-amplifier circuit boards, with 7.62mm screw terminals for output and power, a mini-jack socket (Rean NYS 240 BG) soldered with a ~6cm cable to the line input; using 2mm MDF shims as "feet", and M2.5 screws with hex head. Their power input is chained, using the red and green AWG 22 wires of a three-pin 'LED wire'.
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1x Logilink UA0099 audio-interface with housing removed, and jack sockets painted black. A black shrink tube dims the blue led. The connection to the amplifier is done through three 10cm long 3.5mm jack cables. The USB connection uses a 25cm USB cable (Goobay 95129). The interface is lifted by four 30mm M2 screws with fixing nuts.
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1x Raspberry Pi 4B, 4GB with only top-part of black "armour case", lifted with four white 20mm Nylon M2.5 spacers/screws.
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1x DC Buck / step-down converter 12V to 5V with screw terminal and barrel input, and USB-A output, e.g. this. The board is fixed with plastic ties (12 cm x 2 mm), using two pairs of holes in the acrylic plate. The screw terminal "input" is passed to the amplifiers (c. 17cm red/green AWG 22 wire). The USB output is passed to the Pi using a 15cm or 30cm cable (depending on the orientation of the node). The power is given by a Leicke 90W supply, using the 2.1mm adapter.
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A metal push button with ø 12mm mounting hole, two wires connected with JST to the GPIO pins GPIO5 (Wiring Pi 5, BCM 24) / GND (header 18, 20).
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A PIR (passive infra-red) sensor is attached with two 30mm M2 screws with fixing nuts. A custom cable is made from a 5-pin JST connector that sits on the GPIO using 5V, GND, (NC), (NC), GPIO1 (Wiring Pi 1, BCM 18) (header 4, 6, 8, 10, 12). On the recommendation of someone from the Internet, a 330Ω resistor is inserted on the data wire, although so far my measurements have shown that the trigger is never above 3.3V. The cupola is painted black with a glossy laques pen.
