Precision Piezo Andromeda



  • I've mounted four of the andromeda sensors under bed on my D-BOT. using the P20 V1.1 controller plugged in to the Z probe socket on my Duet Wifi motherboard, and gconfig as prescribed. I have to bang the heatbed really hard to get a reaction. Afterwards I did some testing with a lab power supply set at 3.3v, and it worked flawlessly when I tap the bed, the blue led did light up, and it was easy to adjust sensitivity. The wires was at the same length. And the messured v output from the board was the same as from the lab psu. I'm stuck here, anybody any suggestions?



  • I'm using this configuration and I'm not having problems anything like what you describe.

    Try with just the VCC and GND connected to the Duet.



  • @SupraGuy I am about to try this on my DBOT can you send me a picture of your sensor mounts I am looking for inspiration.



  • @adam2070 The purple thumbwheels have a 3mm nut embedded in them. The screws through the bed are secured to the heated bed with nuts, and "float" through the bar. Basically, the bed is standing on the Andromeda sensors, so any pressure on the bed is transmitted to the sensors.

    I mounted them to 3/4" aluminum tube, because the existing frame for my printer is acryllic, and I needed extra rigidity to make the sensors work well.

    This is pretty close to at least one of Irdis' example drawings.

    0_1549638316656_20181002_201833.png 1_1549638447029_Andromeda_exploded.png 0_1549638447029_Andromeda.png



  • @supraguy I'm suspecting interferens on the wires to the piezo elements, where have you mounted the P20 card?



  • @adam2070 This is how I have made the mounts for the Andromeda on my D-Bot:1_1549654192635_fester.JPG 0_1549654192635_Feste.JPG



  • From that picture I can't see what puts pressure on the Andromeda board. I will assume that there is a spring between the Andromeda board and the heat bed, with the thumbwheel there to adjust the bed's height.

    The general intent of the Andromeda boards should be that the ends are mounted rigidly to a frame, while the centre takes pressure from the nozzle. I opted not to use a spring with my mount solution, because nozzle pressure applied via a spring seemed like it would be less reliable, certainly muted by the spring's compliance. So in my case, the height adjustment thumbwheels are captured between the frame and the Andromeda boards, and determine the build platform mounting height with no springs involved. Any pressure upwards just holds the thumbwheel to the frame, so the bed does not lift out. Any pressure downwards is transmitted directly to the Andromeda boards without being reduced or buffered by a spring.



  • The thumbwheel are only for securing and fastening the bed. I've used printed distance bits between the Andromeda and heatbed :
    0_1549707263046_Heatbed distance part Andromeda v1.jpg



  • Thanks for the inspiration. When I have time to design something i will make sure i post it.


 

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