Bed Compensation way off



  • Hi all, first time posting here and I haven't seen a "readme" post, so bear with me if I miss something.
    Anyway, I've been updating the electronics of my Tevo Tornado with a Duet. After much time with wiring, configuring and learning something completely new, I run a bed compensation command to see the magic happen. To my surprise I got a very large deviation for the first row of data points, which belong to the X axis. I don't have the numeric data in the computer I'm on right now, but I grabbed the screenshot (see below). The front row show a large deviation with a highest value of 1.6mm. I can tell you right now that such an uneven bed is visible to the human eye. The bed is a carbon fiber one on which I printed countless ours with great results using the old electronics. Before I run the bed compensation I adjusted the bed manually as good as I can. The sensor is a 18mm capacitive. I have a 12mm capacitive on a Prusa Steel running Marlin and I couldn't be happier. Also, I repeated the bed compensation twice more with comparable results... Any help is welcomed an appreciated.

    0_1549490631819_mesh.jpg


  • administrators

    It looks to me that you are probing off the edge of the bed in the -Y direction. Have you set up the correct X and Y offsets of the probe in your G31 command in config.g?



  • thanks, that was my assumption as well. However I watched the probe as it was sampling and it was definitely inside the bed. Actually the bed of the Tevo Tornado is quite longer than the print surface, so to say. In other words, when the nozzle is at Y=0, it is still about 2cm from the edge because of the screws holding it. I will play a little bit more with it though and report back.


  • administrators

    As it's a capacitive probe, it may also respond to metalwork to the side of it.



  • EDIT: original reply deleted because I went off-topic.

    It seems that both adjusting the grid and adjusting the probe height so the trigger distance is within 1mm helps to get a nicer surface... I now have a new issue, but I'll open another topic for that. Thanks!

    0_1549821476837_probe.jpg


 

Looks like your connection to Duet3D was lost, please wait while we try to reconnect.