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    looong journey with bltouch seems to have ended

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    • Tinchusundefined
      Tinchus
      last edited by

      I have posted another couple of posts about bltouch configuration and failures. I was never able to use it with some level of confidence. To sum up the other posts: my roblems were bltouch working randomly, sometime the probe is deployed a lot of time, sometime it is not. Sometimes there was a delay of like 2 seconds before being deployed.
      Answers to the problems were in general: this was a problem of noise and cabling, somethin g that of course I tried to adress but to me these answers were somehow "not ok" beucase they ignored my comments about me having already replace the cable 3 times, and even replacing the bltouch itself a couple of times.
      Any way, in weekends I continued to investigate the issue and now I have finally found a conclusion backup with real numbers and Im able to reproduce (and fix it) the problem.

      The problem is temperature. During config time and test time, I even executed like ten times, a script that deplyed the bltouch 100 times and I saw in person that happened, not failing a single time. And then lauched a print and probing was succesful. The another print and probing sometimes failed.
      I found the variable: material being printed and the material being used had a bigger bed temperature and hoter nozzle temp. And the important thing here: chamber. The printer has an enclosed chamber, not actively heated but really well closed. When printing PLA, interior temp never rises beyong 35 degrees celsius MAX,. But in the case of PLA or ABS, just preheating the bed to 70 or85 degrees, makes the chamber get to 55 degrees and more in case of ABS (65 degrees C)
      Also, even with heatblock being 12 mm away from the body of bltouch all these factors are enough to make bltouch body to reach a temperature between 55 and 63 degrees C. I have measure that using a thermocouple.

      I know that many will say that electronics are rated to handle 70/80 degrees with no problem. But this is real and it is happening. Ssomehow the temperaure affects the electronics and bltouch behaviour.

      This is not a cable problem: I changed cable 4 times. I remade the crimps like 10 times (all conection on my duets are made by me and they are like a total of 500 conections and I only had problem in 2 or 3 so I can say I know how to crimp a connector)
      I have tried 3 v3 bltouch and even 1 V2. And the problem in them were the same.

      f bltouch suceeds to complete the initial probing, what happends the is that randomly the pin gets down and up againg, like if there is some electrical noise. I have ruined like 7 pins so far.

      Today this idea come to my mind, and I did simple test. I made sure chamber was ambient temp and never more than 40 degrees. No problems at all, print sucessful, no pin up/down events.
      The I heated up chamber to 55 degrees 😄 in 5 times I tried, 3 of them had problem right in the beginning at initial probing, 2 of them were able to finish initial probing, all 5 times reported pin up/down events.
      Inmediately after 5th try, I cooled down chamber and also made sure bltouch was cool, and same gcode but with the chamber door opened and some extra small vent made all error desapear.

      So this is my comments about this in case somebody elase had seen this.

      Also a small report: M558 P9 C"io7.in" F100 H3.2 R0.2 T6000 A5 B1 , this command should turn off heaters while probing acording to docs in order to avoid noise, but it is not happening or at least on DWC heaters seems to be ON all the time while probing

      fcwiltundefined 1 Reply Last reply Reply Quote 1
      • fcwiltundefined
        fcwilt @Tinchus
        last edited by

        @Tinchus

        There are probes the use a simple micro-switch which should be fine in a heated chamber printer.

        But all of the ones I've seen need a way to mount/dismount the switch.

        I installed one called Euclid and it worked fine but that printer is no more.

        I've used inductive sensors but they seem to be less accurate than BLTouch units.

        Thanks for taking the time to document your experiences - everyone can learn from that.

        Frederick

        Printers: a small Utilmaker style, a small CoreXY and a E3D MS/TC setup. Various hotends. Using Duet 3 hardware running 3.4.6

        Tinchusundefined 1 Reply Last reply Reply Quote 0
        • Tinchusundefined
          Tinchus @fcwilt
          last edited by

          @fcwilt so far I got a tempral solution till I find a proper solution, I modified the start gcode to position the sensor out of printbed and so it doesnt get all the heat, I leave door open so chamber doesnt get hot. After probing I tape the pin to be sure it stays up, then close the door as soon as print start. LOL

          I looked for info and I found it: https://reprap.org/forum/read.php?1,873463,873463 reports something very similar. There are other similar posts on other forums too. and the nice find is:
          https://www.reddit.com/r/klippers/comments/102ycc3/bltouch_temperature_drift_over_time_seckit_cube/
          and pictures of the process: https://imgur.com/a/bJwce1D/

          Basically he reposts the same and his solution was to remove the electronics from bltouch body and take it to a cooler place doing a very surgical cabling work.
          I have still 2 working bltouchs so I might give a try to this project.

          Sorry for blameing duet electronics in the past!!!!!!

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