PT100 failure lesson learned



  • I have been finalizing the hot end layout on my upgraded Ender 3. I finally got the Prusa mk3 fan nozzle adapted, but somewhere in the process it's apparent that my new PT100 sensor failed. It wasn't apparent to me after 4 hours of troubleshooting, after perfect printing turned to absolute crap. Fortunately I could rob the PT100 from my CoreXY. Printing has returned to some of the best I have seen on my bench. What had happened was the reading was not dead, but it was far enough off that the hot end never reached the range needed for printing. Maybe I over tightened the set screw, but it looks the same as the one that moved from the other printer. I guess the lesson is not to trust any numbers unless you can verify them in some way. In my case I have an IR gun that doesn't read anywhere close to right, but it started me thinking. Then I noticed the temp was like 35c at ambient. OOops.


  • administrators

    Temperature inaccuracies when using PT100 sensors are usually caused by poor connections. Each ohm of resistance in the connections or the cable will increase the reading by about 2.5C. I have this problem on one of my own printers at present, I can make the reading change by more than 10C by waggling the cable close to one of the connectors.



  • @dc42 said in PT100 failure lesson learned:

    Temperature inaccuracies when using PT100 sensors are usually caused by poor connections. Each ohm of resistance in the connections or the cable will increase the reading by about 2.5C. I have this problem on one of my owm printers at present, I can make the reading change by more than 10C by waggling the cable close to one of the connectors.

    Hmm, well I swapped with my other PT100 sensor and printing was transformed back to normal? I ordered another one tonight. Once I have 3 I may mess around with them.


 

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