PT100 temperature variation when wire is touched

Discussion in 'E3D-v6 and Lite6' started by Sphere300, Mar 5, 2017.

Tags:
  1. Sphere300

    Sphere300 Member

    Joined:
    Mar 5, 2017
    Messages:
    2
    Likes Received:
    0
    I am currently using a reprap printer with the titan extruder and E3d v6 head with with a PT100 upgrade kit. I find that If I bend or touch the PT 100 sensor cable I get a wide temperature variation of 5-10 C. Note that I am bending it not more than 2-10 degree angles at most in order to see this. I can zip tie the cable to a position where it doesn't vary much during a print, but my question is whether this sensitivity is normal or if this is indicative of a broken PT100.

    Temperature Variation.png
    I have autotuned the hot end using the marlin auto tuning functions. The bed temperature is the correct in the attached picture and the PT100 can read exactly that but it needs to be in just the right position to do so. It seems to work best when the PT100 wire is sticking out exactly 90 degrees from the hot-end but that is hard secure in my setup and if If I leave it hanging in open air it will swing a bit as it prints.

    Please note that I picked up the PT100 sensors and upgrade kit from a north american distributer https://www.ultibots.com/
     
  2. Miasmictruth

    Miasmictruth Well-Known Member

    Joined:
    Sep 4, 2015
    Messages:
    758
    Likes Received:
    112
    Sounds like a broken wire, or poor termination of the wires. They are pretty fragile, I would try reterminating them. Make sure the wires are completely stripped at the termination.

    Also make sure you don't have and loose conductors strands that might be shorting the wire
     
  3. Sphere300

    Sphere300 Member

    Joined:
    Mar 5, 2017
    Messages:
    2
    Likes Received:
    0
    Ok that's a fair point.

    I removed the old connectors, and opted for a direct connection to the longer joining wire. This seems to have resolved the issue so I would suspect that the connectors were not mating correctly. As I am using a custom reprap It doesn't really matter to me that I am not using the provided connectors as long as it works.

    On a side note, I did notice the PT 100 wires are indeed a very thin single core wire, so I could see that breaking it if you handle it to roughtly.
     

Share This Page