An alternative to Kapton tape when mounting the thermistor

Discussion in 'E3D-v6 and Lite6' started by mundsen, Mar 5, 2014.

  1. mundsen

    mundsen Member

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    I have been using the Permatex Ultra Copper Silicone with great results.
    http://www.permatex.com/products-2/prod ... ker-detail
    Temperature range -65°F to 700°F (-54°C to 371°C)

    First I isolated the thermistor legs using PTFE tubes, then I added a small peace of aluminum foil to the hole before inserting the thermistor. In the end I added some of the Ultra Copper Silicone to keep the thermistor in place.
     

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  2. bmartensson

    bmartensson Member

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    Re: An alternative to Kapton tape when mounting the thermist

    Presently assembling a MendelMax and just getting to do the hotend.
    Question: Why can't I use the extra hole in the hotend for the thermistor?
    I have some 1.8 mm Teflon tubing and by stretching this I now have some lengths of < 1 mm dia tubing.
    Using this, the thermistor would fit perfectly in the extra hole.
     

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  3. Josh

    Josh Administrator
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    Re: An alternative to Kapton tape when mounting the thermist

    The heater-block has been a somewhat fluid design, and within v5 there have been around 5 sub-revisions due to us moving from Epcos to Semitec thermistors (and considering axials at some point in the meantime). The result of this is that there are blocks out there with different holes to their cousins (which has caused some confusion.)

    Every HotEnd that has been shipped with the correct hole for the supplied thermistor (and in some cases; extras).

    In the photo above uploaded by bmartensson, the hole indicated was intended to allow users to fall-back to an axial thermistor, however we do not really recommend using this hole since it is not as close to the nozzle as we would like and so does not provide the accuracy of temperature measurements that we would want for our customers.

    I really like mundsens use of silicone to seal in the thermistor - have you any install tips for anyone considering using it?
     
  4. mundsen

    mundsen Member

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    Re: An alternative to Kapton tape when mounting the thermist

    I did not take any pictures while mounting the thermistor, and I do not have an extra set to use for illustration images. But it is rather simple:
    -isolate the thermistor legs using PTFE tubes - get the tube as close to the thermistor as possible.
    - Before inserting the thermistor into the hole in the heater block I add some aluminum foil to the hole so I get a tight fit when inserting the thermistor.
    - cover the thermistor and hole using some of the silicone
    - let the silicone dry to the next day before printing

    The silicone stays soft, so I guess it is simple to remove the thermistor later using a knife to cut the silicone (not tested yet)

    I have not tested, but I guess the silicone can be used to cover the block to help isolate it? Like when using silicone tape?
     
  5. Eaglezsoar

    Eaglezsoar Administrator

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    Re: An alternative to Kapton tape when mounting the thermist

    You can use the RTV silicone to cover the block but it should not be necessary and IMHO the hotend looks better without it.
     
  6. bmartensson

    bmartensson Member

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    Re: An alternative to Kapton tape when mounting the thermist

    I did follow mundsens suggestion, works great - thank you!
    I used 2 mm heatshrink tube to lock the PTFE tubes in place after soldering the leads and then covered the whole bunch with another, thicker shrinktube. This greatly helped assembly. I did not use aluminum foil since the fit looked tight enough.
    Found a Casco 300°C Silicone, should be ok since I will not be printing any high temp stuff for now.
     

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  7. Eaglezsoar

    Eaglezsoar Administrator

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    Re: An alternative to Kapton tape when mounting the thermist

    Thanks for the pictures, very sharp and crisp.
    One hint on the use of the RTV is too add a small amount of cornstarch to it and mix it up then apply. It will set in
    approximately 30 minutes instead of hours. The ratio is roughly 10% cornstarch to 90% RTV. Experiment with it before
    using it on your parts. I think you will be pleasantly surprised.
     

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