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K-type thermocouple on UM2


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Posted · K-type thermocouple on UM2

Hi all;

I'm trying to get an Ultimaker 2 to print at temperatures up to 450°C for testing with PEEK.

I've got a v6 hot end and a 40W heater installed, and I've modified the firmware to allow these temperatures; the issue I'm having now is with the PT100B sensor; it seems to be failing at temperatures below 400°C.

So I am looking to install a k-type thermocouple; I have this thermocouple:

http://e3d-online.com/Type-K-Thermocouple

and this amplifier board:

http://e3d-online.com/External-Thermocouple-Board-v1.0

but I have no idea how to get them connected and working with the UM2.

By any chance does anybody know what I should do?

Or is there another solution you might recommend?

Thanks, Mike

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    Posted · K-type thermocouple on UM2

    I don't know of a solution to date.

    Off the bat you would run into a range of issues, like:

    1. The Ultimaker 2 hardware is designed for Pt-100, with electronic components to compensate for the characteristics of the Pt-100. Since the Thermocouple has a completely different output levels, you would need a separate amplifier. But you would have either to bypass the compensation circuitry on the UM2 mainboard or simulate the behavior of the Pt-100.

    2. The thermocouple would have to be isolated from ground. A ceramic insulator would suffice.

    As a solution, I would try to replace the existing Pt-100 with a ceramic one suitable for high temperature. In the process industry Pt-100's are successfully used up to 500 deg C.

    I would like to know how you plan or succeeded in getting the hot end to work at these temperatures the ptfe insulator would certainly fail.

    Hope this helps.

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    • 2 weeks later...
    Posted · K-type thermocouple on UM2

    I don't know of a solution to date.

    Off the bat you would run into a range of issues, like:

    1. The Ultimaker 2 hardware is designed for Pt-100, with electronic components to compensate for the characteristics of the Pt-100. Since the Thermocouple has a completely different output levels, you would need a separate amplifier. But you would have either to bypass the compensation circuitry on the UM2 mainboard or simulate the behavior of the Pt-100.

    2. The thermocouple would have to be isolated from ground. A ceramic insulator would suffice.

    As a solution, I would try to replace the existing Pt-100 with a ceramic one suitable for high temperature. In the process industry Pt-100's are successfully used up to 500 deg C.

    I would like to know how you plan or succeeded in getting the hot end to work at these temperatures the ptfe insulator would certainly fail.

    Hope this helps.

     

    Hi Daedalus;

    Thanks for your reply!

    I got the thermocouple working, and now can measure as high as the heater is going to, about 400°C; I'm still hoping to get another 30-50° out of it with a bit more modification!

    To answer you question about the hot end: I installed the E3D v6 all metal hot end; it seems to work fine at the higher temps, would recommend it.

    Thanks again,

    Mike

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    Posted · K-type thermocouple on UM2

    Hi Mike,

    Thanks for the tip, I've looked into the E3D hot end and that looks good.

    Isn't it easier to install a separate temperature control with it's own power supply? Then you can use the higher voltage heaters and reduce the current.

    How did you manage to connect the thermocouple?

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    Posted · K-type thermocouple on UM2

    Hi Daedalos;

    Forgive the late reply. Here's notes adapted from my findings in adapting the UM2 for PEEK:

    Thermocouple Installation:

    Add the AD597 amplifier and conditioner unit into the main board as shown in the attached figure:

    Thermo_um2.jpg.bdcadcefa0afa21d994f5282810581dd.jpg

    Then alter the firmware to recognise the input as a K-type thermocouple and to reassign the pin for the new location of the sensor input. The code below refers to the type of sensor used for the hot end temperature measurement, and is located in the Configuration.h file:

    #define TEMP_SENSOR_0 20

    where TEMP_SENSOR_0 is defined as the hot end sensor, and the number following it, in this case a 20, refers to the sensor type used as stated below:

    //// Temperature sensor settings:

    // -2 is thermocouple with MAX6675 (only for sensor 0)

    // -1 is thermocouple with AD595

    // 0 is not used

    // 1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)

    // 2 is 200k thermistor - ATC Semitec 204GT-2 (4.7k pullup)

    // 3 is mendel-parts thermistor (4.7k pullup)

    // 4 is 10k thermistor !! do not use it for a hotend. It gives bad resolution at high temp. !!

    // 5 is 100K thermistor - ATC Semitec 104GT-2 (Used in ParCan) (4.7k pullup)

    // 6 is 100k EPCOS - Not as accurate as table 1 (created using a fluke thermocouple) (4.7k pullup)

    // 7 is 100k Honeywell thermistor 135-104LAG-J01 (4.7k pullup)

    // 8 is 100k 0603 SMD Vishay NTCS0603E3104FXT (4.7k pullup)

    // 9 is 100k GE Sensing AL03006-58.2K-97-G1 (4.7k pullup)

    // 10 is 100k RS thermistor 198-961 (4.7k pullup)

    // 20 is PT100 with INA826 amp in Ultiboard v2.0

    which means a change in the sensor from the PT100 to the Thermocouple with an AD597 amplifer requires the change

    #define TEMP_SENSOR_0 20

    to

    #define TEMP_SENSOR_0 -1

    as the AD597 is equivalent to the AD595 for this purpose.

    Pins on the Main Board now needed to be reassigned via the firmware as the thermocouple sensor was now connected differently from the PT100 connector. The file pins.h designates the pins on the main board according to the type of board used.

    In configuration.h the main board is defined as:

    // 72 = Ultiboard v2.0 (includes Ultimaker 2)

    within the Ultiboard v2.0 section in the pins.h file the temperature sensor for the hot end is defined as:

    #define TEMP_0_PIN 8

    Now the temperature readings are being fed via the thermocouple into the pin assigned as 0 on the main board and so the code is changed accordingly:

    #define TEMP_0_PIN 0

    Once you upload this code the Thermocouple should provide temperature readings for the hot end.

    Thermo_um2.jpg.bdcadcefa0afa21d994f5282810581dd.jpg

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