Question about tuning heaters (M303)



  • Hi,

    I've got an extruder I want to test.

    It has two heaters which I have connected to two different heater outputs since I was concerned about putting too load on an output if I tried to connect both heaters to a single output.

    Can I use M303 to tune such a setup and if so how?

    Or do I have to control both heaters from one output?

    Thanks.

    Frederick


  • administrators

    @fcwilt how many Watts and what voltage are these heaters?



  • Hi,

    They are part of an XCR3D hotend - a Chinese brand I believe.

    They specs say they are 12v and 20w. The resistance of one I checked was 4.5 ohms.

    So if they are true 20w then in theory they would draw appx 1.6 amps so two in parallel would be 3.2 amps which is within the rating of the Duet.

    But if the 4.5 ohms is used for the computation then two in parallel would draw 5.3 amps which exceeds the rating of the Duet.

    That's why I played it safe and am tried to use two outputs but perhaps I am being over cautious.

    Frederick



  • @t3p3tony

    Your question got me to thinking I and dug out some from inventory and I think they one I am testing may have the wrong heaters.

    The heaters from these new ones are measuring 6.5 to 7.5 ohms so two in parallel would be fine on the Duet.

    But just for future reference is there anyway to tune a setup using two heaters on separate outputs.

    Thanks.



  • Are the two heaters attached to separate hot blocks or the same? Same temp sensor or separate?



  • @rcarlyle said in Question about tuning heaters (M303):

    Are the two heaters attached to separate hot blocks or the same? Same temp sensor or separate?

    For some reason the design uses two heaters and one thermistor for the one hotblock.

    I replaced the heaters with ones that matched the the heaters listed in the product description.

    They seem to be working fine - at least the "magic smoke" is still inside the Duet.

    Frederick


  • administrators

    The firmware does not currently provide for driving multiple heater outputs to control one logical heater.



  • @dc42 said in Question about tuning heaters (M303):

    The firmware does not currently provide for driving multiple heater outputs to control one logical heater.

    That is what I needed to know.

    Thanks very much.

    Frederick


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