Thermocouple'd Nozzle

Compact module with direct nozzle temperature sensing

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My biggest headaches with 3D printers so far have been related to the hot end temperature sensors. Be it poor contact with the heat block, open circuit failures, short circuit failures, limited temperature range...

Even when everything is working perfectly, since the temperature sensor is measuring the heat block/spreader and not the nozzle itself, there is always guesswork/tweaking to get things working like they should.

My solution is to weld a thermocouple directly to the nozzle itself - eliminating all of these issues. And don't worry about the supposed poor accuracy of thermocouples, this is just an offset that can easily be measured and accounted for.

All design details will be made available - My goal is 100% open source and open hardware.

Without the need to attach a temperature sensor to the heat block/spreader, much more compact options become available, I have selected a cylindrical ceramic heater to provide even, concentric heating of the filament. 

  • 1 × Thermocouple Wire - 6 inches K-Type, Kapton insulated (400 °C), single solid strand, AWG 24
  • 1 × Fiberglass Sleeving ~ 1.5 inches 1mm ID, 2mm OD, rated to 600°C
  • 1 × Heat Shrink tubing ~ 0.5 inches From an assortment kit
  • 2 × Crimp Ferrules From an assortment kit
  • 1 × Stainless 0.4mm nozzle

View all 8 components

View project log

  • 1
    Nozzle Assembly Components
  • 2
    Thermocouple preparation
  • 3
    Closeup of balled and flattened thermocouple wire ends

    I find that a 14 to 15 Joule pulse weld gives the best results. The welder is an Orion model 100c micro pulse TIG welder.

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skrogh wrote 11/16/2021 at 15:21 point

Ah I love the way you implemented the heat shield / "sock"

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Charles Cordiez wrote 06/13/2018 at 09:38 point

Neat ! Which cylindrical heater adapter are you using ? 

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skrogh wrote 11/16/2021 at 15:24 point

It looks like the heater from the deltaprintr mini.

TriangleLabs also sold these for a while, but have discontinued the aluminium version.
They sell one with copper "core" (threads) now, but that one has the "nut" towards the nozzle with space for a thermistor.
Both are (were?) 24v/50W.

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