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Extruder nozzle heater - possible ‘alternative’ approach?

Posted by NumberSix 
Extruder nozzle heater - possible ‘alternative’ approach?
February 17, 2011 06:25PM
Extruder nozzle heater - possible ‘alternative’ approach?

Hi folks, (have done a bit of searching and can’t find any similar discussion – forgive me if I’ve missed it).
I have a little glue-gun that appears to heat the nozzle by powering, what actually look like ‘thermistors’ that are embedded directly in the nozzle ( I know!... usually associated with controlling temperature, not generating heat). You’ll have to see the photos to more clearly understand what I’m talking about, so have a look.

The spring-like wrapping around the black tube is structural, holding the orange tube in place. There are no electrical wires attached to it.

I appreciate the temperature range required for a RepRap extruder is well above my little glue-gun temperature, but I’m interested in the nozzle heating concept employed. Can anyone identify the heating component and comment whether there is potential in this approach to reach temperature ranges required to run a reprap extruder?

I have taken electrical measurements and can provide the following additional information:
Resistance across one of the ‘thermistors(?)’ = 4.8 milli-ohms(Reasonable reading?) @ 19Dec C. I de-soldered one of the wires to the ‘thermistor’ to take this reading.
I heated the ‘thermistor’ by touching the soldering iron off it for a short while, and the resistance increased to 5.1 mili-ohms (wouldn’t seem to go any higher than that.)
What type of ‘thermistor’ does that make it? PTC thermistors?
I measured the Current flow through this component with the glue-gun switched on and heating up. It started with .4amps, then dropped over a minute or so to .36amps stabilizing at that reading.
The voltage across the 4 batteries reads 5.5V. The voltage across the ‘heater’ when it’s wire is soldered back in is 5.1V.
That makes each heater = 2 Watts (5.1volts x .4Amps). With two heaters in the brass nozzle, it gives it a 4 Watt rating? Reasonable guestimate?

Do you think the heating concept has potential? i.e. Find/make a brass nozzle, embed multiple heating components (what ever they are - suitable ones!) directly in the nozzle shoulder, add some temperature control perhaps?

Re: Extruder nozzle heater - possible ‘alternative’ approach?
February 18, 2011 03:16AM
Hi No.6,

... you have to search with "all dates" - here is a search with "glue-gun" and "VDX" as author ...

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