Disabling Thermistors

I'm making a bioplotter from my Mendel. Which means I don't need the hot end or the extrusion assembly anymore as I'll be replacing them with a rudimentary syringe pump, simply extruding a liquid albeit viscous scaffold material onto a surfacing containing its crosslinker. Of course, removing the thermistors throws up an error. Now, I see how to change the settings of the thermistors depending on the type and calibration. But I'd like to see the best way to set them to "not present". Neither the hot bed nor the hot end need a thermistor since I don't plan on using either, but the the hot end thermistor is the main one I'd like to remove completely.

Anyone know what to set it to?

In Marlin's Configuration.h, set all thermistors to 0:

#define TEMP_SENSOR_0 0
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_BED 0

I've not tried it, but it should work. You may also need to enable cold extrusion. which you can do by sending M302 to the printer.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Yea, I use M302, though if there's a neat line or two I could alter to avoid having to do that each time that would be nice.

Added those lines in didn't affect the outcome. Still throwing the same error. Has anyone successfully done this?

What error gets thrown?

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Just stick a permanent resistor of the appropriate value in the circuit.
If you've got a plug/socket arrangement you can even connect the resistor to the syringe and use that as a kind of "head detect" mechanism.

The error I receive when disconnecting the thermistor or attempting to extrude.

Error:0
: Extruder switched off. MINTEMP triggered !
Errorrinter stopped due to errors. Fix the error and use M999 to restart!. (Temperature is reset. Set it before restarting)


Extruding 5.000000mm of filament.
Printer stopped due to errors. Fix the error and use M999 to restart!. (Temperature is reset. Set it before restarting)


If anything, I could reattach the thermistor in a way that will keep it out of the way before finding another component to use in its place. I have considered even just keeping it attached to where the syringe is kept, as mist42nz suggested, as a way to monitor the temperature of the ambient temp. around the cell-loaded media during printing. But, I thought I should try to see if there was a more elegant solution first. At least until the printhead is redesigned.

Thanks for your suggestions and any further help.

Try commenting out line

#define PREVENT_DANGEROUS_EXTRUDE

in configuration.h