Stock Taz 6 Thermistors

I am completely fed up with the delicate nature of the existing stock thermistors.

Does anyone have a step-by-step method of what is required to move away from these things to something better? Part, source, how to modify printer settings?


Changing thermistors could require re-compilation of the firmware.

Which thermistors are you having problems with?

The 100k Semitech GT2 ones that Lulzbot puts on their stock hotends. Either I am very heavy handed and keep breaking them or they get the wires crossed or they ground out on the hot end. Either way it is a PITA to keep putting everything back together only to find it does not work at all or it stops in the middle of a print.

To me it looks like the ones at E3D are superior from the perspective of mounting and being robust. But I don’t know about their electrical properties.

No crimping - that’s the nice thing about the new cartridge thermistors. They are precrimped with pins that work with a molex/JST type connector. Not sure if they work with the hexagon single extruders… but I’d bet they could.

Do the E3D ones require any firmware changes or just changing the electrical and mechanical attachments?


I’m not a firmware guru, but I believe they are a different type of thermistor and require a change.

I you order the E3D hotted for the Taz 6 will come with the correct thermistor in a potted brass cartridge.

I went to thermocouples on my hot ends (all E3D) - indestructible and you can make them yourself - just need to get the converter board and wire it up to a spare analogue input pin and change a few values in the firmware. I’ve had several thermistors go wonky for no reason - they are by nature very delicate.


John, thanks for that. Is there a place to begin learning how to make the firmware changes necessary? I’m not really intimidated by it, just don’t know where to even start!


I was too - you really just have to dive into it - I can help you configure the FW for a thermocouple - it’s actually very simple and you always have your back up stock FW to fall back on.

You need to get the E3D amplifier board and wire it to 5v+ and ground on the controller board - this thing here:

Then in the FW you just change the pin number for the temp 0 (extruder) to the pin you’ve plugged the analog output from the TC board to and the temp pull-up table for a k-type thermocouple - I’ll walk you through it… literally takes 1 minute to edit the FW for this and you’ll never have to worry about a sensor failure - you can beat a thermocouple with a hammer and it will still work.

The other issue with thermistors is that they are dependent on the input voltage being perfectly correct which of course can vary slightly depending on how well the voltage is controlled on the controller board etc etc.

I can make you a k type thermocouple and test it to verify that it’s perfect if you don’t know how to make them. The problem with buying one is that the leads are often too short and you need to have K type TC alloy wire going all the way to the amplifier board unless you want to get into gold contacts - basically you don’t want any TC to non TC crimp or solder connections between the actual TC and the board - it can throw off the temp values although in practice and from my testing it’s negligible.



Thanks again for your generous offer to hold my hand through this. I will go ahead and order the part and at least get that far. Was thinking about PMing you, but I suspect I’m not the only one that can benefit from the rest of this process so I’ll update this thread when I get that far.

You should try the Lulzbot cartridge thermisters first… A lot less hassle than having to deal with an external board, IMO.


I might give this a go as well. If I read the details found at your link for the new thermistor it says to use “Table 5” in firmware.

I went to the Development site at Lulzbot and found that for the firmware I am using FlexyDually V2 that it seems to show the thermistors being referenced to this already??

#define MACHINE_UUID “845f003c-aebd-4e53-a6b9-7d0984fde609”
#define EXTRUDERS 2
#define POWER_SUPPLY 0
#define TEMP_SENSOR_0 5
#define TEMP_SENSOR_1 5
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_3 0
#define TEMP_SENSOR_4 0

Bearing in mind I have no idea what I am doing in the firmware nor exactly how to change and recompile it, what do you think? I wonder if its worth a try to just plug in and run with it…


You found the right resources to re-program the firmware to support the E3D thermisters.

Have you compared the Aerostruder’s configuration.h file to the stock Taz6 tooolhead? If the thermister values are the same, then it should be okay to use as long as the copper cylinder fits in the hotend…

I dug out my old single toolhead that came with my TAZ5. The new cartridge thermister will not fit in the hexagon block… so you may be back to working with the glass thermister. See attached…

You shouldn’t have to do anything to the firmware if you order the correct thermistor (Semitec 100kOhm).

The Taz 6 uses the same Semitec thermistor as the one that E3D supplies with their hot ends unless otherwise specified.

I’ve had both the Semitec and PT100 RTD’s fail BTW… and the way they fail is annoying - the temp reads right but is cooler than indicated - so you start having issues with layer adhesion etc then finally your extruder jams because it’s reading right but is too cool to melt the plastic.

Wiring up the little amp board is simple and changing the pin and temp tables in the FW is also simple - up to you - I can make you a K-type TC potted in a brass cartridge if you want to try it out - no charge.