E3D Thermistor Cartridges Getting Updated

October 04, 2019

It's no secret E3D's thermistor cartridges could use an upgrade. And after receiving and analyzing feedback from customers about how their thermistor could be more robust and resilient to damage e.g. when a print fails catastrophically or during nozzle changes, E3D has heard you and is implementing 2 improvements.

What are they changing?

Cartridge Material

E3D has made the cartridge more robust by switching from a copper cartridge to a stainless steel one. This is not only stronger by having a greater resistance to over-tightening of the grub screw that retains the cartridge, but it also doesn’t oxidize as readily. This means the thermistor can be taken out of the HotEnd and re-inserted multiple times, without issue.

Multi-Stranded and Laser Welded Leads

In order to improve the robustness of the thermistor leads, E3D has introduced a flexible multi-strand cable between the Molex Microfit 3 connector and the thermistor itself. In their old design, the thermistor leads go directly into the connector (see below for old vs new comparison).

The multi-strand cable is thicker (therefore stronger), less prone to fatigue and less prone to insulation pull out than the single-core thermistor lead, giving a much more robust thermistor.

The joint between the multi-strand cable and the thermistor legs is achieved with a precise laser weld. This joint is fully encapsulated within the cartridge so only the multi-stranded cable is present outside of the cartridge and potting compound. 

Old Design

New Design

The following will NOT be changing

  • The thermistor element itself, still the same temperature table
  • The connector, this is still Microfit 3
  • The lead length
  • The price
  • When will this happen?

When will this happen?

E3D is currently running down their stock of old design thermistors prior to introducing the new design. They expect this transition to happen in the next couple of months. However, as of October 4, all E3D products sold by Filastruder that require the thermistor cartridge have been updated and will include the new design. 

Additionally, they previously had to be purchased the cable. Now, you can purchase with or without depending on your preference. Get them here.


Q: Is this a drop in replacement for existing thermistors?
A: Yes.

Q: Stainless steel is much less conductive than copper, surely this gives a performance decrease?
A: No, as the cartridge wall thickness is very thin it contributes very little to the responsiveness of the thermistor, from extensive testing we have found that it has no impact.

If you have any questions, please feel free to reach out through our contact page, and we'll be happy to help.


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October 21, 2019



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