Thermistor for 275 Celsius

Hi,

I am learning to print carbon infilled, nylon filament (https://markforged.com/product/onyx-filament/) on my custom designed multi-tool machine that is driven by Marlin bugfix-2.0.x firmware.
This filament is printed at 275 C on original Onyx One printer.
I have configured new all-metal hotend (actually separate direct drive extruder) with rather expansive E3D titanium heartbreak, heated block and nozzle components. I had to even upgrade stepper to get more torque.

I finally made my first successful print, but I had hard time keeping 275 C at check.
I have used NTC 3950 100k thermistor (from aliexpress) - Marlin type 11. Depending where you read, these thermistors are usable to up to 250 C while others saying 300 C.
At 275 C it fluctuates a lot, to the point where I had to increase Marlin temperature hysteresis from 3 degrees to 6 to prevent thermal protection error condition.
And yes, I did PID calibration many times.

Do you guys know if there is an inexpensive thermistor that is known to be good at 275 C?

Thank you!

PS. Please see attached pictures.

The thermistors sold by E3D are rated to 300C.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

... I've tested PT100 sensors for up to 600°C

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Quote
dc42
The thermistors sold by E3D are rated to 300C.

You are most likely correct.
Now I feel bad because I gave away my Titan with original hot-end.
I will buy one I guess.

Thank you for pointing it out.

I was hoping that someone could confirm the actual temp range of NTC 3950 100k sold in China and elsewhere in US.

Edited 1 time(s). Last edit at 11/05/2019 11:29PM by uticatechclub.

_

Edited 1 time(s). Last edit at 11/06/2019 12:19AM by uticatechclub.

Of course its in Marlin, with 3 different ways to connect it...


20 : the PT100 circuit found in the Ultimainboard V2.x
147 : Pt100 with 4k7 pullup
110 : Pt100 with 1k pullup (non standard)

... the lower pullup will give more resolution, so more accurate readings.

I've used "amplifiers" to get higher voltage and sensing ranges ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thank you all!

I ended up ordering couple of E3D thermistors and will check how they behave at 275 C.
E3D Thermistor