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Replacing thermistor with glass bead type.  

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Maxiprint
(@maxiprint)
Eminent Member
Replacing thermistor with glass bead type.

Finally broke my thermistor on my MK3S. (bound to happen after 5 years of good service). My local suppliers don't have stock (neither does Prusa, for that matter).

Anyway, I need to print this weekend. I have PT100 glass beads and a E3D heater block for it. I hope it will work. Anybody used it?

Posted : 31/03/2023 3:24 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE:

On my old MK3 I have installed a PT100.

What you need:

- PT100 sensor, E3D Amplifier board ( https://e3d-online.com/products/v6-pt100-upgrade-kit)

- a small FW change

https://www.reddit.com/r/prusa3d/comments/cnw8dt/how_to_set_up_mk3s_mmu2s_with_pt100/

wbr,

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 31/03/2023 5:39 pm
_rob_
(@_rob_)
Eminent Member
RE: Replacing thermistor with glass bead type.

Any HT-NTC 100K will do.  You can get a 5 pack on amazon for like 10 or 11 bucks. I know that doesn't really help you this weekend but there are a ton in stock. I always keep spare thermistors and heater cartridges around for when I damage them changing the nozzle.

Posted : 01/04/2023 3:08 am
Maxiprint
(@maxiprint)
Eminent Member
Topic starter answered:
RE:

My apologies @karl-herbert.
I had my terminology wrong. It is not a PT100, but indeed a NTC 100K. @_rob_, I have that same 5 pack.
Looks like it will work. I replaced the Prusa block with the E3D block which have a smaller hole for the thermistor.
Quick check on low temperatures with the hot end not fitted, shows it is working.

(And thanks to ChatGPT for telling me what the difference is. 😀 )

Posted : 01/04/2023 10:58 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Replacing thermistor with glass bead type.

The NTC-100 is a universal thermistor, which is used in many types of printers. Important is the internal resistance at room temp. of 100 kohms. Should work fine with the Prusa Mk3.

However, there is a possibility of temperature deviations of a few degrees C., since the different 100k types have different temperature curves.

wbr,

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 01/04/2023 3:11 pm
Maxiprint
(@maxiprint)
Eminent Member
Topic starter answered:
RE: Replacing thermistor with glass bead type.

I've installed it and tested it.
Did PID calibration as well as Thermal Movement calibration.
Also upgraded the firmware.
Temperature stays spot on.
I haven't printed yet. Still busy with a major overall service on my 5 year old machine. But all indications so far tells me it should be fine.
Thanks for your help. Alles klar. 👍 

Posted : 01/04/2023 8:04 pm
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