Setting temps beyond the thermistor table.

I haven't used Marlin in ages, and never had cause to push high temps when I did, but the question came up recently..

How does Marlin handle it when an operator sets the nozzle temperature higher than where the thermistor table ends?

I've seen people claiming to be running up to 325C with a glass bead stock from China printer, but when I looked into it, the thermistor tables I opened (2.0 bugfix) topped out at 300C with only the 1 Ohm/719C reading being higher.
Where is the 325C reading on the screen coming from?
Is Marlin extrapolating?
Is Marlin setting to the 300C and just reporting 325C?

Perhaps I wasn't looking at the right tables, but still would like to know how Marlin would handle this scenario.

Thanks all!

Most Thermistors can't do high temp.

Most high temperature is done with thermocouples and maths not tables.

Edited 1 time(s). Last edit at 03/01/2020 12:10AM by Dust.

... was using PT100 both, for sensing, and as small heaters with upt to 600deg -- but then I had to change the maxtemp-values too ...

---

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

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

Yeah, I've used E3D's PT-100 & amp board on an Azteeg smoothieboard for the last 3 years, and I know where it's limits are, but that's why I cannot test for myself.

I was just wondering what Marlin would do if you set temp higher than the thermistor's table (assuming they've changed the max_temp).
I've seen a couple tables top out at 300, but this is the second time I've seen someone say they're printing higher without anything special.. wondered what was really happening. Does Marlin tell tall tales??

Edited 3 time(s). Last edit at 02/29/2020 08:46PM by Diggrr.

... you too have to modify the tables or replace the temp routine with own code -- with PT100 it's easier, as the curve is nearly linear

---

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

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