Thermistor selection Marlin 1.1.8

I have a SEMITEC 104NT-4-R025H42G screw in type thermistor on my hotend.

I dont see that on the thermistor table to select so I used type 5 104GT-2 with Marlin 1.18

Googleing about a bit I am pretty sure they dont have the same curve.

I was wondering if there is a way to use the Steinhart Hart algorythm to input the curve as I have found all that data:

104NT-4R025H42G

I for Steinhart Hart 0.000797110609710217F
J for Steinhart Hart 0.000213433144381270F
K for Steinhart Hart 6.5338987554e-08F

Thanx in advance

Edited 1 time(s). Last edit at 12/27/2017 12:27PM by JustSumGuy.

8 bit machines to slow to do the maths real time.... thus they use tables

you can generate your own table see [github.com]

ok, that looks like it will take some learning

If you generate (and add) a table... Try to be smart about the range of values and the spacing. Marlin does a sequential, linear search from the end of the table. So just a few values at the higher temperatures. And then some closer spacing of values near the normal print temperatures.

Can anyone lend a hand? I know zip about python.

I have installed "IDLE" and cut/pasted the script from that link into a file but when I tell IDLE to check module via ALT-X I get a syntax error ?!?

see attached snip plz

Thanx

P.S. useing IDLE ver 2.7.14 I will install and try ver 3.x now tho....

Edited 2 time(s). Last edit at 12/31/2017 06:55PM by JustSumGuy.

Tried Python 3.6.4 and got a different error.



This error when I research it makes me think that I should be using Python 2 but that loops me back to the first issue with Python.....

Edited 1 time(s). Last edit at 12/31/2017 08:55PM by JustSumGuy.

Ok, started from scratch on a different PC and it worked.

now I am lost at how to input the data I have been able to glean from Google into this script...

104NT-4R025H42G

I for Steinhart Hart 0.000797110609710217F
J for Steinhart Hart 0.000213433144381270F
K for Steinhart Hart 6.5338987554e-08F

The script as far as I can tell is looking for this info:

t1 = 25 # low temperature in Kelvin (25 degC)
r1 = 100000 # resistance at low temperature (10 kOhm)
t2 = 150 # middle temperature in Kelvin (150 degC)
r2 = 1641.9 # resistance at middle temperature (1.6 KOhm)
t3 = 250 # high temperature in Kelvin (250 degC)
r3 = 226.15 # resistance at high temperature (226.15 Ohm)
rp = 4700; # pull-up resistor (4.7 kOhm)
num_temps = 36; # number of entries for look-up table

I dont see any I-J or K values lol ;P

maybe I should just get out a thermometer a multi-meter and a lighter and give it my best shot

Edited 1 time(s). Last edit at 12/31/2017 09:18PM by JustSumGuy.

DONT use a lighter... approx 1970C , will damage thermistor.

according to this page type 1 is close enough

[reprapworld.com]

Quote
Dust
DONT use a lighter... approx 1970C , will damage thermistor.

I was kidding

dang it after all that work I was really hopeing to use that script

But thanx I will try type 1

I found it!!!!

I don't think type 1 would have been very accurate, would have worked but been out a fair bit much like the type 5 I have been using.

now to work out how to put this info into marlin.....

Can someone plz take a look at this and tell me if I did this right?

I attached an Excel sheet of the info below as formatting doesn't look right on a cut paste from Excel....
The table creator I found was setup to make the table for every 5 deg but the data I had was every 10 deg so I adapted.
Will this be a problem?
Now how to use this......

Do I just cut paste over an existing thermistor table and use the # of that table in my config?

Thanx in advance


Deg C - RT RT/100 Marlin Table


0 354.6 3.546 { 283 , 300 },
10 208.8 2.088 { 326 , 290 },
20 126.9 1.269 { 376 , 280 },
30 79.33 0.7933 { 436 , 270 },
40 50.9 0.509 { 509 , 260 },
50 33.45 0.3345 { 596 , 250 },
60 22.48 0.2248 { 701 , 240 },
70 15.43 0.1543 { 830 , 230 },
80 10.8 0.108 { 987 , 220 },
90 7.69 0.0769 { 1180 , 210 },
100 5.569 0.05569 { 1416 , 200 },
110 4.097 0.04097 { 1708 , 190 },
120 3.058 0.03058 { 2067 , 180 },
130 2.313 0.02313 { 2507 , 170 },
140 1.77 0.0177 { 3045 , 160 },
150 1.371 0.01371 { 3696 , 150 },
160 1.074 0.01074 { 4478 , 140 },
170 0.8501 0.008501 { 5398 , 130 },
180 0.6793 0.006793 { 6452 , 120 },
190 0.5476 0.005476 { 7623 , 110 },
200 0.4452 0.004452 { 8877 , 100 },
210 0.365 0.00365 { 10159 , 90 },
220 0.3016 0.003016 { 11405 , 80 },
230 0.251 0.00251 { 12546 , 70 },
240 0.2104 0.002104 { 13538 , 60 },
250 0.1775 0.001775 { 14351 , 50 },
260 0.1507 0.001507 { 14984 , 40 },
270 0.1287 0.001287 { 15452 , 30 },
280 0.1105 0.001105 { 15783 , 20 },
290 0.09539 0.000954 { 16008 , 10 },
300 0.08278 0.000828 { 16154 , 0 },

Edited 1 time(s). Last edit at 01/02/2018 12:50PM by JustSumGuy.

will the following work? I plan to replace thermistortable_8.h with this and adjust a few other files to reflect the different thermistor name that table 8 will now be.

/**
* Marlin 3D Printer Firmware
* Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
*
* Based on Sprinter and grbl.
* Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [www.gnu.org].
*
*/

// 100k SEMITEC 104NT-4-R025H42G (4.7k pullup)
const short temptable_8[][2] PROGMEM = {
{ 283 , 300 },
{ 326 , 290 },
{ 376 , 280 },
{ 436 , 270 },
{ 509 , 260 },
{ 596 , 250 },
{ 701 , 240 },
{ 830 , 230 },
{ 987 , 220 },
{ 1180 , 210 },
{ 1416 , 200 },
{ 1708 , 190 },
{ 2067 , 180 },
{ 2507 , 170 },
{ 3045 , 160 },
{ 3696 , 150 },
{ 4478 , 140 },
{ 5398 , 130 },
{ 6452 , 120 },
{ 7623 , 110 },
{ 8877 , 100 },
{ 10159 , 90 },
{ 11405 , 80 },
{ 12546 , 70 },
{ 13538 , 60 },
{ 14351 , 50 },
{ 14984 , 40 },
{ 15452 , 30 },
{ 15783 , 20 },
{ 16008 , 10 },
{ 16154 , 0 },
};