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How to enter a user defined thermistor table?

Posted: Sat Jul 04, 2015 12:11 pm
by Fabio
I've been dialling in the Max v2 gradually over the last week with the E3D hot end and starting to get there.. However I've found the thermistor they supply to a bit wacky - I've had to set the temps for PLA right up to get good prints even though I have defined table 8 in the Config.h file as per E3D's recommendations.

After seeing a few posts I decided to upgrade the thermistor for a M3 stud type - I ordered two and they arrived from the US in GB this morning. They are a EPCOS 100K Thermistor (B57560G1104F)

Now I've looked up the table on the reprap wiki and it's listed as this:

// EPCOS 100K Thermistor (B57560G1104F)
// Made with createTemperatureLookup.py (http://svn.reprap.org/trunk/reprap/firm ... eLookup.py)
// ./createTemperatureLookup.py --r0=100000 --t0=25 --r1=0 --r2=4700 --beta=4092 --max-adc=1023
// r0: 100000
// t0: 25
// r1: 0
// r2: 4700
// beta: 4092
// max adc: 1023
#define NUMTEMPS 20
short temptable[NUMTEMPS][2] = {
{1, 821},
{54, 252},
{107, 207},
{160, 182},
{213, 165},
{266, 152},
{319, 141},
{372, 131},
{425, 123},
{478, 115},
{531, 107},
{584, 100},
{637, 93},
{690, 86},
{743, 78},
{796, 70},
{849, 60},
{902, 49},
{955, 34},
{1008, 3}
};



what is puzzling me at the moment is exactly how to enter this into the Config.h file correctly..

If I changed this:

#define USER_THERMISTORTABLE0 {}

to this:

#define USER_THERMISTORTABLE0 {\
{1,821},{54,252},{107,207},{160,182},{213,165},{266,152},{319,141},{372,131},{425,123},{478,115},\
{531,107},{584,100},{637,93},{690,86},{743,78},{796,70},{849,60},{902,49},{955,34},{1008,3} }


and then

change this line:

#define NUM_TEMPS_USERTHERMISTOR0 28

to this:

#define NUM_TEMPS_USERTHERMISTOR0 20

use table 5 would this then be correct? Would that be all i need to do?

Thanks in advance! :)

Re: How to enter a user defined thermistor table?

Posted: Sun Jul 05, 2015 7:40 am
by Fabio
Anyone?

I need to know whether the values need the 4 and 8 multipliers added or not? I do not know at present how to check if the table is a sprinter one which needs those multipliers according to the documentation..

I'm guessing that they do?

cheers

Re: How to enter a user defined thermistor table?

Posted: Sun Jul 05, 2015 7:56 am
by teoman
The values do not look like they need multipliers. (From what i see).

Do you have athermocouple that you could experiment and verify?

Re: How to enter a user defined thermistor table?

Posted: Mon Jul 06, 2015 2:48 pm
by Fabio
I've got a meter thermocouple combo on the way to manually test things - in the meantime my research has thrown up that existing table 1 might be a good place to start as it's 'supposed' to be for generic epcos 100k therm's so I'll try that and see before I go entering the table manual for a user defined one :)

Re: How to enter a user defined thermistor table?

Posted: Mon Jul 06, 2015 5:40 pm
by teoman
I think that setting is the one i use for the screw in thermistor i got off ebay.

Re: How to enter a user defined thermistor table?

Posted: Tue Jul 07, 2015 3:07 pm
by Fabio
overhauled the E3D today and fitted the M3 therm - I used table 1 and the difference in printing is now literally like night and day!

It sort of confirms my suspicions that the stock e3d therm' was way under-report actual temps at the nozzle by a large margin.

very happy chappy right here and I'm gonna get a few of these therm's as spares :)