Temp calibration help

[bernards]

Hi all, I need some help here.

I finished swapping my Max v2 with the Duet board. Things appear to work fine except the prints look terrible and my kid could break apart printed parts with his hands.

I checked the hotend and bed thermistors against a thermocouple and ended up with these figures.

Hotend (Prometheus V2)

Thermistor Thermocouple
190 - 159
200 - 167
210 - 175
220 - 183
230 - 191
240 - 196
250 - 205
260 - 214
270 - 221
280 - 228

Bed (Original Onyx)

Thermistor Thermocouple
50 - 44
60 - 51
70 - 58
80 - 65
90 - 73
100 - 80
110 - 87
120 - 93

How do I translate this data into the config.g for an accurate out of machine reading?

M305 P0 T100000 B3950 R4700 H30 L0 ; Default, left untouched
M305 P1 T100000 B4267 R4267 H30 L0 ; R number taken from Prometheus install

[bob64]

I posted something about this here: http://forum.seemecnc.com/viewtopic.php?f=111&t=10099

Don't change the R number. That's based on the resistor on the duet.

[bernards]

Many thanks. Works great now.

[Great_Thark]

Does anyone know the actual maths behind this. Specifically H & L effect and what points they act on.

I cannot find this info anywhere

[mhackney]

Yes, they are published on the reprapwiki gcode page, the reprapwiki forum and David Crocker, the gent who implemented it, posted some details on his blog. The best way to calibrate a Duet is described on the forum and I have a link to it on my blog here: http://sublimelayers.blogspot.com/2016/ ... files.html

Scroll down to the comments, that's where I put the links.

[Great_Thark]

Thanks, I still can't find exactly what I'm looking for, but i think Ive more or less figured it out.
Could do with a table instead of 25 resistance and beta, as the beta changes quite considerably across the range. Or, if not a table specify r at a selectable point say 190 and then work out beta across the range you're interested in and enter that, as generally accuracy below your working temps is irrelevent on the hot end. Default would be r 100000 t 25.
Personally im going to put a thermocouple in and forget about it. ☺