Please share your B57540G1104 config for RepRap 3.1.1...

Aaron_Nall

As the title suggests I need the config for the EPCOS B57540G1104 thermistor.

I'm using it for my single extruder hotend powered by the Duet 2 WiFi board.

When I use T100000 B4092 R4700, and even with a C value calculated from this calculator with -55c, 25c, and 280c based off of this data sheet, I still get readings that are 60c+ higher than actual temperature at target 250c. (my infrared thermometer only goes to 250c)

What am I doing wrong? Does someone already have this thermistor dialed in to within a few degrees Celsius?

PS - The reason I'm targeting 280c is because I need to print ePA-CF at 60-70mm/s. I topped out at 40mm/s at 250c. Someone told me they hit my target print speed at 280c.

Veti

@Aaron_Nall said in Please share your B57540G1104 config for RepRap 3.1.1...:

EPCOS B57540G1104

if you have a ir thermometer then do your own measurements.

measure resistasnce at 3 temperature
room temperature
100C
280C

then input them in the configurator
https://configtool.reprapfirmware.org/Heaters
click on the Beta and select custom.

that will be better than any table because its specific for your thermistor.

or you could get a pt1000 thermistor. they are far more accurate.

BoA

I would remove "R4700" part.

I have:

M308 S0 P"temp0" Y"thermistor" A"Heatbed" T100000 B4092

BTW - max temperature according to datasheet is 250*C, so it is not reliable at 280*C.

dc42

You cannot measure the temperature of a hot end accurately with an IR thermometer. They need large areas to work with. Chances are that your readings are about right and the IR thermometer is under-reading.

I suggest you use the Custom option in the online configuration tool and enter values from the data sheet for 25C, 280C, and somewhere in between e.g. 150C.

Don't use a C value calculated one way and a B value from somewhere else. The C value affects the B value that you need.

Aaron_Nall

@dc42

I'm pretty sure the IR thermometer is reading accurate within ~5c because it works on the other printer I have within that range.

If the IR is under reading so drastically then why wont the filament melt? Is there another reason that the filament melts in another printer at 250c and not this machine with the EPCOS thermistor?

Thank you for your help.

dc42

Have you tried my suggestion of using the online configurator and 3 temperatures from the table to determine suitable parameters? As I mentioned before, you cannot use a C value calculated one way with a B value calculated a different way.