no accurate temperature reading

[roald 2]

Hello, i have connect the 104NT-4 thermistor to my ultimainboard V2.1.4 and select number 5 : 100kΩ  ATC Semitec 104GT-2/104NT-4-R025H42G in marlin 2.1.

but it still measure a temperature of 8 degrees by a ambient temperature of 19 degrees.

already measure 127kohm so the sensor looks oke. Do the board V2.1.4 support this type of sensor?

[gr5 2,177]

Marlin is expecting a very simple circuit where there is a 4.7k or 47k (depending on which sensor table you use) resistor in series with the temperature probe.  But the Ultimainboard V2.1.4 which goes on the UM2 printer has an op-amp circuit that is much more complicated and designed specifically for PT100 resistors.  I recommend PT100 resistors as they are great.  They are cheap, can be tiny, and come in all kinds of sizes.  And every PT100 resistor table is identical to every other no matter the manufacturer.  Unlike normal thermistors.

 

However it might be possible to create your own resistor table.  Maybe.  I'd look at the circuitry first and figure out what resistance results in what voltage at the "arduino" first and then from there you could use that info plus the thermistor table you have.  You might find that when the temp gets above or below a certain temperature you are at the full scale reading of the ADC so it might not be possible.

[roald 2]

Thank you gr5 for your answer. the thing is i want use the revo heater core on my ultimaker original plus but the don't use pt100 thermistors.

But as i understand you this board and thermistor is not the best combination, maybe better switch to a duet3 mini 5+ wifi board or do you advise me anything else?

 

 

[gr5 2,177]

For an UMO+?  In that case yes a duet would be great.  Even better go with something compatible with Klipper (klipper3d.org) which is where all the innovation has been these last 5 years.

 

Keep in mind the print bed is PT100 sensor also and many 3d printing hardware don't work well with pt100.  If you go for duet then get one of these adapters for the heated bed:

https://docs.duet3d.com/User_manual/Connecting_hardware/Temperature_connecting_PT100

 

Also the bed heater needs 24V.  The servos on UMO will work with 12V or 24V but 24V may give you more torque.  The revo comes I believe in 12V or 24V versions.  Make damn sure you get the 24V version if you are going to use the UMO 24V heated bed (putting 12V into the heated bed gives you 1/4 the power - half the voltage gives you half the power with heaters - which would make it pretty useless).  Duet handles either voltage.  It would be a shame to switch to 12V just because you bought the wrong revo.  duet recommends 24V even though it will work with 12V.

 

But if you are an experienced programmer and not afraid of a bit of math or if you know a little about electric circuits, then you can just change the sensor table, rebuild marlin and use that.

 

 

[gr5 2,177]

Actually I think you can probably power the 12V revo with 24V but just beware that will be 4X the power and that means the power supply that comes with the UMO+ won't be able to run both the nozzle and bed at full power all the time but hopefully in the duet configuration (certainly in Marlin) you can limit the max power to the nozzle heater to be 25%.

[roald 2]

gr5 thanks for your advice. i have the 24v revo hemera xs installed on my umo+ with a um2 heatbed.

i will give klipper a change so i think i need to begin to order a raspberry pi, bigtreetech skr mini control board with a pt 100 attachment for the bed?

[gr5 2,177]

I've read a lot about klipper but have not used it.  And I know it is rapidly growing in popularity.  But I don't know much about the hardware.  I have "heard" that Rspberry pi's went from about $25 each to crazy prices lately.  I know klipper will run on beagle bone black as well but I think Raspberry pi is probably the most common solution along with some kind of stepper controller board.  I think it is immensely easier to go with duet but more fun to go with klipper.  Duet is very easy to setup.  Klipper software is pretty easy but I don't know about setting up hardware for use with klipper.

[gr5 2,177]

Also most klipper users don't have UM2 style bowden feeders where the hot end and cold end are about a half meter apart.  This means a lot of the "advance" settings and jerk and acceleration settings might be so far out from the most common printers that no one will know how to set it up or the software might not even be veryl helpful at calibrating subtle improvements for a UM2 style printer.  I don't know.

 

um2 style printers have super light print heads which can accelrate at about 5 to 9 meters/s/s.  Most printers struggle with 1 m/s/s if they have a moving bed and 3m/s/s if they don't.  This changes a lot!  Also because the um2 bowden tube is so long there is a huge delay/spring effect - when you speed up the feeder, it takes a while for the pressure in the head to restabilize at the new pressure.  When the hot and cold end are both in the print head (more common) this delay is tiny and yet is still compensated for by the "pressure advance" algorithms which are greatly improved in klipper.  But I don't know if they can extend from a typical delay of a 2 inch bowden to a 27 inch bowden.

[roald 2]

Oke good point i go think about with option duet or klipper fits for me.

Underneed my setup i cannot wait to run it.