Analyze Thermistor?

fcwilt · 24 Feb 2021, 23:57

Hi,

When confronted with a machine with existing thermistors without specifications is they any way to test them or any device that can test them to determine their characteristics and thus the values need to configure them for RRF 3?

Thanks.

Frederick

droftarts · 25 Feb 2021, 00:10

@fcwilt Measure resistance at 0C (stick between ice cubes), 25C (or room temperature) and 100C (stick in boiling water) then use https://www.thinksrs.com/downloads/programs/therm calc/ntccalibrator/ntccalculator.html

Or just replace them!

Ian

fcwilt · 25 Feb 2021, 02:10

@droftarts said in Analyze Thermistor?:

@fcwilt Measure resistance at 0C (stick between ice cubes), 25C (or room temperature) and 100C (stick in boiling water) then use https://www.thinksrs.com/downloads/programs/therm calc/ntccalibrator/ntccalculator.html

Or just replace them!

Ian

Thanks much.

The one in the extruder looks like a common cartridge type but I won't know for sure until I take the extruder assembly a part which I am putting off for now.

The heated bed is a bit of a mystery - I see no way to access the thermistor - I cannot even locate where in the bed it is. I suppose I could forgo the heater in the bed and stick a Keenovo on the underside. Or order a piece of tool plate cut to size. Putting that off for now too.

Frederick

Veti · 25 Feb 2021, 05:50

@fcwilt said in Analyze Thermistor?:

Hi,
When confronted with a machine with existing thermistors without specifications

my first place to go is look at the marlin config if it exists.

droftarts · 25 Feb 2021, 07:12

@fcwilt what printer is it?

Ian

fcwilt · 25 Feb 2021, 12:43

@Veti said in Analyze Thermistor?:

@fcwilt said in Analyze Thermistor?:
Hi,
When confronted with a machine with existing thermistors without specifications
my first place to go is look at the marlin config if it exists.

That is a good idea - it did come with a SD card that might have that information.

Frederick

Veti · 25 Feb 2021, 12:45

https://github.com/MarlinFirmware/Configurations/tree/import-2.0.x/config/examples

fcwilt · 25 Feb 2021, 12:46

@droftarts said in Analyze Thermistor?:

@fcwilt what printer is it?

Ian

This one:

Link to printer

Frederick

fcwilt · 25 Feb 2021, 12:46

@Veti

Thanks.

Frederick

droftarts · 25 Feb 2021, 12:52

@fcwilt Looks like github repo is here, this is the best line I could find quickly: https://github.com/my3dltd/F1-B-V2-NANO/blob/31874e09f71b465f56eeb7b6ba4938376e794848/robin_nano35_cfg.txt#L168

Ian

Veti · 25 Feb 2021, 12:54

that does make sense. its an ultimaker 2 clone.
ultimaker 2 uses thermocouples. so this clone does too.

fcwilt · 25 Feb 2021, 13:07

Thanks for the help.

I will investigate these resources later today.

Frederick

engikeneer · 25 Feb 2021, 14:30

@fcwilt for a quick & dirty check, you could always stick the bed in your oven, set the temperature to ~80deg and leave the wires dangling out the door. Even better if you have a reliable thermistor/thermocouple setup to put in to get an accurate reading of how hot the oven is. Repeat for a few temps and see how different the generated parameters are?

fcwilt · 25 Feb 2021, 14:39

@Veti said in Analyze Thermistor?:

that does make sense. its an ultimaker 2 clone.
ultimaker 2 uses thermocouples. so this clone does too.

Well I treated them as thermistors in RRF3 and they seem to work.

At least I was able to complete M303 but I used the B value from a thermistor I knew which is not likely to be correct.

Frederick

fcwilt · 25 Feb 2021, 14:41

@engikeneer said in Analyze Thermistor?:

@fcwilt for a quick & dirty check, you could always stick the bed in your oven, set the temperature to ~80deg and leave the wires dangling out the door. Even better if you have a reliable thermistor/thermocouple setup to put in to get an accurate reading of how hot the oven is. Repeat for a few temps and see how different the generated parameters are?

I do have an good meter for measuring temps.

Frederick

droftarts · 25 Feb 2021, 14:53

Is the text config file a new thing in Marlin? It still only seems to set the hot end temp sensor, but it is Thermistor #1, so you should be able to look that up in Marlin. Really they should be posting their full Marlin source, where I guess the bed sensor is hard coded.

Ian

fcwilt · 25 Feb 2021, 15:05

@droftarts said in Analyze Thermistor?:

Really they should be posting their full Marlin source, where I guess the bed sensor is hard coded.

I will see what I can find but the web sites are sometimes a bit confusing.

Frederick

droftarts · 25 Feb 2021, 15:21

@fcwilt can you use the Robin Nano electronics with the STM32 port of RRF? I don’t see it in @gloomyandy ’s wiki. https://teamgloomy.github.io/getting_started.html

Ian

droftarts · 25 Feb 2021, 15:34

Looks like the Robin Nano uses STM32F103VET6, so I guess not.

Ian

gloomyandy · 25 Feb 2021, 15:36

@droftarts said in Analyze Thermistor?:

Robin Nano

Short answer is no, not supported.

Longer answer is that there are different versions 1.x/2.x uses the STM32F1 mcu which we don't support. 3.x has an STM32F4 which we do support. However it uses a different SPI unit for SD card access to all of the other currently supported boards (plus a bunch of other differences). Given that we normally read the SD card to get a config file that describes the hardware this means it won't currently work. There are changes in the (currently unreleased) V3.3 version of the port that may make it possible to support the V3 board, but it is not something we have tested so far.