NEWBEE question

[jack separovic]

Octopus 1.1 .

i would like to  : use the unused themistor to do a chamber /electronics temp monitor and activate multiple  fans based on temp set ,rather than all the time.

i.e min temp  65c 

am runing "CAN"  so the extruder themistor on the board is not used ,or is it .or is there a better way .

same with chamber temp where is that physicly plugged into on board .

and can any one point me into how that is written in printer.cfg or as a macro .or you tube 

 

 

[TitusADuxass]

I have a thermistor peeking through a hole in the rear panel, it reports the temperature at the top of the enclosure and is plugged in to the mainboard (M8P).

You could use the vacant hotend slot.

I can give you the config when I get home this afternoon.

[kharrisma]

Since heat rises, and therefore the top of a heated enclosure will be somewhat hotter than the bottom, wouldn't a better thermistor location be somewhere in the middle?   I'll be dealing with this same issue when it's time to build my enclosure as well, so it's something I'd be interested in knowing.  My impression is that sampling the chamber temperature at the level of the print head would be optimal... or I could go overboard and sample top, middle, and bottom and use the average as the temperature figure.  No criticism, just speculation!

[TitusADuxass]

Just now, kharrisma said:

Since heat rises, and therefore the top of a heated enclosure will be somewhat hotter than the bottom, wouldn't a better thermistor location be somewhere in the middle?   

The middle would probably give you a more accurate reading, but how much difference would there be. I had a CPAP fan that moved the air around quite a bit. The part cooling fan might also provide enough air movement.

Here's my v2.4 temperature readings

Here is what I have for my BTT Pi2 and my BTT CB1 (just change the text to suit).

[temperature_sensor BTT_Pi2]
sensor_type: temperature_host
min_temp: 10
max_temp: 100

For the Chamber temp

[temperature_sensor chamber]
sensor_type: Generic 3950 change this to suit
sensor_pin: PC5 change this to suit
min_temp: 0
max_temp: 100
gcode_id: C

[Jerazmus]

I just added a thermistor in the middle height wise that is ran directly from the octopus. 
Works great for me and you don’t have to wonder if the Extruder or hotend is affecting actual temp readings.  I printed a little extrusion mount for the thermistor type I have and it snaps right in place.  You can move it around to find the best placement easily as well.

 

[temperature_sensor chamber]
sensor_type: NTC 100K beta 3950 your thermistor 
sensor_pin: your pin location
min_temp: 10
max_temp: 100
gcode_id: C

 

Edited August 14, 2025 by Jerazmus

[TitusADuxass]

This is the section of printer.cfg with the sensors and fans.

 

[temperature_sensor CB2]
sensor_type: temperature_host

[temperature_sensor M8P]
sensor_type: temperature_mcu
sensor_mcu: mcu

[temperature_fan CB2_fan]
#[temperature_fan SoC_fan]
pin: PF9
#pin: RPI: gpio26
kick_start_time: 0.8
off_below: 0.8
max_power: 1.0
sensor_type: temperature_host
control: pid
min_temp: 0
max_temp: 100
pid_kp: 1.0
pid_ki: 0.5
pid_kd: 2.0
min_speed: 0.0
max_speed: 0.8
target_temp: 65

[temperature_sensor chamber]
sensor_type: Generic 3950
sensor_pin: PC5
min_temp: 0
max_temp: 100
gcode_id: C

The CB2_fan is not a duplicate, it turns the CB2 cooling fan on and off (I think).

 

[claudermilk]

I also have a standalone thermistor mounted midway up the rear z motor extrusion on my Trident. It plugs directly into a spare port on the Octopus.

[TitusADuxass]

I also had a bed edge thermistor but seems to have disappeared.

The v24 heats up quite slowly and the edges can be significantly cooler than the centre.

So I drilled and tapped a shallow M3 hole and screwed in a thermistor.

[jseparovic]

12 hours ago, TitusADuxass said:

I have a thermistor peeking through a hole in the rear panel, it reports the temperature at the top of the enclosure and is plugged in to the mainboard (M8P).

You could use the vacant hotend slot.

I can give you the config when I get home this afternoon.

Yes please ,and what sort of thermistor are you using ?

[TitusADuxass]

6 hours ago, jseparovic said:

Yes please ,and what sort of thermistor are you using ?

I use these - 

https://www.amazon.de/Hailege-Thermistors-Printers-Temperature-Accessories/dp/B07Z3D51B8/ref=sr_1_5?__mk_de_DE=ÅMÅŽÕÑ&crid=2S00A8ILAKUK9&dib=eyJ2IjoiMSJ9.vEwZ812i4nDna665QAWnS0oBq9JNna4X-6UvFN3DA4uay5Syt5K_RfuGPPFEQaTk8Y6c2r6NU_3F_tmZTrdCNPySCaEcc5fBG2HztL4u2VhmWR61bU4EaK6WiR8x_FHqzBJayit5NIsukbP86087GpkUg87fWknZGRvT85xPuQnrqhLRXCawgkURollK3pj5y2QZdpngD4fRtZG4M_kbOdy7SqQ9cB95WopfkHtppsYSbSZZPunBhnd0jEKZMxNsdLAAkldUVqBJhAdMGsFHoqDn3rMATxk9mRbyRzYsqWs.vsYfALVecoUYd1AvHAcTCREXZHhMbNNEVYG6k7M_8Jc&dib_tag=se&keywords=3d+thermistor&qid=1755237311&sprefix=3d+thermisto%2Caps%2C353&sr=8-5

with this in the config

 

[temperature_sensor chamber]

sensor_type: Generic 3950

sensor_pin: add your pin

min_temp: 0

max_temp: 100

gcode_id: C

 

[Jerazmus]

If you’re not going to put your thermistor into a hole of some sort to protect it you may not want to use the glass bead type, you may want one with a sleeve built onto the end. Sort of like the one in this link. 
 

https://a.co/d/gc7zGK0

Edited August 15, 2025 by Jerazmus

[Penatr8tor]

7 hours ago, TitusADuxass said:

I use these - 

Yup, I have a bunch of those handy as well. They're cheap and they work and they're super valuable for diagnostics, setup rig, etc.

[Penatr8tor]

On 8/14/2025 at 3:58 AM, jack separovic said:

am runing "CAN"  so the extruder themistor on the board is not used ,or is it .or is there a better way .

As far as I'm aware, there is no setup, CAN or wired, where the hotend thermistor isn't used. I assume that you mean you have a spare port on your CAN board. I don't know which CAN board you have but the Mellow 2040 V2 has a built in chamber thermistor right on the board. 

[jack separovic]

Hi no i ment on the octopus board ,as hot end is using the SB2290 can tool board thermistor port .

[TitusADuxass]

6 minutes ago, jack separovic said:

Hi no i ment on the octopus board ,as hot end is using the SB2290 can tool board thermistor port .

Any one of these that's free will do the job.

[jack separovic]

awesome thankyou .