Duet 2 Wifi Overkill Active Cooling

mihaitintea

Hello

I' ve seen educated advices here from the Creators of the Duet 2 Wifi about blowing a fan to the back of the board.

May I ask please what would happen if I mount the board horizontally between two 120 mm fans, one of the fans blowing towards the back of the board and the other fan blowing towards the front of the board, thus the heated air being evacuated laterally.

Thanks and regards
Mihai

dc42

You will get a dead zone with little cooling, approximately in line with the centre of the fans.

c310

why do you need that? what is the real reason?
40-50 mm side fan will do the job, but if the duet board is not under the headbed, you do not need the fan at all...

zapta

A related question, how can I tell if the DWF has sufficient cooling or needs more? Are there 'reasonable' temperatures for the critical components?

(I do have access to an IR camera.)

JRDM

I use 2.4A on four different motors without issue using this plate and a small blower fan. I think even this plate might be overkill but at least it's easier to access the board as needed.

https://www.thingiverse.com/thing:3504211

A fan over the top side has a major disadvantage of restricting access to the board in case of needing to adjust any connector or cables.

zapta

@jrdm, very nice design. Did you measure temperatures before and after?

JRDM

@zapta Sorry, no I haven't. I did do a few tests to make sure the air flowed consistently but no thermal tests.

DocTrucker

The drivers have active thermal protection. If you are running high current and the steppers stop or miss steps unexpectedly add more cooling.

The passive cooling is good though.

zapta

@doctrucker said in Duet 2 Wifi Overkill Active Cooling:

The drivers have active thermal protection

They also have advanced warning when the silicon reaches ~100C (actual shutdown is about 50C higher at the silicon). I am not sure what the Duet's firmware does with this warning but it is discussed in M305 https://duet3d.dozuki.com/Wiki/Gcode#Section_M305_Set_temperature_sensor_parameters

JRDM

@zapta said in Duet 2 Wifi Overkill Active Cooling:

@doctrucker said in Duet 2 Wifi Overkill Active Cooling:

The drivers have active thermal protection

They also have advanced warning when the silicon reaches ~100C (actual shutdown is about 50C higher at the silicon). I am not sure what the Duet's firmware does with this warning but it is discussed in M305 https://duet3d.dozuki.com/Wiki/Gcode#Section_M305_Set_temperature_sensor_parameters

I didn't set that up because it didn't seem like a good way to go.

On his force cancelling printer, Ian Deckingman used spare thermistor channels to read a thermistor potted to a representative driver chip and some motors to watch their temperatures.

DocTrucker

@jrdm That is on the motors, not the stepper drivers. With lower current stepper motors you can overheat the motors long before the stepper drvivers are struggling.

deckingman

@doctrucker said in Duet 2 Wifi Overkill Active Cooling:

@jrdm That is on the motors, not the stepper drivers. With lower current stepper motors you can overheat the motors long before the stepper drvivers are struggling.

Wes,
I put a thermistor on one of the driver chips too. That's what I use to control the fan that blows air onto the back of the board. These are set thermostatically to start at 40 Deg C.

DocTrucker

@deckingman I stand corrected!