Heated Chamber Scanning Z Probe

Bad-Joker

Hello everyone in the Duet3D forum

I have a question. I would like to use the scanning Z probe in my 3D printer that will have a heated chamber. But the main board of the z probe can only be used up to 80 degrees. Is it possible to solder cables directly to the sample pcb and extend the cable outside the chamber because the 305mm cables you get are too short in my case? Or would cooling with a fan also work? Thank you in advance.

dc42

@Bad-Joker I don't think long cables would work well, in any case if the cables are moving and flexing as the head moves then the capacitance between the cable and ground will change, ands this will vary the sensor oscillation frequency and therefore affect the height reading.

A fan will only work if you pipe cool air to it from outside the chamber.

An alternative might be to put insulation around the board and use a Peltier device to keep it cool. The Peltier device would need to provide sufficient temperature difference between its hot and cold surfaces to keep the board cool enough, and tolerate the hot surface being at the chamber temperature.

Bad-Joker

@dc42 Hello dc42 Thank you for the quick reply and all the information. I'll see how I can implement your tip with the Peltier device. I really want to use the sensor. Since I have never used a Peltier device, do you think an aluminum heatsink is enough for the Peltier device or should I also use a fan? Or is the fan of no use at these temperatures? I am very grateful for your help.

Maestro

@Bad-Joker Whether a pelt can do what you need it to do without a fan is not a simple question that someone can confidently give you a yes/no answer on.

If you are allowing your sensor to hit 80C and your chamber to be 110C, your first thought might be that you need a peltier that creates a 30C difference. That is not the case; you need a pelt that will sustain a higher temperature difference, because if the hotside of the pelt/heatsink is at 110C, it is not releasing any heat to the chamber. I.e., your hotside must be higher than chamber temperature. Additionally, the pelt itself is a heater to the extent of it's inefficiency, which will also vary with temperature and temperature difference. The balance will be determined by the °C/W rating of your heatsink, which varies heatsink-to-heatsink, as well as with airflow. So, you are chasing a multivariate equilibrium point, and the answer is therefore "maybe, maybe not."

Another option would be to put the sensor on a waterblock and watercool it, in which case the answer to whether it is cool enough will almost definitely be "yes."

Bad-Joker

@Maestro Hello Maestro

Thank you for your help and the information. In the meantime I have already collected some information regarding the Peltier device. And then I saw, as you wrote, that it won't be that easy in terms of the heat that needs to be dissipated.

And I've already looked at the idea of the water heatsink and that will be the better solution.

Thank you everyone for everything. I'll have to see how I can do the rest myself. Thanks

oliof

@Bad-Joker consider there is a deadline above the coil where you shouldn't have any metal; you may need to add ferrite sheet to keep the coil functional.

Bad-Joker

@oliof Hello Oliof

Thank you for the information, I didn't know about the ferrite sheet. Thank you. When drawing the holder, I made sure that the coil had enough upward clearance from all metal parts. Thank you

Bad-Joker

@dc42 I still have one question, should I cool the board from the component side or from the back side? Which side would have the better cooling effect?

dc42

@Bad-Joker for the SZP board it probably makes very little difference which side you cool it from. I suggest you cool it from the back and put thermal insulation over the front.