Chamber cooling fan setup and gcode integration
I need to print a lot of PLA in my VC4, and I also need to have the printer enclosed and with the front panel attached for noise and cat reasons. My rear panel has custom cutouts at the top and bottom to allow air to be moved around. I have extra 3950 thermistors, one lower in the chamber and one at bed level.
As a basic controlled cooling system, I would like to use a PWM fan to draw air in at the bottom of the chamber, which would be passively exhausted through openings at the top. The bed will typically be at 60C. I would like the chamber temperature to be maintained at a reasonably constant level regardless of external ambient air temperature, which can vary seasonally between 12C and 25C. I don't want to over-cool the chamber. I expect the ideal set point would be in the 25-30C range. I don't want to use bang-bang control for noise and temperature consistency reasons.
In a pure klipper setup, I would expect to:
* Use a
[temperature_fan] section to define the fan (https://www.klipper3d.org/Config_Reference.html#temperature_fan)
* Use [temperature_fan] PID to provide smooth fan operation and temp control.
* Use a custom gcode macro to allow gcode to set the target temp (eg, as mentioned here https://docs.vorondesign.com/community/howto/alchemyEngine/chamber_temperature_exhaust_fan.html)
My questions are:
* Are there any relevant hooks or integrations in RatOS that I should consider?
* If a print does not complete, so that the end gcode which disables chamber cooling is not executed, how do I ensure that the chamber cooling is turned off?
* How should I tune PID, notably given that the ambient external air temp can vary? Might I need an additional ambient external air temp thermistor? If so, how could this be integrated in the PID control?
* I am a klipper newb, suggestions and guidance are welcome.14 Replies
Are there any relevant hooks or integrations in RatOS that I should consider?in this case, no RatOS is just klipper and you can do anything that klipper allows. I print PLA a lot, and it needs lots of cooling (never have I hit the point of too much cooling). So I personally would simplify the operation and have fans exhausting the chamber all the time.
Thanks for the insight. My concern with the fixed/manual approach is that I need to control surface gloss quite accurately for aesthetic reasons, sometimes using speed variation to achieve a gloss transition effect. In winter the ambient temp can vary quite widely throughout the day due to only heating the building for certain hours. Generally the fewer variables I have to consider, the better, hence my thinking that a consistent chamber temp would be preferable.
Previously I was using other printers in a room with pretty consistent ambient temperature, and with no enclosure, so I don't actually know how much is an issue ambient temp variation will be.
just create a temperature fan, have a look in the klipper documentation
this lets you control a fan by temperature, automatically
no need to change nay macros
yeah, that's my plan. as per original post - one question - if I turn the fan on via gcode generated by the slicer, how to I ensure the fan gets turned off if the print is cancelled or does not complete? Is there some "cleanup" hook to extend?
no, once configued the fan would be running
this is unrelated to ratos
ok, I'll look at klipper docs.
@tg73 Sorry to dig up an older thread. Would you mind posting pictures of your pack panel vents? I am debating doing something similar as keeping the front door on greatly reduces noise but has an effect on PLA prints. Active chamber ventiliaton seems like a nice solution.
remind me tomorrow (~12hrs from now). I'm just signing off now, would need to hunt for images etc.
Sounds good will do! Thanks!
Little more than 12 hours thanks to time zones ha. Also curious if you have this up and running and how well the cooling works? I’m hesitant to cut holes in my panels for the fans!
I haven't designed the actual thing yet. I just had the holes cut. I did rough out the volumes for what I had in mind.
The plan is: green - wide area inlet with a large merging duct behind leading to a 6039 fan. Diverter flap after fan to send a portion of the air to outside (either lots of air for PLA or maybe a trickle for eg ABS to maintain negative pressure in the enclosure). Then 50/60mm hose down to the bottom. Use the lower holes on one side or the other (I hadn't decided, will blank the ones I don't use). Red would be the air outlet with a vaned duct that shoots the air out fanning out across the base plate. Blue would be a weighted gravity flapper valve that allows air to be drawn in when a lot of air is being sent away via the diverter flap. Might need both blue's. The flap would be hinged at the top edge and open into the enclosure, but with a bit of weight so it only opens when needed.
see above (forgot to reply)
Appreciate this! Thanks for sharing!