Frequent Heater Faults on High Temp Chamber (500c)

[GoremanX]

I have chamber heaters that can go up to 500c. I have them mapped as chamber heaters using the M141 command. According to the documentation, M141 must come before M143 (which is used to set the max temperature for a heater). However the default max temperature for a chamber heater is something significantly less than 500c. I assume it's 125c, same as for bed heaters.

In any case, when my heaters are above that default (either because they're still cooling down from a print or the print is paused) and I restart the board, I get an instant heater fault on reboot because M141 sets the heater as a chamber heater before M143 sets its max temperature in config.g. This is becoming very frustrating.

Has this order dependency been eliminated in a forthcoming version of RRF?

[whosrdaddy]

Wow 500c chamber!
Can you show some pictures of your setup?

[dc42]

I have made a note to look at this for the 3.3 or 3.4 firmware release Meanwhile, a workaround may be as follows:

• In config.g, first define the chamber heater sensor number as a different sensor in the M308 command, e.g. the MCU temperature sensor
• Then define the chamber heater using M950, M307, M141 and M143 as usual
• Then redefine the chamber heater sensor as the real one

[GoremanX]

@whosrdaddy The chamber doesn't get to 500c, just the heaters do. They're ceramic IR emitters with built in thermocouples. They heat whatever they're pointed at without doing much to heat the ambient air. Plus the enclosure is enormous and has a filter that recirculates the air from top to bottom, so things don't get THAT toasty in there. Basically, as long as the emitters are on and hot enough, then the object being printed can't dissipate its heat through the air, it can only do so through the build surface. So its internal temperature tends to stay the same as the bed's temperature. Meanwhile the electronics inside the enclosure aren't getting fried. It's been working great for nylon, ABS, PETG, etc with zero warpage, even with very large prints (the bed is 24" diameter).

[whosrdaddy]

Ah I see.
I am in the process building a chamber myself, hence the question (though a bit more modest with 2x 400W PTC heaters)
a few questions:

• Do you blow hot air over the print area?
• Do you provide cold air cooling on the nozzle?

[GoremanX]

@whosrdaddy No, no air blown directly over the print area. The air from the BOFA filter gets blown in through a 90 degree elbow so it gets circulated around the periphery of the enclosure below the heated bed, starting directly under one of the IR emitters.

And no cold air to the heatsink. Ambient air temp rarely gets much higher than about 70c anyways when printing ABS, typically it's more like 40c. This is plenty adequate for cooling the heatsink of the Mosquito Magnum using the stock 25mm fan. I've considered switching to a water cooled Mosquito, but haven't seen a need to yet.

I do however have an external air pump for part cooling, for when I need to do bridging and such. It blows through a tube into a Berd air ring

.