Heated Chamber

So when I built the enclosure for my Predator 3d printer, I envisioned at some point adding a chamber heater. I made allowances in the design and construction for adding this additional element. Well, i’m finally moving forward with this project. I have a $10 heat gun, a $15 Solid-State-Relay, and some spare time.

I spoke of my planned chamber heater implementation on a forum for 3d printer enthusiasts, and was quickly warned away from using a heat gun. They are not rated for use this way, and another user had experienced a catastrophic failure doing exactly what I intended to do.

So I dropped some cash on a better solution. I should have all the parts I need by this weekend.

Even without all the parts I’ve so far managed to set up the SSR(Solid State Relay) and the temperature probe for the heated chamber.

Now I just need the heater itself and a fan to move the hot air around. The trick is not to move the air too much. I want mostly calm air around my print, as moving air will cool it too fast. Even the hot air is cooler than the extruded plastic. In an effort to duplicate the successful chamber heater of someone on the duet forums, I’m using a 220V fan being driven by 110V so it runs at half-speed(or therabouts).
Configuring the firmware was not difficult. RepRapFirmware version 3 is very well put together. I only needed to add a few lines:

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M308 S2 P"ctemp" Y"thermistor" F0 T10000 B3950 				; Chamber temp thermistor'
M950 H2 C"exp.pa21" T2 ; Create chamber heater pinout
M141 H2 ; declare chamber heater on Heater2
M143 H2 S60 ; Set chamber max temp 60
M307 H2 B1

Perhaps I should have the chamber heater be heater 3 rather than 2, but its only a single-tool machine. Heater 0 is the bed, and heater 1 is the extruder. So heater 2 is the next one by count.

This is an awful lot of work to go to in order to be able to print ABS without warp. But I do so like the look of acetone-smoothed ABS. And this should help me make better parts which I can then smooth.
PETG is a fine material, and I’m largely migrated to it from ABS, but I have a large stockpile of ABS filament that I want to use up, and the heated chamber will let me do it without warp.