Updating QU-BD hotend with 12V 40W heater cartridge

Way back, a long long time ago, I bought a QU-BD extruder thinking 40 bucks would be worth it. Well after about 3 weeks of printing the damn thing kept failing. Upgrade the drive gear, printed some thingiverse stuff and all was fine again, until this week when the resistor would not take me to 180C which I needed for PLA.

So I decided to replace the Resistor with a 40W 12V ceramic cartridge that I purchased from MiniInTheBox.com. So after drilling out the resistor and expanding the hole to accommodate the new cartridge it was time to fire it up.

So first off let me warn you that when you turn this thing on for the first it, it will SMOKE and smell like crap. But this did not deter me. After the smoke died down it was time to get it to 180C and low and behold it jumped to 180C then past it to 195C, then back down to 165C, then back up to 195C…  It was giving me a sinus.  Right so next was PID autotune:

M303 S180

The value that was given back was uploaded in the firmware, and time to test it again…  Hmmm not good still a very very big Sinus and no stability what so ever.  So I jumped online and found a site that pointed to me to the correct start settings:

#define  DEFAULT_Kp 45.0
#define  DEFAULT_Ki 4.2
#define  DEFAULT_Kd 120
Again upload and testing, now the sinus was still there but it was smaller. Then I realized something very important.  I had drilled out the Brass block and therefore removed a lot of the material normally needed for heat, and with that had failed to re-insulate the head!  I wiped out a roll of Kanton tape and insulated the head with a lot of tape. Results…  It now kept a nice 180C with a drift of 1C top and bottom.
Next is M303 again to see if I can get it even more stable…
MOTTO OF THE STORY: Even-though most people on the Internet say that you should not have to insulate your head, not doing so is really not going to get your head temp stable.

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