7x 1.2ohm dummy loads made from nichrome toaster wire and bamboo skewers.
Used on the 5v rail to stabilise ATX 12v output under load and supplement bed heating without overheating the bed. Construction materials include Bamboo skewers. Used Nichrome wire from a broken toaster. Insulated wire from a broken ATX, tie wire, solder(hot) and heatshrink.
Each heating rod consumes around 5w of power and dissipates heat over a large surface are to keep the max temp below 50c. So the Heat beds PWM can still control print temp.
Benefits include:
-Efficiency. Less power used doing something useless, more power used doing useful work.
-Faster bed warm up times and more stable printing temps.
-More stable 12v output under heavy load.
-Slower bed cooldown times. Reduces warping.
-Less fuse tripping due to more stable 12v rail and less power required to raise & maintain bed temp compared to no secondary heater.
Difficulty of replication: Easy
Components
1×
Broken Toaster
Wire from one element should be enough for most printers. So three printers could be hacked from one toaster.
7×
Bamboo skewers
Comonly used as the stick part of "meat on a stick".
14×
Conectors
Heatshrink, Insulated wire, solder etc to make electrical conections
Decide how hot you want the heater to get. This should be 10-20c below the lowest print temp you expect to run the bed at.
2
Step 2
Test your resistor wire (nichrome in my case) with a 5v supply and a temperature probe. You want to find a length that uses as much current as possible without exceeding your lowest printing bed temp after 15 min of being powered (the heater may continue to heat up after 15 min, but hopefully not by much).
3
Step 3
Once you have decided how long your resistor wires need to be. Its time to wind them onto bamboo rods so they can be held in place easily. Be careful to keep some space between turns as you dont want the wire to short to itself. This will reduce resistance, drawing more current and generating more heat. Kapton tape may be helpful here.