Heat bed heater help?
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I have a cartesian style printer with a heat bed size of 320 x 225.I have a .250 MIC6 plate on the way and I am planning on ordering a silicone heater for the printer from Keenovo.I have a few questions regarding the heater.I was planning on ordering a 12v version with an Auber or similar relay to use with my Wifi.I have a Meanwell power supply that has open 12v terminals so it can directly feed the heater and then the wifi can control it through the relay but I am unsure how long that would take to heat and whether or not I should try ordering and wiring up a 110v version to the mains.I plan on ordering the heater with a semitec thermistor and two openings in the center to allow me to install a replacement thermistor in the future if need be.The second opening would be for a thermal fuse location.The 12v version would be simpler and safer for me I believe although I am capable of wiring a 110v version.I would just prefer to stay away from ac if possible.I will use whichever one will help me get this printer functioning the way it was meant to be.Thanks
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The time it would take to heat up is only dependent on the wattage of the heater, not the voltage. If you can get the same watt heater, you'll be fine with 12v, given the power supply can power the heater and the printer.
So what you need to do is decide what is an acceptable time for the heating up.
Then you need to determine if your existing power supply has the spare capacity to also power the bed.
Determine if the current at the chosen wattage is low enough to use with the Duet2Wifi's bed mosfet. -
The heater can be purchased in either 300 or 400w versions and my PSU is a Meanwell 450 so I am guessing it will be stressed a bit but should be able to handle the load.
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You might get away with 300w, another 40w for the hotend presumably, leaving 110w for steppes.
300w over 320x225mm would give you 0.42W/cm^2 which should be acceptable, and could get you up to temp in something like 7-10 minutes depending on insulation, ambient temperature, airflow etc, maybe less, unlikely to be more.
But 300w at 12v is 25A, and the Duet2Wifi is only rated for 18A heated bed, so you'll need external control anyways, unless you move to a 24V supply if you really want to stay with DC supply. That would benefit the motor drivers, but cause some issues with hotend and fans.
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Thanks for the link the time it will take is a bit longer than what I am currently experiencing but it isn't too bad 10-12 minutes.The weird thing is the calculator only shows a 4 minute difference between the 300 and 600 w versions of the heater.The 600w is only available in the 110v or 220v versions.The 12v version looks like a better option for me with this printer,I will look into the 110v version and 24v PSU on my Corexy plans.
