What would be a reasonable wattage for a heat bed. I have a 350 W silacone and it is to much W. One that would run on a single power supply but yet heat at least the same speed as a hot end. I am thinking 200W ish.
The problem is amperage. Amperage is what costs money, not voltage. I have a 540W silicone heat bed and my rig just purrs along with it without breaking a sweat. Because it’s 110v, and not 12v.
You may consider moving over to a 24v system.
Running it on mains certainly would make the power supply a reasonable size. A 6A brick would be enough for the Bot.
Don’t make your platform heater too powerful. I tested a heater board with over-spec copper thickness (not enough resistance = too much heater power), and the accelerated heating of the board when the heater kicked on was enough to cause the board to flex due to thermal expansion and make the layer height uneven.
What wattage is your heatbed. if you know. I looked for the wattage of the ubiquitous red heatbed but can’t be found.
When ordering a silicone heater they ask you what wattage you would like, so not knowing what " stock " is it is kind of a stab in the dark.
Don’t have it next to me, but IIRC it’s 1.1 or 1.2 ohms, which would be 120-130W for an 8x8" platform.
So with that information i would like to think 200W should be a NICE wattage. More that stock but hopefully not so much that a single ATX 12V power can’t handle it and the Bot.
@Whosa_whatsis regular PCBs can flex a whole lot as well - i almost went crazy trying to figure out why the bottom layer was always peeling off on my very first prints. Turns out the short time the bed was off after the first layer to drop 10C made it flex about 0.2mm.
A PCB I used on another printer used about 12.5A when cold and to 10.5A when hot (with a perfectly regulated 12.0V supply). It didn’t flinch when I turned up the voltage up to 20V.
@ThantiK most of our electronics are rated up to about 30V, the common Mosfets go up to 50-ish. Going with mains also brings the need for an SSR and the obvious dangers associated with dealing with mains power. So yeah, a 24V supply would make a lot of sense as long as you swap out the hotend’s heater, since it doesn’t add any cost elsewhere.