I'm in the process of doing some much needed upgrades to my printer's heatbed, and I'm trying to workout my best option.
The existing heated bed was done with 4 x 4.7R power resistors (aluclad type) and the temperature maxed out around 70C. I have just mounted 4 x 2.2R power resistors, but I haven't tested them yet. They're 8W as opposed to the 15W ones that were there, and although they have a max temp rating of 300C, I'm a little apprehensive about them, and the wire that connects them. It's really thick, but by my calculations, there's going to be something like 21A through the wire, and I'm not sure if it (or my RUMBA board) will take that. The power supply DEFINITELY will, as it's rated for 58A at 12V. Pics of the current bed and wires (I put in a normal single core wire beside it for comparison):
![1192ly1.jpg]( "1192ly1.jpg")
![6qwlqv.jpg]( "6qwlqv.jpg")
Anyway, this all has me considering some other heater solutions, but there's a few issues involved, and I'm trying to do this as cheap as possible really.
So, PCB. I'd be looking at a 300x300mm one, but because of the existing gantry, the corner mounting holes wont work. The one in the middle is fine, but I'd need to drill new holes in a PCB heat bed, and I don't know if i can do that. I have a vague recollection of some site saying it was fine provided it was outside the white outline of the text/border on the top surface of the heatbed. Confirmation of this would be great
The other two options are Polyimide or a silicon heater mat. With the polyimide, same principle of having to drill it applies. The silicone mat, same thing.
I think i'd prefer the PCB option so i can keep the weight down, but I'm a bit stuck on this one. As you can see on the image of the bed, the mounting holes are the problem with the options, but it would be less so if I could drill a PCB heater.
Anyone able to shed some light on the situation?
The existing heated bed was done with 4 x 4.7R power resistors (aluclad type) and the temperature maxed out around 70C. I have just mounted 4 x 2.2R power resistors, but I haven't tested them yet. They're 8W as opposed to the 15W ones that were there, and although they have a max temp rating of 300C, I'm a little apprehensive about them, and the wire that connects them. It's really thick, but by my calculations, there's going to be something like 21A through the wire, and I'm not sure if it (or my RUMBA board) will take that. The power supply DEFINITELY will, as it's rated for 58A at 12V. Pics of the current bed and wires (I put in a normal single core wire beside it for comparison):
Anyway, this all has me considering some other heater solutions, but there's a few issues involved, and I'm trying to do this as cheap as possible really.
So, PCB. I'd be looking at a 300x300mm one, but because of the existing gantry, the corner mounting holes wont work. The one in the middle is fine, but I'd need to drill new holes in a PCB heat bed, and I don't know if i can do that. I have a vague recollection of some site saying it was fine provided it was outside the white outline of the text/border on the top surface of the heatbed. Confirmation of this would be great
The other two options are Polyimide or a silicon heater mat. With the polyimide, same principle of having to drill it applies. The silicone mat, same thing.
I think i'd prefer the PCB option so i can keep the weight down, but I'm a bit stuck on this one. As you can see on the image of the bed, the mounting holes are the problem with the options, but it would be less so if I could drill a PCB heater.
Anyone able to shed some light on the situation?