Electronics is not my specialty so perhaps this is a dumb question but here it goes.
I have a 6" Prusa i3 from MakerFarm which came with their PCB heated bed, apparently using Josef Prusa's MK1 design with MakerFarm silkscreened on the top. It uses resistance heating and a very long trace path which heats up when you pass current through it. The amount of current is regulated by one of the MOSFET parts on the RAMPS board with a heatsink attached. Right?
The problem is this: the bed does not heat evenly. It seems like a simple problem of thermal distribution. I use 1/8" plate glass over the heated bed. The center of the bed (where the thermistor is located) gets at least 15C hotter than the edges, with an even greater difference toward the corners. I'm measuring using a multimeter + thermocouple taped to the glass.
I hear this often: you won't get flat prints from ABS, there will be warping without a heated chamber. Looking at the large variance in surface temperature, I'm wondering if there might be a way to design the board with unevenly spaced traces (of even width).
It's also possible the board I have is poorly manufactured - there are apparently some boards out there constructed from plated rather than clad copper. Or perhaps the MK1 design was meant to use with kapton tape covering rather than glass?
Thoughts?
I have a 6" Prusa i3 from MakerFarm which came with their PCB heated bed, apparently using Josef Prusa's MK1 design with MakerFarm silkscreened on the top. It uses resistance heating and a very long trace path which heats up when you pass current through it. The amount of current is regulated by one of the MOSFET parts on the RAMPS board with a heatsink attached. Right?
The problem is this: the bed does not heat evenly. It seems like a simple problem of thermal distribution. I use 1/8" plate glass over the heated bed. The center of the bed (where the thermistor is located) gets at least 15C hotter than the edges, with an even greater difference toward the corners. I'm measuring using a multimeter + thermocouple taped to the glass.
I hear this often: you won't get flat prints from ABS, there will be warping without a heated chamber. Looking at the large variance in surface temperature, I'm wondering if there might be a way to design the board with unevenly spaced traces (of even width).
It's also possible the board I have is poorly manufactured - there are apparently some boards out there constructed from plated rather than clad copper. Or perhaps the MK1 design was meant to use with kapton tape covering rather than glass?
Thoughts?