Heat Bed died in the middle of 17 hr part

[zhangxueyou]

How do you mount the mainboard on Acrylic board?

I know what you mean. I couldn't mount the board so that the MOSFET's are nearer to the blowing fan, doing that will block the access to the USB terminal.
And since the design of the RAMPS board is too tight to mount a heat sink on the MOSFET's, I decisded to make an extension using thick wires, taking the heat bed MOSFET out and mounted a heat sink on it.

This is a good method.