Heated bed print plate questions

[rampeh]

I've finally got my Rostock mostly complete and have started the calibration process and have a few questions about the heated bed print plate (polycarbonate plate included with kit).

1. Am I supposed to cover it with Kapton tape before printing anything to protect the surface from fusing to printed parts?

2. Even when I have plenty of bullclips holding the plate down to the PCB Heater, the board is uneven and unless i apply pressure from near the wiring connections where I can't apply a clip. I can't tell whether this is my PCB not being flat or whether it is the fault of the polycarbonate. Is there a better way to ensure it lies flat?

Thanks in advance,

Anton.

[wonderemporium]

I had quite a bit of trouble with this and ended up getting a piece of 3/8" glass (1/4" should work as well) and putting it over the heater pcb. I held this down with some custom acrylic clips and then put blue painter's tape on the glass to print on. After each print I peel up the tape with the print on it. I wipe down the tape with denatured alcohol first to get the waxy coating off. I get much better adhesion that way. Apparently other people have made the plastic build plates work but I couldn't seem to manage it. The glass also stays stable and doesn't hump or move with the temperature changes, the pcb and plastic will always move at least a little.

Since I changed to this system, I have had over a dozen prints in a row with no problems and no re-calibrations.

[barnett]

I have painters tape on 1/8 inch plate glass on the onyx bed. I dissolve my leftover ABS bits in acetone to a liquid/paste type consistency. Wipe a thin film of that on the tape for guaranteed stickyness.