heated bed drops the heat in middle of print

I Have made good prints with PLA annd wanted to go over to ABS.

Started with heat the ext. And bed but the bed went to 92c and then started to drop, it didnt reach 100c.

Tried to manually set temp to different temperatures and then set 100c but it didnt work.

Restarted everything, pulled the cord. Tried again, same problem. Retried 10 times at least, once the temp dropped 1/3 into the print.

What could be wrong?

 

Emil to summarize the issue, the ramps board we believe is using a polyswitch rated to 11A. The heater should only be pulling 9A, but as the polyswitch heats up it's rating drops below 8A.

One solution that's being investigated is using a polyswitch rated to 14A so that even when it heats up, it will still have a high enough amp rating to drive the heater.

One fix, like mark suggested, is to add a fan to the ramps board. Keeping the polyswitch cool keeps it's amp rating above the needed amps for the heater and it won't trip shut.

 

Could someone if they have time post some pics were they placed fans for the bed heating issue on the robo 3d? I did look on the forums for some i may have missed them.
Thanks

 

riley, contact Robo3dhelp@gmail.com. They posted that if you're having the bed cutout, they'll send you a fan that you can connect to the ramps board to fix this problem

 

I did order one of those solid state relays from amazon you had posted in your threads.

 

Awesome. Does anybody else notice 70% of the time spent on the Robo3D is spent fixing this thing or "making it right?"