J-Head element keeps burning out?

Just put together a chinese Prusia i3.
Got it printing, But I have burnt out 3 (J-head) hotend elements in the last 3 weeks, and only printed out 6 test box's.
What have I done wrong?
This can't be normal. Please help.


Info:
Using pronterface
3 different J-head hotends
thermostats seems to work
I think I may have seen it get to 301 before heading back to 250?

Edited 2 time(s). Last edit at 04/22/2015 07:16AM by bob the builder.

Quote
bob the builder
I think I may have seen it get to 301 before heading back to 250?

Way to hot for a true jhead (one that uses peek). About 250 is the maximum operating temperature for the PEEK and it's really recommended to not operate anywhere near this temperature.

Do not exceed 235 on Chinese J heads, at 240 melt start even with a fan.

PLA prints nice at 195 and ABS at 230-235.

Found that the firmware ( sent with the He3d i3 ) had a max temp set at something like 375.
Thanks for the help guys. Much appreciated.

Hello
Could somebody post hear Configuration.h file for this printer He3d i3 please? I would be very grateful.