Good to know I not the only one who has had this problem. I prefer something didn't have to hack the fiirmware, but probably have to do that for a force sensor also. I wonder if I could just put some sort of primitive spring like electrical sensor around the head to catch when the head is diving into something. Edit: thinking about it I could just have the sensor also trigger the z stop I suppoby firefox4001 - Reprappers
Well I sort of down now that I busted my X nozle carrage right after my first part print. It was looking ok but I didn't want to print whole thing, So I try to stop it and then the dam thing wouldn't let me move the Z axis up to get the head out of the way. I got frustrated and hit home and then the thing rammed into the printed part breaking the carrage part. It would be nice if some day they hby firefox4001 - Reprappers