Adding extra limit switch

When the extruder is cold and I hit print there is sometimes a little bit of plastic off the extruder that prevents the Z axis from homing properly. This causes the nuts that hold up the Z axis to leave their homes. When it finally starts printing it tears up my tape and I have to redo the Z axis.

I was wondering if I could modify the software/firmware to allow for an extra limit switch that I can put under one of the nuts, so if it gets hit it will send a fault warning to my PC and have it abort the print.

If it cant be done then I can just tie the switch into the arduino reset pins. It will be the lesser preferred option, but it will keep me from having to fix the printer.

Another thing that would help is if I could tell slic3r to heat the head before sending the printer to home. (On this line I guess I could add a line that would tell the printer to heat the extruder to ~180 no matter what the final temp needs to be.)

 

If you go to the manually move printer tab then at the bottom there is a button to manually heat the nozzle , thats all i do and when its warm usextweezers to remove any excess and run the job

 

How about getting the print head to heat up, thereby softening the plastic, before it goes home and then starts printing... Not sure of the g codes however

 

Deadwood, That is what I am currently doing, but I sometimes forget. Plus that is something that should just be automated. (I am a test engineer, and I try to remove as many steps as possible from processes that need to be done many times.)

 

Casey, is your Z axis stop oriented correctly? Many printers went out where the switch was reversed causing people to throw their nuts. If it looks like this then it's reversed and you should turn the switch around so that the Z limit screw doesn't hit near the fulcrum of the switch.

 

I fixed that a couple of days ago. The cold plastic on the extruder is causing me to throw the nuts as it is making the Z axis just shy of hitting the switch. I guess I could also just add the offset back into slic3r. That worked out pretty well for me before I knew my switch was backwards.

 

It is not a blob, its just a little piece that is cold.