I am running a RepStrap consisting of a hot end with parts from various sources and using Slic3r and Mach3 to print.

   I typically ref my machine at the beginning of a print or during that working seesion (I am not running limits or home switches on this particular configuration just yet). After reffing I use an M8 command to turn on my heater controls. All is working pretty well in those regards, however at the end of my print I use a G28. Not knowing any better this does 2 things, it rewinds the extruder and gets the filament out of the barrel so clogs are less of a problem and eventually ends in an M30 which turns off all outputs. These are great features. especially in printing where a part might take 6 hours or more. Babysitting was not my intent.

   The questions I have are,

  1. Is there a way to have the A axis only retract a specified distance from where the program ended instead of all the way back to 0? This value would always change (at least with each different print).

  2. Is there a way to initiate the M30 before the G28 automatically?

 Also I notice the G28 runs very slow at the end, most likely reading the last feed rate posted? These questions probably belong elsewhere but you know how it is. Thanks