Michael correct me if I'm wrong, but I think the answer is it never stops short on a direct G1 Yxxx command, only on a G28 home command. In terms of the GCode Jin suggested, what is being described is this behavior:jsc wrote:What I am interested in is if it ever stops short when you are not using the Home Y button, just when it is commanded to do a long y axis travel move.
1. On the home command the bed stops short and marlin thinks it is at y=0, though the end stop is not tripped.
2. When he then puts in G1 Y250, it goes to 250 but overshoots, and has to be stopped by emergency cutoff to save the steppers. Makes sense given 1.
3. On the G1 Y0 command the bed moves all the way to endstop. (That could be odd but given the disconnect in step 2 maybe not.)
So it seems to depend on the home command getting to marlin, where something funny happens during the execution. My plan is to have a look at the code for homing and see if I can get a sense of what might be going on, but anyone interested and more familiar with the marlin source, go for it.