ErikZalm/Marlin — Issue #30: Endstop behavior is wrong
Author: cakeller98
Created: 2011-12-08 14:23:18+00:00
State: open

Problem: current position can be past the endstop, but when moving away from the endstop it moves relative to endstop, not the current position.

to illustrate:

>>>M114
SENDING:M114
X:0.00Y:0.00Z:0.00E:0.00 Count X:0.00Y:0.00Z:0.00
>>>G1 X-1000
SENDING:G1 X-1000
echo:endstops hit: X:0.00
>>>M114
SENDING:M114
X:-1000.00Y:0.00Z:0.00E:0.00 Count X:-0.02Y:0.00Z:0.00
>>>G1 X10
SENDING:G1 X10
>>>M114
SENDING:M114
X:10.00Y:0.00Z:0.00E:0.00 Count X:846.70Y:0.00Z:0.00 (but the print head has since crashed into the far end of the X axis, and continued to try and move beyond the end for ~850mm because well... somehow it thought it was actually AT -1000, vs realizing that I'm at the endstop, I'm at ZERO, and won't move until the real position is greater than ZERO! :)

---- however, the move moves 1010 mm from the endstop!!!

this is HORRIBLY bad behavior!

another example - if you have a code that say G1 Z-1... when you go to Z0.4, you end up at Z1.4...

I know it's a known bug, but I don't see it listed in ISSUES.