Bug when pausing/resume v2.1.0 win7 64bit

[AndersE]

(Velleman K8200 with e3d hotend)

I sometimes wants to pause a print to change filament, but the following has happened a couple of times now:

When unpausing the extrudermotor goes whacko, and either extrudes or retracts a silly amount of filament. Maybe in the 10cm range or so. So either i get a
LARGE blob on the print which ruins it, or i get NO filament for a couple of layers. Also when retraction happens it seems to loose 1 or 2 layers, which means it
gives a gap in layers.

This happens in 1 out of 5 pauses perhaps. So it is a gamble to pause.

[JoeJ]

Are you literally just clicking Pause, then Resume? Or are you clicking Pause, then doing other things like extruding, changing filament, etc.

[AndersE]

Well i did write "change filament" so... Yes it is when i have paused, clicked on raise z, and disable motors. Unless i disable motors i can't turn extruder gear.
Then when unpausing, it returns to the original position and then sometimes goes whacko.

[Garyhlucas]

On a stepper system of any kind depowering the motors means you are almost guaranteed to lose position, especially if microstepping. There is no encoder feedback for location so the processor only knows where it told the motor to go. If the motor isn't actually in that exact spot then you are screwed.

[AndersE]

I agree when moving x y or z manually. but the extrudermotor does not need to know where it is. So it's stupid to have a paus function then? Never be able to change filament..?

If moving z then i do it with the buttons, the software should remember how many steps i moved, then move back. That function always work (the layer error might be me), but the extruder motor really goes
whack at full speed. It should not extrude or retract at all when resuming.

It happend yesterday again, with a mega big blob of filament on the print.