Abnormal Z Axis movement

[palad0n]

Geeetech acrylic I3 Pro B printer. After some experimentation, and wasted filament, finally got my subject printer to do some real stuff - BUT. The but is at approximately 90mm high (Z axis) it longer progresses the required height step. End up with messy print and nozzle definitely within the print layer. It is F'n annoying to be some 3-4 hours into a print to have it screwed by this problem.I have redone the z axis M8 screws as best I can. There is NO Z wobble. Manually raising the bed no longer incurs some very apparent lack - as in no grinding/binding. This happens for about 20mm or so and then it prints as it should. Any suggestions, opinions welcome. I'm really thinking of ditching the M8 and going for T8. Or maybe something with MUCH better tolerances - have you observed how much the M8 stuff 'moves' without been asked to? Is the T8 solution better or a samo samo?

[Toy]

Hi there, I think you can post a picture to show the problem more clearly.

[palad0n]

z move.png (1.25 MiB) Viewed 12146 times

[Toy]

How about trying this, it might help to prevent z axis from the wrong movement.
http://www.thingiverse.com/thing:1424358

[palad0n]

Thanks for that, but it is not z axis wobble. I eliminated that problem - M8 screws are not constrained at the top. It is the z axis not stepping upwards at the required height - the nozzle just pushes the molten material around during its print that layer mode. For some, extremely unknown reason, the problem disappears after another 20mm or so of height. Irrespective, it is a problem that I cannot resolve. There is a basic engineering/design flaw there somewhere that I cannot see and/or infer. Without that I cannot devise a solution. I have now firmly decided that I'll replace the M8 stuff with T8 stuff.

I do note for the record, for GEEETECH, that this is the 2nd major failure of their design. The 1st being the(new improved but seriously design flawed) filament feeder system. I grow weary of spending my money on wasted filament (1 whole roll effectively) and replacement of inferior components. I would greatly appreciate some consideration of recompense here. Screw the time I have spent, it's the actual $'s I have spent.

As for the wasted filament, I'm NOT going to get into redrawing this back to 1.75mm filament. I'm hoping that I can create molds, remelt the useless artifacts and create items this way.

[ggg666]

Thanks for that, but it is not z axis wobble. I eliminated that problem - M8 screws are not constrained at the top. It is the z axis not stepping upwards at the required height - the nozzle just pushes the molten material around during its print that layer mode. For some, extremely unknown reason, the problem disappears after another 20mm or so of height. Irrespective, it is a problem that I cannot resolve. There is a basic engineering/design flaw there somewhere that I cannot see and/or infer. Without that I cannot devise a solution. I have now firmly decided that I'll replace the M8 stuff with T8 stuff.

I do note for the record, for GEEETECH, that this is the 2nd major failure of their design. The 1st being the(new improved but seriously design flawed) filament feeder system. I grow weary of spending my money on wasted filament (1 whole roll effectively) and replacement of inferior components. I would greatly appreciate some consideration of recompense here. Screw the time I have spent, it's the actual $'s I have spent.

As for the wasted filament, I'm NOT going to get into redrawing this back to 1.75mm filament. I'm hoping that I can create molds, remelt the useless artifacts and create items this way.

Hi,
Could you please attach the gcode or stl file of the printed object?And,did you observe how it goes when the "accident" was happening? Maybe some parts like the rods on Z axis moves abnormally...

[palad0n]

Seems the z axis layer height increases work OK, as seen in the pic, until a certain point. Then it seems to be less than that required as the nozzle is printing the layers and is also pushing the molten filament around. Thus the result seen on the pic.

[ggg666]

Seems the z axis layer height increases work OK, as seen in the pic, until a certain point. Then it seems to be less than that required as the nozzle is printing the layers and is also pushing the molten filament around. Thus the result seen on the pic.

So,i wanna know,every object has the same problem?And on the same height?