Hi all. Been printing a few days on my 8200 now. Getting some awesome results considering how new it is to me! Loving every print. There is one weird issue with my prints at the moment which I can think of loads of causes for but just wondered if anyone has had similar experiences. I seem to be getting some weird ridges along the sides of my prints. These occur at regular intervals. I was thinking it might be play along the x and y axis belts? Any wisdom appreciated.
What your print shows is called Z-Wobble.
It is caused by uneven movement of the z axis.
It results in some layers to be slightly lower than others and causes the filament to bulge out sideways.
Most times it is caused by a threaded rod that isn’t completely straight.
A flexible coupling between motor and threaded rod can also help.
Here is my solution that fixed it completely :
K8204 Z Axis upgrade from velleman (Actually any 1.5 to 2mm pich leadscrew with corresponding nut might do)
and hanging down the Z axis from the top.
I recently finished upgrading to a 2nd leadscrew on the right side of the z axis.
I will post the results here and on thigiverse soon.
cheers,
Christian
Ahh nice idea
I assume there is greater tilt at the motor end of the rod hence the inversion?
I shall try the flexible coupler first as mine was the solid metal one and straightness was not one of its main attributes… Looking back on the print of my owl, there was some intermitted smearing of the material at the edge of the print, probably exacerbated by the fact I had quite a dense fill.
When you inverted the setup did you rewire or did you tell the software that the axes were inverted?
Thanks for the advice!
[quote=“5upercrab”]Ahh nice idea
I assume there is greater tilt at the motor end of the rod hence the inversion?
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I don’t get you here. What do you mean by more tilt?
The motor, coupler and leadscrew are perfectly aligned in the hanging mount.
[quote]When you inverted the setup did you rewire or did you tell the software that the axes were inverted?
[/quote][/quote]
I just inverted the z-axis direction in the firmware. Quite easy.
Basically just wondering why you put the motor upside down? Why does that produce less tilt?
I put the motor to the top to rlelease it from the axial load the Z-axis/ectruder assembly applies.
Now the weight is carried by only the flex coupler, so the motor bearings aren’t stressed too much.
It also “straightens” the leadscrew out, keeping it from vibrating to much at the free end.
Hi All
Thought I would post an update on this.
Just switched from the solid Z-axis coupling that came with the printer to the flexible one.
I also re-attached various bits along the Z axis.
Basically I moved the printer arm to the top and tied it to the top of the frame, then loosened off the top bracket. I then detached the motor from its own bracket and let it hang free to find a position where the Z-axis rod is straight through gravity. When it was hanging freely, there was a slight misalignment between the motor and the holes on its mounting bracket. To improve this I packed out the bracket where the Z-axis rod bolts to the main printer arm
(They are pretty hard to see but there is a gap there)!
I then tightened things up again. The Z axis moves sooo much more smoothly now. There is very little wobble in the motor bracket.
I ran a before and after test on a simple cuboid. The result is a big improvement!
These ain’t perfect, the new one still has a little X and Y instability but the key thing is there are no periodic errors like before.
Set the top bearing so the flexible coupling is being stretched slightly. If the weight of the Z-axis is compressing the coupling then it’s all sitting on a spring!