Odd Random Z Banding on Prints

I got this prusa i3 kit awhile back and ended up changing the extruder to e3d after having serious inconsistencies with the cheap Chinese j head that came with the kit.

Now that I got the extruder actually working, I'm having this really odd and inconsistent layer banding issue. The extruder steps have already been calibrated and The z-axis has a nice even 400 steps per millimeter. The printer even has trapizodial leadscrews with flex couplings so I just cannot figure out what's going on here.

Are you using PID on your heatbed? If so, it may need to be tuned. As the PID loop fluctuates the heatbed warps up and down. The only real solution I have found is to use a 4 to 5mm aluminum plate, either with a PCB heater of silicone mat. If PID doesn't help, check for loose axis.

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Master Tinkerer

Actually, PID is the way to go. Bang-bang will cause the sort of problems you're talking about. Of course, the PID autotune function should be run and the firmware updated with the P, I, and D values it returns.

If the lead screws aren't centered on the motor shafts and the frame is flexible, you can get that sort of Z banding problem.

Edited 1 time(s). Last edit at 01/28/2016 05:34PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks for the reply's,

I have not done a PID tune on my bed yet... just my extruder. It would make sense that the bed could be warping considering my setup though.

I know that the leadscrews are centered, but the frame itself I'm not so sure of.

I will check this out tonight

Try a print without the heatbed and see if that changes the characteristics of the banding.

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Master Tinkerer

The bands don't seem to be consistent across all the islands, which makes it less likely to be a bed or lead screw problem. Perhaps a loose head in the carriage, or excessive play in the x and y axes?

So I attempted to re-tightening my entire machine, then I printed this test cube and shut off the heat-bed half way through.
The z-axis artifacts lessened quite significantly, but they are still present in the print. They are still quite prominent...

So the bed was a factor.... I will spend some on the bed to perfect a PID tune.

What else can I do to lessen the Zartifacts?

Edited 2 time(s). Last edit at 01/29/2016 01:18AM by Relativitypro.

No point in doing more than a generic PID tuning command for now, because the noise present without the heatbed is still too much to even see if the heatbed makes a considerable difference. What you should try and do is check for any possible cause of slop, motion, or looseness.

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Master Tinkerer