Two Printers With The Same Issue - Bad Surfaces

[wirlybird]

I have a Guider II and a QIDI X-Plus that have developed the same issue. If you hold or feel the extruder stepper you can feel a pulsing or a tap-tap-tap coming from it. IT still does this with the bare stepper, nothing on it. Move the stepper to my Creator Pro and it runs fine.

This is causing a pattern in all surfaces.
If you watch the extrusion you can see little bulges at regular intervals.

I have tried several spools of filament, even brand new, different slicers, hot, cool, slow, fast.
I have run the same filament on other printers and it is fine.
I am at a loss as to what is causing these patterns.

[keebie81]

I have got surface issues like that if I have two printers running on same table. I keep all my lulzbots on their own shelf unit or table because of it.