Definitely having z-banding issues on my eustathios v2.

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(Ben Delarre) #1

Definitely having z-banding issues on my eustathios v2.

I spent some time last weekend dialling in the extruder settings which I thought were causing overextrusion and the banding seen, I’ve now dialled the extruder in just about perfectly (see the test shape in the later photos). But the z-banding remains, its too regular and matches the leadscrew pitch perfectly, so I don’t think I can put it down to extrusion.

Anyone else having banding issues on the v2? I’m wondering if the pair of bearings at the bottom is over constraining the screw? I don’t really want to have to resort to z isolators but I’m not sure how to go about fixing this. Any suggestions?

(Miguel Sánchez) #2

some ideas http://www.soliforum.com/topic/1165/firmware-z-wobble-compensation/

(Ben Delarre) #3

Interesting discussion. I’m on smoothieware though so I’m not sure I can apply that hack easily. Also I think I’d rather solve this mechanically if I can since I’ve seen other people with the v2 having great results so its probably just something I’ve setup badly :slight_smile:

(Ben Delarre) #4

Just as an additional note, the photos of the calibration object make it look like there’s no banding present, there is, but it is substantially reduced. Making me wonder if its an infill issue perhaps, or would the infill just help exaggerate any wobble in the z axis?

(Miguel Sánchez) #5

my first thought is that one of your threaded rods could be bent slightly and it is pushing the bed. a second possible cause would be not xy motion but uneven z-height on each layer (can’t tell for sure from pictures), The latter would be cause by a layer height which is not represented by a full step.

(Ben Delarre) #6

Tested the rods on my table top recently (which admittedly is probably not perfectly flat, but is as flat as I can find right now). Both rods are perfectly straight as far as I can tell. I’m also using the 0.1920 layer height to get full steps, so we can rule that one out too. Thanks for the suggestions though!

(Miguel Sánchez) #7

Lastly it could be the heated bed temperature swinging significantly

(Ben Delarre) #8

No heated bed either, this is on an acrylic bed with a mirror tile on top for flatness. So no temperature fluctuations there, could be hot end fluctuations I suppose but the regularity of it and its periodicity matching the z-screw perfectly points to the mechanical I think.

(Miguel Sánchez) #9

@Ben_Delarre yep, if period matches rods’ pitch I bet that is the source of the problem even if visually it is not noticeable (if you have a dial indicator it may help you looking for side motion on the bed due to the z-axis motion)

(Ben Delarre) #10

Yeah I’m going to have to rig up something to get the dial indicator to run along the edge of the bed this weekend and check it to confirm. Just don’t know what to do about it. The smooth rods are straight and the leadscrews are straight. The leadscrews are in the bearings at the bottom block, and unconstrained at the top. As I understand the mechanics of z wobble if you don’t over constrain the leadscrew you shouldn’t be transferring much horizontal force into the bed but this is clearly doing that.

Could it be that the bottom bearing blocks are not holding the z axis on one side straight causing this wobble, even though I have smooth travel up and down the whole axis? I honestly don’t know where to start in fixing this.

(Miguel Sánchez) #11

Imperfect motor shaft alignment could definitely cause the problem.

(Ben Delarre) #12

The z-axis is driven by belts on the eustathios v2, so its not that, this is what confuses me about it. The design is pretty sound in terms of avoiding all the normal pitfalls.

(Miguel Sánchez) #13

Sorry, I was assuming you had dual motors on Z.

(Jason Smith) #14

Funny you should ask about this. Eustathios #00001 has had the same issue since day 1. I haven’t spent much time investigating, but definitely interested in a solution.

(Miguel Sánchez) #15

Ball screws may be the solution :slight_smile:

(Ben Delarre) #16

@Jason_Smith is #00001 a v2 style with the dual bearings at the bottom? @Miguel_Sanchez no worries, thanks for trying to debug this with me.

(Eric Lien) #17

@Ben_Delarre this is why I think I will change the BOM to use ballscrews instead of leadscrews. I fight it every once and a while, but nothing like that.

(Ben Delarre) #18

@Eclsnowman ah ok, well if you get it too I don’t feel so bad. Your level of patience and attention to detail is well beyond mine :slight_smile:

(Eric Lien) #19

Ballscrews from golmart on aliexpress are cheaper too.

(Ben Delarre) #20

@Eclsnowman I vaguely remember somebody already having made a ballscrew eustathios mod, was it this one by walter? http://www.thingiverse.com/thing:854325

I might bite the bullet and give it a go.