What would cause this?

Hi all,
I've just finished my second M90 and am having some print quality issues. I printed a herringbone gear and two teeth together have turned out all mushy?
I first printed it using Cura and then using Pronterface/Slic3r and the latter was better but still the issue was apparent. I've attached a pic. In the pic, the gear on the left was printed with Cura and the one on the right with Slic3r. You can see on the Cura printed one that the middle left tooth and the one to its left are all mushy. All the other teeth are ok, on the Slic3r printed one the problem is less apparent but is still there (same positions)

Any idea what might cause this?
Cheers
D

I once had the same issue with printing gears and a lower print speed fixed the problem for me.

I had been playing around with Cura and Slic3r and noticed that the print results especially in corners are much better with Slic3r so I would advice you to stick to that software.



The left is sliced with Cura and the right with Slic3r. You can clearly see that the first one shows really ugly lobes at the corners which is almost not apparent at the right object.

Thank you for that Cocoknight,
I agree that Slic3r does a better job, it's just that Cura is so good at other things, like being able to position, resize, mirror and duplicate stuff. On my other M90 the difference between the two is not as much for some reason and I can live with the offset.
What puzzles me is why the issue (with both slicers) only affects 2 teeth, the other 9 are absolutley fine?
I'll have a go at printing at a lower speed. I wonder if the issue has anything to do with the start and end positions of each layer?
Cheers
D


Edited 1 time(s). Last edit at 01/03/2015 05:14AM by maddog7.

It looks to me that you are over-extruding and I have found that Cura tends to exhibit that. You might also be extruding at an excessively high temperature but that is a bit of a guess on my part.

I would suggest checking your extruder calibration at the appropriate printing temperature. A few more details on what material and conditions are present would help with further diagnosis.

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

I was just watching the machine print and the issues seem to happen at the back of the part as viewed from the front of the printer. When looking at the process it appears like there is a growth of material here. I tried to take a pic of it. As far as I could see all the Z movements were near the front. Come to think of it I printed the hollow calibration pyramid and it had some lumpyness which was always at the back of the part....

D

Edited 1 time(s). Last edit at 01/03/2015 06:19AM by maddog7.

Thanks for that Neil.
I am printing at 200c.
Overextruding seems to ake sense considering the uprising nature of the ridges. I calibrated the extruder to the best of my ability and am as sure as I can be that its extruding the right amount. I will however check the calibration again now. What would be the best way to test the overextruding theory? Could I just try reducing the filament flow a little to test the theory?
Cheers
D


Oh, sorry, material is Faberdashery bright red PLA, currently the printer is non enclosed and sat on my man cave desk at a balmy 23 degrees.

Edited 1 time(s). Last edit at 01/03/2015 06:51AM by maddog7.

Just checked the extruder and over 100mm its about 0.20mm over extruding. When I first calibrated it, it was 3.5mm over. Would such a small deviation cause such an issue?
D

I would adjust the E_STEPS_PER_MM factor to account for that 0.2mm.

You say you are printing at 200C. Is this for PLA? I generally print PLA at 185C using speeds of 40-50mm/s and only go to 200C for speeds of 80mm/s.

Also, again for PLA, are you switching on the fan after the first layer. Active cooling is required for good quality PLA prints.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Quote
neildarlow
I would adjust the E_STEPS_PER_MM factor to account for that 0.2mm.

You say you are printing at 200C. Is this for PLA? I generally print PLA at 185C using speeds of 40-50mm/s and only go to 200C for speeds of 80mm/s.

Also, again for PLA, are you switching on the fan after the first layer. Active cooling is required for good quality PLA prints.

Regards,
Neil Darlow

Hi Neil,
Thanks again.
Will adjust it in the FW but can't help thinking it might not make much difference. I Just tried printing the part again at 95% flow (I presume a 5% reduction as opposed to .2% if that's how the multiplier works?) 40mm/s, 200c, .3mm layer height and the improvement is dramatic. I am using fan on after first layer.

Printed again at the exact same settings but 90% flow and there is improvement again, to the point where if this was what it looked like when I first printed it, I probably would not have noticed. Just gonna print it again at 185c (everything else the same) and see what effect that has.

If my E steps per mm are bang on as calibrated but a significant reduction in flow brings about close to ideal results should I be looking for something somewhere else that's not set correctly?

Will report back on the 185c print in 5.....

Cheers
D

Attached pic has gear on the left printed at 185c and the right at 205c all else equal.

Still not sure the flow rate is quite what it should be but I'm miles better off as a result of the help I've had here.
I'm very grateful.

D

Adjusting the flow rate by 5 or 10% does not seem right. Are your nozzle size and filament diameter entered correctly in your slicing program?

If you follow the Mendel90 calibration procedures correctly there should be no need of adjustments like these. Have you tried printing an object sliced with Skeinforge? I rely on Skeinforge to produce good results where other slicers cannot.

Regards,
Neil Darlow

---

I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Quote
neildarlow
Adjusting the flow rate by 5 or 10% does not seem right. Are your nozzle size and filament diameter entered correctly in your slicing program?

If you follow the Mendel90 calibration procedures correctly there should be no need of adjustments like these. Have you tried printing an object sliced with Skeinforge? I rely on Skeinforge to produce good results where other slicers cannot.

Regards,
Neil Darlow

I agree, 5/10% seems like a lot does it not? I've tried using the laptop I usually use on my other M90 which is the same original J head .4mm as the new one with the same results as my desktop. I'll re-read the calibration procedure again to see if there is anything I've missed.

I'll have a go with Skeinforge, I must admit to having only dabbled a little with it before. I find it quite bemusing.

I did try printing the hollow calibration pyramid at the 205c setting and it did not really fare that well.

Many thanks again for the suggestions......
D

Did you figure out what caused the 10% discrepancy?