prints show wave pattern or wobblyness...caused by...?

Hello guys,

I'm callibrating and closely getting there. I have 3 pictures showing a certain phenomenon, which is a clear manifestation of a wave pattern, accross the layers. What do you think causes this? The first picture is the 0.5mm thin wall object that is widely used. It is for now still 0.7mm but even then I do not see why lowering e-steps would also remove the wave-pattern you can clearly see...

Your insight would be greatly appreciated!



The second one is an gear I printed yesterday. You can see on the edges it is very "wobbly".

I had a similar issue I deleted the photos from my dropbox account a while back, some of the photos are in the form natively.

[forums.reprap.org]

Post details about your setup. What hot end, controller, extrusion steps, extruder, slicer settings ( mainly extrusion multiplier and filament diameter ). Also, go read over [reprap.org]

A lot of people were telling me in the thread that it could be a slicer error/issue. It was not, mechanical. In my case the combination of un-tuned extruster steps, current to the stepper and an all-metal hotend ( e3d v5 ). The v5 was very sensitive to this and I ended up fine tuning the current and the steps/mm very carefully ( using repetier host, tuned things live during the print including the pots on the stepper ). I have since ditched direct drive and also ditched the ramps board in favor of a smoothie board ( azteeg x5 ) because, among other things, I get digital control of the pots.

Hi Bilsch,

I have: classic Mendel with adrian's geared extruder (and hotend), GEN6 electronics, Marlin software (25-02-2012 which I still use because of the 'old' gen6 electronics I am on), pronterface and slicer, a 0.5 nozzle and 3mm filament with layer height set at 0.1969 (best value according to joseph prusa's calculation page instead of 0.2mm). My extrusion width is set to 0.5 in slicer software, my extrusion multiplier equals 1.

From you explanation I will try to first obtain an exact 0.5 width on my 0.5 wall to see of that still gives me the problem.

greetings,,

Hello guys,

I have tried different E-values and tightend the X-belt but the wobblyness is still there...any ideas?

Hmmm, other than maybe tinkering with the current to the stepper, sounds like you have done the debugging I would do.

Can you check to see if you are getting consistent traction on the filament? Is it grinding? How is the temperature on the hot end - are there lots of fluctuations? What happens if you crank it up or down ( crank as in like 2-10C of spec )

I found that if I was not putting enough pressure on the filament I would get failed prints. The failures were usually different in nature - with grip issues I noticed lack of extrusion ( eg, gaps or partially missing layers )

Well I do notice my temperature fluctuates between 182 and 188°C instead of a super-steady 185. That's caused by my rather old GEN6 electronics and I already put in a capacitor to reduce this fluctuation.
So this 3° tolerance could explain the slight wave pattern showing in the X or Y direction, but in my opinion it would not explain the wave pattern in the Z-direction because temperature fluctuates at a higher frequency than the Z-wave pattern. You can clearly see that the must profound wave-pattern manifests itself in the Z-direction.

I'll try to print a set at 190° or 180° to see what happens, maybe the PLA responds differently that way.

Edited 1 time(s). Last edit at 11/28/2014 12:35PM by homecore.

Hello everyone,

After a good chat on the IRC-channels, 2 possible diagnosis were made: too much temperature fluctuation and a Z-axis that was not straight.

I have replaced one of the 2 Z-axis and this confirms the diagnosis: the wave pattern was caused by Z-wobble, meaning the Z-axis was far from straight and the curve in the Z-axis had it's effect on the cross-layer wave pattern. My new axis still is not straight and that shows in the printed objects, but results are better now.

I have no news yet to bring on using PID-control to try to reduce the temperature fluctuations. I'm not sure if it will work well on my gen6 electronics.

greetings,

Edited 1 time(s). Last edit at 12/13/2014 11:53AM by homecore.