Why does my print have tiny zebra stripes?

[DrR1pper 4]

Awesome job Torgeir!

[gr5 2,170]

I found that lower acceleration reduced quality because then you get the extruder speeding up and slowing down which causes over extrusion when it slows down (corners) and underextrusion in between. Same thing with lower jerk.

However with high values you can get another quality issue that most people call "ringing" and look similar to zebra stripes but is different.

[DrR1pper 4]

Interesting gr5.

May i ask what values you have found to produce the best print quality or does the optimal acceleration and jerk value per printer also depend on other factors?

Thanks

p.s. i went with the 800 mm/s^2 and 10mm/s values for the time being as a test because the wanhao duplicator 6 uses them and i've got a print sample from one which i've been using to compare print quality with.

Edited May 30, 2016 by Guest

[valcrow 144]

I also printed Valcrow's «curve-test-print», to see how this print will be. However, I never printed this before this change, so I have no idea what to expect.

 

Those are nice curves and steps not present

[SandervG 1,521]

Hi Folks,

Just made this last picture of two of my "3D Bechy Boat" print, the boat to the left is printed before I made the configuration change to the main PCB. (It's not a hack, just hardware configuration.) The boat on the right side is made after this change.

It is the same gcode file that is printed as close as possible to the front of the printer, some vibration here when the extruder accelerate/decelerate.

Anyway, as you can see -there is no zebra stripes anymore.

I also printed Valcrow's «curve-test-print», to see how this print will be. However, I never printed this before this change, so I have no idea what to expect.

https://www.youmagine.com/designs/curve-test-print

I made 3 picture of this print, so here they are for you to see.

Thats all.

Thank you.

Torgeir.

 

Thank you for your post, it looks like a huge improvement in a small level of detail!

To achieve this you pulled the ROSC pin to ground? Are there any drawbacks to this?

@DrR1pper, thank you for sharing all those comparisons. I do find it hard to say which of the models looks best. It looks like they both have lines, except (if I recognize the matt from the shiny correctly), it looks like Ultimakers are vertical and Zortrax are diagonal. What do you think?

[cloakfiend 995]

Is there a thread about this configuration change? as it is also nozzle vibration related, hence development of the sacred ruby nozzle.

if the change fixes the weird lines, and the ruby nozzle comes out. then FDM really will be much improved. until that happens any improvements (such as the +nozzle kit) are avoiding these main issues.

....And for any noobs out there i personally would not bother doing ANY mods unless these very problems are addressed. Lets hope UM addresses them first! starting with an ultimate upgrade kit for the UM2 LOL.

I think the 'Ultimate Ultimaker 2 Upgade Kit' has a nice ring to it!

Edited May 30, 2016 by Guest

[DrR1pper 4]

@DrR1pper, thank you for sharing all those comparisons. I do find it hard to say which of the models looks best. It looks like they both have lines, except (if I recognize the matt from the shiny correctly), it looks like Ultimakers are vertical and Zortrax are diagonal. What do you think?

 

No problem. Those diagonally curved lines (that kinda look like very large finger prints lol) that you can see on the zortrax prints i posted are also on the um2+ however if you click on any of the images showing those diagonally curved lines in my post to see the full/higher resolution versions, you will see that they don't actually exist on the prints. It's just some artifact caused by the forum showing a smaller resolution version of the images for some reason.

It's really hard to see in the pictures i provided but when i look at the two again really closely and in the right lighting, there are in fact  the exact sane vertical lines on the zortrax print as well only they are far less visible. Interestingly the distance between each of the repeating vertical lines (i.e. wavelength) on the print surface are also the same. However they are far more visible on the um2+ print. I'm starting to think it is very possible (as you rightly called out on an earlier post of yours, sorry,) that this is purely due to the material being PLA on the um2+ and ultrat (an abs derivative) on the Zortrax since ABS material is matt vs PLA glossy, the matt will conceal any surface print irregularities much more where as glossy will highlight them. I have ordered some 2.85mm black ABS and will try this comparison again as it's not really fair otherwise.

Edited May 30, 2016 by Guest

[Torgeir 242]

Hi SandervG,

Thank you for your post, it looks like a huge improvement in a small level of detail!

To achieve this you pulled the ROSC pin to ground? Are there any drawbacks to this?

Can't see any "main" issue, except for a little more hi frequency sound when micro stepping and (ofc) more current when micro stepping.

Thanks.

Torgeir.

[Torgeir 242]

Hi cloakfiend,

 

Is there a thread about this configuration change? as it is also nozzle vibration related, hence development of the sacred ruby nozzle.

I've not seen anything about configuration change, this is more to designers of such system. But maybe there is something like this in here some places?

When I put the Bechy-boat as far to the outer side as possible, it was just to see/follow the printing close up...

The vibration "issue tread" do exist in here, I've seen this some time ago...

If I want a steady print, I'll place the "object" all the way in, and to the right side.

Thanks.

Torgeir.

Edited May 30, 2016 by Guest

[cloakfiend 995]

lol, i do the same regarding placement, i find the back right side of the bed is best! but the ruby nozzle visibly reduces vibration from macro photos ive seen from neotko, i dont know where he placed his print though.

just was wandering about the 'ROSC pin' thing i guess, as the benchy boat did indeed look cleaner. im always afraid of circuit modding as that is not my field. the lines are still there but aligned differently.

Edited May 30, 2016 by Guest

[neotko 1,417]

lol, i do the same regarding placement, i find the back right side of the bed is best! but the ruby nozzle visibly reduces vibration from macro photos ive seen from neotko, i dont know where he placed his print though.

just was wandering about the 'ROSC pin' thing i guess, as the benchy boat did indeed look cleaner. im always afraid of circuit modding as that is not my field. the lines are still there but aligned differently.

 

So far about the vibrations. The new beta nozzles doesn't do that effect. Weirdly enough the old beta nozzle does. Remains a mistery so far. I print my tests right in the middle.

[DrR1pper 4]

Does print location affect the print surface quality that much? Does is show like a z-wobble artifacts or something?

[gr5 2,170]

@DrR1pper - I looked at photos of that printer and it looks like the feeder is on the head so that's why it has such a slow jerk and acceleration setting. The UM2 can go to 9000 accel I believe and certainlyl 20 jerk no problem.

The reason you tend to get better quality is that with those high accel/jerk the head barely slows down on corners such that you don't get much underextrusion on the long straitaways. With low accel you can hear the head slowing down for every corner and then you get overextrusion (pressure in the nozzle) and then as it speeds up out of the corner you get underextrusion a little bit. The faster you print the worse this is. But if you have very high accel the extruder barely needs to ever slow down and can (almost) constant feedrate and constant nozzle pressure for a consisistent smooth flow of filament onto your print (no over extrusion, no under extrusion).

[DrR1pper 4]

@gr5 - Thank you for that detailed explanation!

Is there a particular 3d model that you would suggest i use to more clearly highlight the impact that different acceleration values have on the print surface quality or will a standard shell of a cube suffice?

Lastly, do you think there could be less of an impact of underextrusion on the long straightaways if the printer uses a direct drive extruder and/or 1.75mm filament?

@Torgeir - Would the wonderful modification you have found/implemented to remove zebra stripes on your UM2 also work on any and all 3d printers that suffer from this issue?

[Cohen 4]

I have read the nophead article a long time ago, but I never knew the print results were this good. We have not found the time to properly test this yet, I hope we can do this in the foreseeable future, so we can implement this.

[DrR1pper 4]

I have read the nophead article a long time ago, but I never knew the print results were this good. We have not found the time to properly test this yet, I hope we can do this in the foreseeable future, so we can implement this.

+1

Please do, then the print surface quality will be as good as the zortrax (i.e. no zebra stripes).

[chrii 5]

 

Hi SandervG,

Thank you for your post, it looks like a huge improvement in a small level of detail!

To achieve this you pulled the ROSC pin to ground? Are there any drawbacks to this?

Can't see any "main" issue, except for a little more hi frequency sound when micro stepping and (ofc) more current when micro stepping.

Thanks.

Torgeir.

 

 

Just my Expierience with the so called Decay Hack (ROSC pin to ground), that is alreaday known to the A4988 drivers since some time.

I did the hack for over a year on my other printers, with success on all steppers /printers i have.

I also discussed that issue also with valcrow since long time.

so i finally tried the decay-hack on the UM board 2.1.1 , with bad results.

(i`m skilled at soldering so no problem from this side )

first i did the hack on X and Y axis on the board, resulting that the X driver instantly burned after powering it up, Y axis is still okay.

after that i reconfigured E1 to be the new X axis, and printing was well with that "decay" lines also dissapearing on the Y axis, so its definitly the cause of the effect.

Here a picture of the comparison, before and after:

Ignore that X, its Y axis ^^

Unfortunatlye i then did the hack on the E1 driver, resulting in also a burned driver after powering up.

Normally setting ROSC to ground should not be an issue there, but maybe some UM engineers ma have a look on it why steppers altough tend to burn up when do the hack.

So far, now i have a bricked UM2 standing here :(

Chri

[Torgeir 242]

lol, i do the same regarding placement, i find the back right side of the bed is best! but the ruby nozzle visibly reduces vibration from macro photos ive seen from neotko, i dont know where he placed his print though.

just was wandering about the 'ROSC pin' thing i guess, as the benchy boat did indeed look cleaner. im always afraid of circuit modding as that is not my field. the lines are still there but aligned differently.

Ok, I see...

Maybe we could start a new tread about vibration, ringing etc.

Have no idea about this nozzle?

Torgeir

[Torgeir 242]

@gr5 - Thank you for that detailed explanation!

Is there a particular 3d model that you would suggest i use to more clearly highlight the impact that different acceleration values have on the print surface quality or will a standard shell of a cube suffice?

Lastly, do you think there could be less of an impact of underextrusion on the long straightaways if the printer uses a direct drive extruder and/or 1.75mm filament?

@Torgeir - Would the wonderful modification you have found/implemented to remove zebra stripes on your UM2 also work on any and all 3d printers that suffer from this issue?

Hi DrR1pper,

I'll think such a reconfiguration of the driver can improve all printers "with this problem" having installed this (A498X) series of stepper drivers from the manufacturer “Allegro micro system”.

Thanks

Torgeir.

[Torgeir 242]

I have read the nophead article a long time ago, but I never knew the print results were this good. We have not found the time to properly test this yet, I hope we can do this in the foreseeable future, so we can implement this.

Hi Cohen,

It was actually MartijnvG in your team that goggled the link to nophead's article.

Posted Jun 23, 2015 - 4:25 PM

hmm i did some searching, and it seems the issue is indeed in the fact that the 1th or last step in the microstepping seems to be un-event to the rest of the steps.

i found an old thread about it. http://hydraraptor.blogspot.nl/...12/04/stepstuck.html we are using the A4988 chip i think so maybe this solution might be a nice way to fix it.

Thanks

Torgeir.

[Torgeir 242]

Hi SandervG,

Thank you for your post, it looks like a huge improvement in a small level of detail!

To achieve this you pulled the ROSC pin to ground? Are there any drawbacks to this?

Can't see any "main" issue, except for a little more hi frequency sound when micro stepping and (ofc) more current when micro stepping.

Thanks.

Torgeir.

Just my Expierience with the so called Decay Hack (ROSC pin to ground), that is alreaday known to the A4988 drivers since some time.

I did the hack for over a year on my other printers, with success on all steppers /printers i have.

I also discussed that issue also with valcrow since long time.

so i finally tried the decay-hack on the UM board 2.1.1 , with bad results.

(i`m skilled at soldering so no problem from this side )

first i did the hack on X and Y axis on the board, resulting that the X driver instantly burned after powering it up, Y axis is still okay.

after that i reconfigured E1 to be the new X axis, and printing was well with that "decay" lines also dissapearing on the Y axis, so its definitly the cause of the effect.

Here a picture of the comparison, before and after:

Ignore that X, its Y axis ^^

Unfortunatlye i then did the hack on the E1 driver, resulting in also a burned driver after powering up.

Normally setting ROSC to ground should not be an issue there, but maybe some UM engineers ma have a look on it why steppers altough tend to burn up when do the hack.

So far, now i have a bricked UM2 standing here :(

Chri

Hi Chri,

Sorry to hear that.

I've got the same version V2.1.1. as you have. I studied the data sheet and the original drawing "from github" for some time before this modification, just to make sure there was no issues...

However, I made all drivers at once as I would like to have same configuration to all drivers.

The current during micro stepping at 100% should be like 500 mA max. each coil., so no problem.

Anyway, glad you solved it.

Thanks.

Torgeir.

[chrii 5]

Hy Torgeir, do you have a picture of your board wiring ?

To which ground point did you go ?

my problem is not solved , the two drivers are dead, so its not able to print anymore.

Chri

Edited June 1, 2016 by Guest

[cloakfiend 995]

Can any of this de-stepping be achieved via some sort of firmware update or something or is soldering stuff the only option, the prints look waay cleaner. If someone could post a step by step guide, or point me to one, i would love to give it a try.

Edited June 1, 2016 by Guest

[SandervG 1,521]

I forwarded this towards my colleague in R&D (so you know we are aware), and personally I am also curious to the complexity of this fix. The improvement is bigger then I would expect it to be.

[chrii 5]

Hy SandervG

I hope they will find a solution, the hack itself is easy in "therory", just replace a SMD resistor under every stepper to a solder bridge, so no big deal.

But unless they haven`t checked it through and gave a feedback, i don`t publish a public guide, just too dangerous atm ^^"

chri