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Unidentified pattern and horizontal ribs

 Greetings!

I need some technical advice. A few months ago, wide horizontal ribs started appearing on my prints along with vibration-like patterns on the sides. -See pictures attached-

I've been tinkering with the settings on a basic level (acceleration, for example), even if I'm not entirely familiar with the whole set of G-codes for the Reprap/Marlin system, so I might have screwed something up. Now I'm stuck...


The code was generated in Cura with 20mm/s print speed, 0.15mm layer height and 95% flow rate to make the flaw stick out more.


XY acceleration is 1000mm/sˇ2 , Z is 250mm/sˇ2


Any ideas?


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Hey. 


Are yo talking bout the color variation in the printer, i.e. the horisontal lines, or is it the crappy corner? 


The color variation could be uneven temperature in the hotend, I've had similar problems on a different brand printer. 


the corners, I would say i related to flowrate and/or material. What type of material are you printing with? 

Hi!
I used PLA this time, but the results were the same with ABS.
What you see is not color variation, those are the wide horizontal ribs, or rather bumps I was talking about.  -Probably my desk lamp was a bit too strong.-

 

Ok, then I have to ask if you left the PLA out in the open for a longer time? 


Do you have a alternative material, like a new spool that has been stored in a sealed enclosure to do a comparing test with ? 


I could very well be that what you see is related to moisture in the material, especially PLA will behave similar to this if it is left in the open for some time. 

It was left out in the open, at least in the drawer under the printer. Like I said however, I had the same problem with ABS. Once I get home I'll upload a pic of one of those test objects.

-Any suggestions about how I should remove the moisture? (oven temperature, etc.)

 I have the same problem. Are the width of the horizontal bands the same regardless of the size of the part? It is in my case. That rules out anything that is time related (such as heat varying in the extrruder or bed) since if that were the case the bands would be closer together for parts that take longer to print. Are the width of the bands the same as the threads on the ball screws? My theory is that the root cause is Z-axis wobble. In other words the bed shifts around a little as it moves up and down. In the commercial machines (I've looked inside a Stratasys Fortus when it was being serviced) The bed is on large linear bearings. Of course that's one reason they are so expensive.

 Actually, the notorious Z-axis wobble is what I fear the most... I'll do some further prints to check if these waves are of the same width. 

In the first few months, if my memories are correct, vertical walls were perfectly straight. Is this wobble an unwanted "feature" or is it because of the stress endured while working?

That's a good question. I don't know if it's always been there in my case or not. I've had my printer for over a year. I think some materials make the problem more obvious. I'll have to look at some old parts I did. (I also kept the test print that came on the machine so I will check that too.)

 

Done... different material (ABS instead of PLA), an object twice the size of the previous one. Same 5mm ribs on sides 2 and 4, semingly fitting into each other. That looks like the wobble you mentioned.


-Does anybody know a way to correct this?

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Note: I have the more recent ball bearing/spindle version, so wobble shouldn't be an issue...

 

So do I. (I think they are 20mm diameter).
I am at a loss to explain the symptoms from anything else.
I'm certainly no expert, but it seems that ball screws aren't intended (by design) to be a replacement for a good set of linear bearings.
Add a couple of of good bounces on the delivery truck (the pallet was broken on mine) and there you go.
Perhaps if you loosened everything and then re-tightened it, it would help. Just guessing.

 

Thanks, might try that this weekend!
Still I hope somebody has another possible solution.

 

I looked at the test print that was on the machine when I received it.
It has the horizontal waves in it also. Not quite as noticeable because its a rather rough print but they are there.

 

Just thought of something that can be worth checking. How is the tension of the X/Y/Z axis belts? Also, what about the linear bearings, are they running smooth? 


I just realized that on our old printer, we had similar problems with irregular horizontal lines, in this case the printer had been in action for a while, without any actual maintenance. 


We went over and tensioned the belts, lubed the bearings and calibrated, since then we haven't seen this issue. 


Maybe worth checkin in to ? 

You mean you had such waves? I'll definitely try this then.

 

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