Poor surface alignment

All,

As everyone knows 3d printing can be frustrating at times and rewarding at other times. I suddenly starting having poor surface layer alignment without changing anything with my machine. Some things I have tried to resolve the issue:
-over hauled my XY axis to ensure there was no binding. With the belts removed, I can move each axis with very little effort (I am using high quality NSK linear bearings)
-removed the lower bearing block from my Z ball screw which appears to be very straight with no wobble present
-over hauled my extruder and hot end setup (installed new nozzle)
-measured my filament in different places and it did not vary more than .03mm
-tightened my belts very tight and also tried losing them some but neither effected the problem.
-increased my XY jerk setting from 20 to 10 and to 40. My accel is set to 3000
-lowered the current on my XY driver in case it was overheating and dropping steps

I tried a different slicer and different models to print but saw the issue with both slicers. I don't know what else it could be, my printer used to have perfect layers alignment but now doesn't. I have a custom built XY core setup, anything else to try?

Just throwing out a few things as I don't know your machine:
Its very regular, is it Z wobble?
Is the extruder temp fluctuating?
Is the extruder drive gear partly clogged?

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

Thanks for the reply, the drive gear is not clogged and I intially thought the same thing. My filament drive is very robust and rarely slips or strips the filament. The z wobble doesn't appear to be the issue because the layer mis-alignment varies. Take a look at picture 837, the lower layers show more mis-alignment than the top. I auto-tuned the hotend temp and it doesn't fluctuate more than .5 degrees. I have been playing with the accel speeds and did show some improvement but have not totally elimated it. I am currently at 30 for XY jerk and 4000 accel. If I raise it too much more the motors cannot handle it

Picture 837 is very interesting.
It looks like the "wobble" is directly proportional to printing TIME, like a sine wave of increasing length - as each layer takes a bit less time than the one before as the part narrows.
So I ask myself, what is oscillating at a regular time interval?

- I think his rules out the z axis, as the distance between "wobbles" increases rapidly and proportionally to shorter layer time, not what I would think as typical Z wobble.

Do the layers get larger and smaller in all directions at once?

Or is each layer pushed over?

You've obviously checked about everything - do you have flats ground on the stepper shafts?

Perhaps someone with a CoreXY can comment further. Can you post a photo of your machine and controller?

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

Have you changed your layerhight?
It looks like your layerhight doesn't match your z-axis rod.
Use the prusa calculator to determine the right layerhights. [prusaprinters.org]

Layer height is 200um and is dead on using a digital dial indicator. I may have fixed some of the ringing on the corners by slowing my accel down to 1500, jerk setting to 20 and slowed my XY move speeds from 300 to 200. Printing test pieces now. Another question, how do you guys keep pointed overhangs from curling up due to heat using abs? I have been trying to print the gear heart on thingiverse but the gear tips curl up causing the head to hit it. The base of the gears are still firmly attached to the bed. I already lowered my temp down to 220 and my heated bet to 80.

I was getting to the end of my abs filament spool so it was changed to PLA. I forgot how easy PLA is to print! All the annoying problems of ABS are gone (sticking to the bed, layer delaminating, ect..) I just need to get a cooling fan to help with small parts. Anyways, the surface finish is much better but the corners still showing some blobs. Am I being to anal about the corners looking this way with a bowden setup?

Gforce, I checked my ball screw and it has a 5mm pitch coupled to a 2:1 drive making my steps per mm 1280 with 1/16" stepping. The calculator comes out to whole steps pretty much every thing I print (.05, .1, .15, .2). Here is some of the latest prints and some of my setup. The pictures of the die is what I used to be able to achieve but not sure what happen. I am hoping the filament went bad on me and I am chasing my tail.

[drive.google.com]

I know this is old but wanted to share what actually fixed my layer alignment issues. I was using a relay to switch my heated bed but was getting a 4C degree temp swings using this method. I finally upgraded to a solid state relay using PID control. My bed temp is now rock solid with only 0.2 degree swings. I have attached a pic showing the 2 on the left were printed with a relay and the 2 printed on the right were with a solid state relay for the heated bed.

Happy to have my beautiful layers back.
-Greg

Edited 2 time(s). Last edit at 04/05/2015 09:16AM by gadittri.