Irregularity on X and Y on some layers

[thomasrtg 0]

Hi everyone !

 

I have just received my anycubic chiron which is my first 3D printer. I have set it up and print some calibration parts, and since then, I cannot solve an issue I am having on each print.

At first I have looked and tweak a lot of settings on Cura such as speed, layer height, printing strategy and other. The prints have become better and better but I am having an issue that I cannot fix. 

 

It seems that the printer is doing wider or thinner section, this issue is happening every time at the same height. I have also tried to print other parts and they always have the exact same problems. 

 

I have tried to use another slicer with the same setting, which had not effect, that is why I am thinking that the issue is a hardware one and not a software one.

 

As the problems are happening at the same height, I have tried to turn over my Z screws over (bottom at the top and top at the bottom), but it had no effect at all. I have tried different temperatures for both bed and extrusion, but it had no effect. I have tried with rafts, but no effect either.

I start to be lost...

Should I contact anycubic for warranty or do you think is only a setup issue ?

 

I hope my explanations are clear..😄

 

I have linked picture of these parts, and I can take some more if needed.

 

Thanks in  advance !

 

Thomas

 

 

[thomasrtg 0]

Hi everyone it is me again 

 

I posting more pictures of another part I have printed. 

 

The beginning of the parts is not regular and at some point it became good. It became nice at the same height as with the calibration cubes I have posted on the previous post. 

The red line indicates the bottom of the printbed. 

 

 

[thomasrtg 0]

Anyone 😢? 

[GregValiant 1,250]

Hello,

You have a complicated Z system and I think you need to visit it.

You have dual Z motors.  Each is attached to the frame at 3 points.  Those 3 points (output shaft, brass nut, top bracket) must be exactly in line or you can get binding.  Additionally, that's a big frame and the X beam needs to travel freely without binding or wobbling.  It's a juggling act to get them all working together.

 

My Ender is a single lead screw without a top support.  It needed 0.3mm of shim behind the Z motor mount to make the lead screw straight up and down.  Your top brackets complicate things.

I guess what I would do is put a book or something on the bed to support the cross beam, and take out the screws that hold the brass nuts to the cross beam bracket.  Take measurements of the distance from the left upright to the top of the lead screw, and from the left upright to the bottom of the lead screw right above the motor.  They should be the same.  If they aren't, you may need some shims to insure that the lead screw is parallel to the adjacent upright.  You will need to do the same thing for the right lead screw.  (The left measurement doesn't have to be equal to the right measurement.)  Then when you put the brass nuts back in place and put their screws back in, they should fit nicely with no binding.

 

Dry lubricants are recommended for the lead screws.  You can get them at an auto-parts store or hardware store.  It wouldn't hurt to lube the rods, but if they pick up dirt and dust you will get a binding problem again.

 

Dual lead screws need to be clocked correctly.  They need to pick up the X beam at exactly the same time.  That can be as simple as loosening the coupler set screws and turning each lead screw to take up any backlash and then re-tightening the set screws.

 

 

 

[thomasrtg 0]

On 1/23/2021 at 3:27 PM, GregValiant said:

Hello,

You have a complicated Z system and I think you need to visit it.

You have dual Z motors.  Each is attached to the frame at 3 points.  Those 3 points (output shaft, brass nut, top bracket) must be exactly in line or you can get binding.  Additionally, that's a big frame and the X beam needs to travel freely without binding or wobbling.  It's a juggling act to get them all working together.

 

My Ender is a single lead screw without a top support.  It needed 0.3mm of shim behind the Z motor mount to make the lead screw straight up and down.  Your top brackets complicate things.

I guess what I would do is put a book or something on the bed to support the cross beam, and take out the screws that hold the brass nuts to the cross beam bracket.  Take measurements of the distance from the left upright to the top of the lead screw, and from the left upright to the bottom of the lead screw right above the motor.  They should be the same.  If they aren't, you may need some shims to insure that the lead screw is parallel to the adjacent upright.  You will need to do the same thing for the right lead screw.  (The left measurement doesn't have to be equal to the right measurement.)  Then when you put the brass nuts back in place and put their screws back in, they should fit nicely with no binding.

 

Dry lubricants are recommended for the lead screws.  You can get them at an auto-parts store or hardware store.  It wouldn't hurt to lube the rods, but if they pick up dirt and dust you will get a binding problem again.

 

Dual lead screws need to be clocked correctly.  They need to pick up the X beam at exactly the same time.  That can be as simple as loosening the coupler set screws and turning each lead screw to take up any backlash and then re-tightening the set screws.

 

 

 

Thank you very much for your answer I will definitely try to take a look at it. I can't look at it right now but I will as soon as I can and let you know. 

 

I have disabled the Z screws again to check how easy the Z axis could move. It appeared that it is kind of normal smooth BUT I found that every wheel revolution it was making an awful noise and that I could feel a "bump". 

 

I looked every wheels and one looks damaged. I have uploaded a picture of it so yoy can see. 

 

To check if that was the issue causing the problem I had, I have put the printer back together and print a 20 x 20 x 200mm rectangular parralelepiped. The results are kind of weird.. There is not issue at all with this print. I don't understand what I did but the printer seems to print well now (even with the damage wheel). There is only overshoot problem but I have a used a fast printing speed to get a result quick enough. 

 

What do you think about it? 

[GregValiant 1,250]

The angled part of the wheel is in shadow so I can't see it.  The working part of the wheel is the angled area (as it moves in the track).  If those slice marks do not extend onto the angled portion then it is not an issue.

 

The print looks good.  Overshoot can be caused by loose belts or other forms of backlash as well has high print speeds.  Enabling Accel and Jerk control with low values (like 500 Accel and 8 Jerk) can help by slowing the print head before a turn, but with short runs like on that part it doesn't come into play very much (unless you have Accel and Jerk control turned off which makes Accel and Jerk essentially infinite).  Ultimaker printers can handle high Accel and Jerk settings but the rest of us need to slow down.

 

There is still a bit of elephant foot there (wide at the build plate).  You can use Initial Layer Horizontal Expansion to mitigate that.  On my printer a setting of -0.25 works well for most prints.  That makes the first layer .25 smaller all the way around.

 

 

 

[thomasrtg 0]

On 1/26/2021 at 3:21 PM, GregValiant said:

The angled part of the wheel is in shadow so I can't see it.  The working part of the wheel is the angled area (as it moves in the track).  If those slice marks do not extend onto the angled portion then it is not an issue.

 

The print looks good.  Overshoot can be caused by loose belts or other forms of backlash as well has high print speeds.  Enabling Accel and Jerk control with low values (like 500 Accel and 8 Jerk) can help by slowing the print head before a turn, but with short runs like on that part it doesn't come into play very much (unless you have Accel and Jerk control turned off which makes Accel and Jerk essentially infinite).  Ultimaker printers can handle high Accel and Jerk settings but the rest of us need to slow down.

 

There is still a bit of elephant foot there (wide at the build plate).  You can use Initial Layer Horizontal Expansion to mitigate that.  On my printer a setting of -0.25 works well for most prints.  That makes the first layer .25 smaller all the way around.

 

 

 

 

Hi, I am pretty sure I need to adjust the tension of my belts and decrease the acceleration and jerk to the settings you advised me. 

 

I have taken another picture but I am not sure that it is a better one 😅. 

 

Here is a video of the Z axis manually actuated (not smooth at all). 

 

 

 

Edited January 28, 2021 by thomasrtg
I uploaded a video on YouTube to show the Z axis movement

[GregValiant 1,250]

Every month or so, I give my printer a good cleaning and check the wheel pressure in the guide slots, Z coupler screws, trim the bowden tube, calibrate the E stepper, etc.  It helps keep the machine running in good order, and it keeps me up-to-date with any problems that might be developing.  It's kind of like kicking the car tires and cleaning the windshield.  

 

In regards to the marks on that wheel, I don't see them extending to the wear area on the angled sides so they aren't a problem.

 

Next is the jerkiness of the Z movement, I see you have the lead screws out, so that jerkiness isn't good.  If you loosen the right and left adjustable eccentric wheels to allow sloppy movement, I would expect the jerkiness to go away.  When the wheels are adjusted correctly, you can just turn them with your fingers.  If you can't rotate them at all they are too tight.  If they spin freely they are too loose.  I'm sure you can find good videos on adjusting the wheels. 

 

Adjust the pressure of the Z wheels when the X beam is all the way to the bottom, then loosen the top cross bar on one side, and move the X beam to the top, then re-tighten the top cross beam, that's about as good as you can do.  It insures that the two upright aluminum pieces are parallel.  If you still have herky-jerky movement after that, it may indeed be the wheels.  I took mine off and sprayed them all down with silicone lube after a year of running hard.  I don't know that it made a difference, but it made me felt better.

[thomasrtg 0]

Hi, Sorry I was in holidays and therefore could not use the printer .

 

I have done adjusted the tension of the belts, each eccentric wheels and now the prints are much better !

 

I still have an issue but it is totally different from what I had, I think I am going to do a new post for it.

Thank you very much for your help it has been really useful !