This can't be warped bed... can it?

[wckdawe 1]

Good morning to the community,

I've been trying to setup my Ender 3 V2 printer after moving to a different home.. It's been quite a long while since I've printed everything.

I reassembled the printer, installed Klipper for a change, but I can't seem to get why my Bed Graph looks like that!

 

It don't believe it is a bed issue. I removed the glass bed and placed a different one, but still got the same result. A similar pattern.
 

I took the following steps but non seemed to do any difference:

1. Changed the X-Gantry wheels with brand new ones (I suspected maybe one of the wheel could be warped, making this "wavy" pattern)
2. Re-tightened the BLTouch Clone sensor (It is a 3DTouch, but I have been using it quite a while and it was working pretty well with very accurate results)
3. Re-tightened the whole X-Gantry.

 

Additionally, I've tried to move the X-Gantry by hand (Turning the motor wheel to move it left and right slowly), and I did notice those small "up and down" waving pattern appear, by looking how close the nozzle was to the bed.

 

I'd love to have your feedback regarding this issue and hopefully find a potential fix. Yes, the BLTouch clone can compensate as much as it can for these issues... but it just doesn't seem right. I am sure there is a problem that should be fixed there.

 

Thanks in Advance!


P.S: Hello there @gr5 <3 Just a weird fan boi.

[GregValiant 1,250]

When you re-assembled the printer - did you use a tri-square or other tool to insure that XYZ are all at exactly 90° to each other and that the faces of the 20x40 Z uprights are parallel?   In particular, my Y was at an angle to both the Z and X axes as assembled by Creality.  That lead to both leveling issues (I hand level) and skewed prints.

Any piece of glass is pretty flat.  The X wheels could have been a problem as the nozzle is supposed to move smoothly across a plane.  The bed cannot have any wobble that might be caused by improperly tightened wheels on the carriage.

[wckdawe 1]

31 minutes ago, GregValiant said:

When you re-assembled the printer - did you use a tri-square or other tool to insure that XYZ are all at exactly 90° to each other and that the faces of the 20x40 Z uprights are parallel?   In particular, my Y was at an angle to both the Z and X axes as assembled by Creality.  That lead to both leveling issues (I hand level) and skewed prints.

Any piece of glass is pretty flat.  The X wheels could have been a problem as the nozzle is supposed to move smoothly across a plane.  The bed cannot have any wobble that might be caused by improperly tightened wheels on the carriage.

I do not have a tri-square unfortunately hanging around...

 

I used a big flat metallic ruler I had to make sure that the Z axis 20x40s were the same distance top and bottom, which they were. 

I did change the X-Wheels.. Twice to be certain, but it didn't seem to affect the irregularity of the pattern.
To be fair, it did change the pattern. 

 

(This is the OLD Wheels)

 

While this one (which is also the picture on the original post above), is the new wheels.

The probe points aren't the same, I think the old one was 8x6, while the newest picture is 6x4.. but still, a similar "irregular" pattern appears.

 

As for the bed, I made sure to tighten the eccentric nut as far as that there was no wobble to the table. It seems to be pretty stable!

 

I do believe that it is a "wheel-area" issue.. Could by any chance the eccentric nut to have somehow "failed"? Like if the circle inside the eccentric nut isn't perfect?

 

Thank you very much for your input! <3

Edited February 3, 2022 by wckdawe

[GregValiant 1,250]

The only problem I can envision with the eccentrics is if the cam outside diameter isn't engaged into the hole in the bracket.  That has happened on my re-assembly a couple of times.  Other than that, tight is tight and any clearance tolerance between the offset ID and the shoulder bolt OD should go away as you tighten the eccentric nut.  It's how they work.

I don't have an ABL so I'm hampered here.  Did you manually level the bed before testing the ABL?  I know it will make adjustments to the first layer to compensate, but your pattern sure looks like the bed is lower on the right.

[wckdawe 1]

4 minutes ago, GregValiant said:

The only problem I can envision with the eccentrics is if the cam outside diameter isn't engaged into the hole in the bracket.  That has happened on my re-assembly a couple of times.  Other than that, tight is tight and any clearance tolerance between the offset ID and the shoulder bolt OD should go away as you tighten the eccentric nut.  It's how they work.

I don't have an ABL so I'm hampered here.  Did you manually level the bed before testing the ABL?  I know it will make adjustments to the first layer to compensate, but your pattern sure looks like the bed is lower on the right.

You are correct here.

Indeed I usually bed-level manually before I print. That is not the case here, as I just wanted to take a quick photo of the irregular pattern. I was testing by placing aluminum foil between the glass bed and the aluminum plate, to see if there were any change in the pattern, which wasn't the case other than making the bed look not level in one side.

 

As for the Eccentric nut, I was wondering maybe if I did place something incorrectly? It looks like this:
 

Screw/Bolt Head --> Wheel --> Eccentric Nut --> Metal Plate -> Washer -> Nut

 

Should it maybe be: 
Screw/Bolt Head --> Wheel --> Eccentric Nut --> Washer --> Metal Plate --> Nut?

Where Metal Plate I mean this:

[GregValiant 1,250]

The first one is correct.

The height of the eccentric nut - not counting the height of the eccentric diameter - must be equal to the height of the spacers on the other wheels.  If they aren't then the X plate may rest at some small angle, but it will always be the same as it moves.  The same is true for the Y wheels.

There is always some tolerance in a switch (and the ABL gizmo is a switch) if for no other reason than "switch bounce" of it's internal contacts.  That should be so miniscule that you can ignore it.

If you start with a couple of premises:

• The glass is flat.
• The nozzle moves exactly planar.
• Every G28 changes the location of Z = 0.

That Z location is totally dependent on the repeatability of the Z switch.  I had to swap my Y and Z switches because the Z was off by up to .5mm from one Auto-Home to the next.  It made the variation of the first layer thickness really hard to get right.  Now I Auto-Home, then level, and the Startup Gcode has G28 X Y so the Z doesn't Home (or change) between leveling and the start of the print.  It's a lot more consistent than it was.

Leveling the bed manually moves the bed to the plane the nozzle travels on when Z = 0.  It should be even-steven all the way across.  It's a plane.  The ABL measures the plane of the top of the build surface and calculates where it is in relation to the plane the nozzle travels on.  Somehow (magic may be involved) an adjustment is made so the first layer is correct.  That adjustment does nothing to fix an angled plate or X axis.  The parts will be skewed however slightly, but they will print.

 

You did mention the X beam and that it is tight.  How about the Z wheels?  An Auto-Home causes the Z to move.  If there is something that is causing the right end to lag behind the left end, or to hang, then the X will be at a slight angle and the bed leveling data will reflect that.

[wckdawe 1]

27 minutes ago, GregValiant said:

The first one is correct.

The height of the eccentric nut - not counting the height of the eccentric diameter - must be equal to the height of the spacers on the other wheels.  If they aren't then the X plate may rest at some small angle, but it will always be the same as it moves.  The same is true for the Y wheels.

There is always some tolerance in a switch (and the ABL gizmo is a switch) if for no other reason than "switch bounce" of it's internal contacts.  That should be so miniscule that you can ignore it.

If you start with a couple of premises:

• The glass is flat.
• The nozzle moves exactly planar.
• Every G28 changes the location of Z = 0.

That Z location is totally dependent on the repeatability of the Z switch.  I had to swap my Y and Z switches because the Z was off by up to .5mm from one Auto-Home to the next.  It made the variation of the first layer thickness really hard to get right.  Now I Auto-Home, then level, and the Startup Gcode has G28 X Y so the Z doesn't Home (or change) between leveling and the start of the print.  It's a lot more consistent than it was.

Leveling the bed manually moves the bed to the plane the nozzle travels on when Z = 0.  It should be even-steven all the way across.  It's a plane.  The ABL measures the plane of the top of the build surface and calculates where it is in relation to the plane the nozzle travels on.  Somehow (magic may be involved) an adjustment is made so the first layer is correct.  That adjustment does nothing to fix an angled plate or X axis.  The parts will be skewed however slightly, but they will print.

 

You did mention the X beam and that it is tight.  How about the Z wheels?  An Auto-Home causes the Z to move.  If there is something that is causing the right end to lag behind the left end, or to hang, then the X will be at a slight angle and the bed leveling data will reflect that.

 

Thank you for verifying the Eccentric nut placement!

 

So, I went home and did a little test. With the printer power off, I set the Z height manually. Then I only moved the Y Axis. I noticed a similar pattern there. To verify it wasn't the glass for any reason other than my craziness, I rotate the glass 4 times and did the same thing, moving only the Y axis (I didn't move X, Z at all even while changing the glass). 

So lets consider my X/Y Axis was ok, with no issues at all. Then,
 

Agreeing on your premises and focusing on the Y axis this time only:

• The glass is flat.
• The nozzle moves exactly planar.
• Every G28 changes the location of Z = 0.
• Plus: Z, X is stationary.

What could cause that bouncing around. My hypotheses:

1. Bad wheels -- But in this case, I did change the wheels twice with the same result.
2. Something is bent?
3. Absolutely nothing else coming to my mind.

I did take some photos/videos maybe to assist as much as they can.

So, again, keep in mind.

• Power is off
• I move the Y axis by turning the wheel Y Axis wheel that has the synchronous belt, without touching the bed or the wheels of the bed at all.
• The springs are relaxed because I am going to probably disassemble the printer and investigate further... but same thing happens when the springs are fully or almost fully tightened.

Video Moving the Y Axis (Couldn't upload it here either as mp4 nor gif for some reason :/ ) https://www.dropbox.com/s/3gey6ebvzf8j0o6/video-1643895442.mp4

[GregValiant 1,250]

Well...that isn't good.  Either the glass is out of a carnival funhouse, or something is wrong with the Y wheels, or the Y beam extrusion.  I'll think on this, but all you did was move the machine?  It's hard to believe that something as robust as the main Y extrusion would have a problem and you have been over the wheels a couple of times.  You have closely inspected the Y trolley grooves?  No mouse in there?

 

How does it print?  Is the first layer sticking or is the error too much?

[wckdawe 1]

8 hours ago, GregValiant said:

Well...that isn't good.  Either the glass is out of a carnival funhouse, or something is wrong with the Y wheels, or the Y beam extrusion.  I'll think on this, but all you did was move the machine?  It's hard to believe that something as robust as the main Y extrusion would have a problem and you have been over the wheels a couple of times.  You have closely inspected the Y trolley grooves?  No mouse in there?

 

How does it print?  Is the first layer sticking or is the error too much?

Good morning,
Brand new day.. brand new time to figure out the problem... When work is done of course... but you get what I'm saying!

I do not think it is the glass, as I've tried a different one with similar results. Also rotating the glass doesn't change anything. Same exact pattern, same place.

Yesterday, I did again try the following:

1. Cleaned the Y Axis with Isopropyl alcohol
2. Reassembled the Y Axis (but with same wheels).

When I come back from work today I'll disassemble the whole Y Extrusion, clean it again as much as I can and reinstall it. Do you have any recommendations on Cleaning it? Since it will be far away of the electronics can I wipe it down with water made, and then make sure it is dry when placed back?

 

On the video all I did was move the Y Axis by rotating the wheel with the rubber sync belt, not touching the bed at all. If you are asking about when I moved the whole printer from house to house, I disassembled it, repackaged it in its original case and moved it. Didn't really get any damage there. Actually it was one of my most careful items moved :P 

 

I'll let you know if I have any results after fully disassembling the Y axes!

Thanks again for your support and effort on this matter

[GregValiant 1,250]

Something else to think about...

When I first started out with my 3 Pro, a LOT of lint, and dust, and filament strings, collected on the wheels.  I would clean them off occasionally just using a cloth and isopropyl alcohol.  The wheel slots were cleaned the same way.

About a year after I got the printer, I heard a squeak.  I pulled the wheels off each axis in turn and spun them to check the bearings.  There were a couple on each axis that were glitchy.  Since the bearings aren't sealed, I sprayed each generously with WD-40 and spun each vigorously to flush out the bearings.  I blew each out with an air compressor, worked in a light lubricating oil, and the "glitchiness" and the squeak were gone.

That has become part of my preventative maintenance routine.  I pull the wheels every 4 months or so and check the alignment of the axes to make sure nothing has changed.  Does it help?  I don't know.  It makes me feel better though as I know if I have to troubleshoot a condition - the axis alignment and wheels aren't the problem.

[wckdawe 1]

On 2/4/2022 at 1:45 PM, GregValiant said:

Something else to think about...

When I first started out with my 3 Pro, a LOT of lint, and dust, and filament strings, collected on the wheels.  I would clean them off occasionally just using a cloth and isopropyl alcohol.  The wheel slots were cleaned the same way.

About a year after I got the printer, I heard a squeak.  I pulled the wheels off each axis in turn and spun them to check the bearings.  There were a couple on each axis that were glitchy.  Since the bearings aren't sealed, I sprayed each generously with WD-40 and spun each vigorously to flush out the bearings.  I blew each out with an air compressor, worked in a light lubricating oil, and the "glitchiness" and the squeak were gone.

That has become part of my preventative maintenance routine.  I pull the wheels every 4 months or so and check the alignment of the axes to make sure nothing has changed.  Does it help?  I don't know.  It makes me feel better though as I know if I have to troubleshoot a condition - the axis alignment and wheels aren't the problem.

 

Good morning/evening m8!
 

I hope you are having a wonderful weekend. So.. I ended up disassembling the whole printer and rebuilding it. 

I do understand the squeakiness you are talking about, I have felt it before on the same printer, but I thought it was a bad wheel! I'll definitely try that next time... No wheels should go to waste.

 

So I still have no idea what is/was causing the issue.. but after reassembling the whole printer from 0 to 100, I ended up with this graph.

 

It is still not perfectly flat.. but it is quite better than before. Now, if you look closely you can see the wave is still there (or I am being paranoid..) so I do not think the underline issue is fixed.
Alternately, could this be just the probing deviation?

 

 

And the probing results from PROBE_ACCURACY through Klipper (10 Probes on same position)

16:14:24 // PROBE_ACCURACY at X:117.500 Y:117.500 Z:10.000 (samples=10 retract=2.000 speed=5.0 lift_speed=5.0)
16:14:27 // probe at 117.500,117.500 is z=2.202000
16:14:30 // probe at 117.500,117.500 is z=2.202000
16:14:32 // probe at 117.500,117.500 is z=2.199500
16:14:35 // probe at 117.500,117.500 is z=2.202000
16:14:38 // probe at 117.500,117.500 is z=2.184500
16:14:40 // probe at 117.500,117.500 is z=2.202000
16:14:43 // probe at 117.500,117.500 is z=2.187000
16:14:45 // probe at 117.500,117.500 is z=2.184500
16:14:48 // probe at 117.500,117.500 is z=2.187000
16:14:51 // probe at 117.500,117.500 is z=2.187000
16:14:51 // probe accuracy results: maximum 2.202000, minimum 2.184500, range 0.017500, average 2.193750, median 2.193250, standard deviation 0.007830

 

I haven't yet printed anything.. I'll give it a try as soon as I can.

Just wanted to give you an update ^_^

Have a nice weekend! Awaiting for your feedback

[GregValiant 1,250]

That is a lot better.

The "single position probe test" is interesting.  The probed switch repeatability would seem to be +/-.008.  If the regular bed probing numbers are within that tolerance across the surface that's about the best you can get with the equipment you have.

It's time for you to print something.

[wckdawe 1]

16 minutes ago, GregValiant said:

That is a lot better.

The "single position probe test" is interesting.  The probed switch repeatability would seem to be +/-.008.  If the regular bed probing numbers are within that tolerance across the surface that's about the best you can get with the equipment you have.

It's time for you to print something.

 

Awesome possum!

 

I'll go ahead and limit back down to a 3x3 Grid I guess and do some prints within the day hopefully!

Thanks a lot for keeping me company while troubleshooting this issue.. I really would love to had actually figured out what the problem is instead of going "brute-force" method and rebuilding the whole thing :P

Have a nice rest of the weekend!