I have a new Creality Ender 3.

I suspect that I have not adjusted the eccentric nuts correctly, on the X-axis head carriage mounts.

Even after a glass bed upgrade, using the Level Corners routine of the TH3D firmware, I can get the head to scrape a sheet of paper all 4 corners but that same sheet of paper does not then scrape the head in the center, unless I fold that paper in half.

I could understand this if the rail on which the hot end travels is very slightly higher at the side opposite the extruder. I have tried turning the eccentric nut on that side until the head does trap the paper, but when I then repeat the Level Corners routine, the gap at the center has come right back.

I already adjusted the eccentric nut on the extruder end because the wheels on the hot end carriage were showing an accumulation of brown dust in a ring around each wheel, which I heard was likely a sign that the carriage was "too tight." So basically, I am messing around with the eccentric nuts at both ends of the X-axis rail, chasing two problems at the same time, but I don't really know what I am doing.


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    $\begingroup$ Could be a bent x axis rail? Are the gaps at center x independent of y? $\endgroup$ Commented May 19, 2019 at 2:45
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    $\begingroup$ Is the glass flat? Put a metal ruler on its side to check. There are known slates of glass that are not flat. A BLTouch sensor could help out in such cases. Please edit your question to tell if the glass is flat or not. Else you need to look at the X carriage linear support rail! $\endgroup$
    – 0scar
    Commented May 21, 2019 at 6:27
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    $\begingroup$ I'm voting to close this question as it appears to be abandoned by the OP as repeated requests for information are not answered. This question is not answerable without more information. $\endgroup$
    – 0scar
    Commented May 25, 2019 at 5:24
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    $\begingroup$ Try flipping the glass over, and see if it now bulges up in the middle. You may simply need to replace the glass or try another build surface. $\endgroup$
    – Criggie
    Commented Oct 12, 2021 at 23:24

3 Answers 3


This seems to be a common problem with ender-3 and cr-10 printers from Creality. Mine is the same way but not enough to keep prints from adhering.

Typically the aluminum bed is not perfectly flat. If it’s not the glass may be able to flex enough that it can make a difference. There are a few ways to try to fix it.

  1. Shim the low spots in the aluminum bed with aluminum foil or another thin material. Then the glass will sit on a flatter more well supported surface.

  2. Bend the aluminum bed until it is flat.

  3. Add a 5th leveling point under the middle of the bed. You could either make it adjustable which would be tricky to get to or create a support piece accurately or get one close and shim it.

The shimming process is probably the easiest and the one I may end up doing. But whether you shim it or do the other trick you need to measure for points that are out of flat.

If you get a decent straightedge and some feeler gauges and/or or shine a bright light from the other side and look for spots of light between the straightedge and the aluminum bed you can see where you need to shim or otherwise adjust it. You’ll need to move it at various angles through the center and other spots on the bed. That way you can see whether it is just the middle or if the edges are an issue too.

Also, once you check the aluminum bed, check the glass as it may not be flat either.

There was a YouTube video on the cr-10 I think that showed part of the shimming process and checking for level. I’ll try to see if I can find it to add a link here.

I still didn't find the video I was looking for, but here is a useful related one that talks about tramming the bed (what 3d printing people call leveling) https://www.youtube.com/watch?v=CcAmZqb-ZEE

And here's a reddit thread about the issue. Someone incorrectly says the glass plate can't flex that much but it certainly can. We're talking small tolerances. Even granite slabs flex small amounts. https://www.reddit.com/r/CR10/comments/7d7gyh/aluminum_bed_warped_cant_get_it_to_do_anything/

  • $\begingroup$ I used 6cm squares of foil in the center. Foil is ~10x thinner than paper, so I ended up using about 24 layers (6 strips folded in half twice) to get mine dialed in. $\endgroup$ Commented Oct 25, 2020 at 0:19

I had the same problem with an Ender 3 out of the box. I ended up adding a thin raft under each print. This would solve it if you don't want to do the manual adjusting.


I had the same exact issue, you have to make sure all of your printer is leveled, start with the base, than the poles that hold your x axis gantry. there are numerous youtube videos on how to do that.. make sure it's all leveled and try again.. this tip helped a few people already

  • $\begingroup$ I'm not sure why people downvoted my answer, it's what made my printer and numerous others work, i had 2 weeks of researching till i found out this is the actual problem, you have to reset it all $\endgroup$
    – Pixel
    Commented Dec 11, 2021 at 20:13

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