# Bed mesh "bump", what could it be? **URL:** \ **Category:** General Discussion\ **Created:** [January 28, 2024, 3:24pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595 "2024-01-28T15:24:47Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Kilohertz](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Kilohertz](https://klipper.discourse.group/u/Kilohertz)\ **Post date:** [January 28, 2024, 3:24pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/1 "2024-01-28T15:24:47Z")
### Basic Information: Ender 3 Printer Model: S1 PRO MCU / Printerboard: R Pi `klippy.log` [Unconfirmed 832850.txt](https://klipper.discourse.group/uploads/short-url/dlTth7l0RzpYKpnxXuj60wDwxCd.txt) (986.3 KB) _Fill out above information and_ **_in all cases attach your_ `klippy.log` _file_** (use zip to compress it, if too big). _Pasting your_ `printer.cfg` _is **not** needed_ _ **Be sure to check our “Knowledge Base” Category first. Most relevant items, e.g. error messages, are covered there** _ ### Describe your issue: … Good day everyone. This is my first 3d printer and installed Klipper after playing with Marlin for a week. I’ve had Klipper running for 2 days and am figuring things out and really liking all the features it offers. I found last night the bed mesh viewer. very cool, and noticed a “bump” in the image. I tried the following things to determine where the anomaly is originating but no matter what I do, it remains. I rotated the PEI sheet, removed the PEI sheet, then did both again with a hot bed 65\*. Max deviation is .213mm. Anybody else have similar results and is this anything to worry about? Thoughts on how to correct it? Thank you. ![ender bed mesh](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/e/eabd8cde25fe14b83d66cbc36c469284d81a8ef0.jpeg) ---
**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\ **Post date:** [January 28, 2024, 6:27pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/2 "2024-01-28T18:27:54Z")
Hello @Kilohertz ! Have you checked for obstacles between bed and PEI sheet? ---
**Author:** ![Kilohertz](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Kilohertz](https://klipper.discourse.group/u/Kilohertz)\ **Post date:** [January 28, 2024, 7:15pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/3 "2024-01-28T19:15:36Z")
Yes, I pulled the PEI sheet and looked for any little particles, nothing, but I also ran the bed mesh without the sheet, with it rotated and it made no difference, the profile looks pretty much the same for all scenarios. Thanks ---
**Author:** ![theophile](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/theophile/32/31_2.png) [@theophile](https://klipper.discourse.group/u/theophile)\ **Post date:** [January 28, 2024, 7:27pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/4 "2024-01-28T19:27:11Z")
Foreign object on the X gantry that slightly displaces the roller? You could temporarily increase the mesh resolution to see how wide an area is affected. ---
**Author:** ![Kilohertz](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Kilohertz](https://klipper.discourse.group/u/Kilohertz)\ **Post date:** [January 28, 2024, 9:21pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/5 "2024-01-28T21:21:55Z")
Okay thank you. I modded the print.cfg file for a 16x12 bed mesh and ran it, immediately something jumped out at me, there are now 3 lumps, front to back back along the Y axis. I thought about it, bed width is 220mm, the spacing of the lump peaks are exactly 71mm apart for all three, the diameter of the rollers where they ride are 22mm, the circumference of the rollers is 71mm…Mmmmm, there is a roller that is not quite round as it’s not a sharp peak, it ramps up to a peak so it won’t be a pebble or xxx, I’ll try cleaning first, any other thoughts? Thanks for asking me to refine the bed mesh, cool results. Cheers ![bed mesh 16x12](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/4/40561dc62066c1d29292fc62e91d149b8be170e3.jpeg) ---
**Author:** ![theophile](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/theophile/32/31_2.png) [@theophile](https://klipper.discourse.group/u/theophile)\ **Post date:** [January 28, 2024, 9:50pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/6 "2024-01-28T21:50:11Z")
Yep, sounds like your culprit. Wiping the rollers and the gantry surface down is worth trying. You can also try to manually turn one of the top rollers by hand about 180 degrees so that it is out of “phase” with the other roller, just in case the two have developed a uniform deformation. If so, then rotating one roller and not the other can sometimes help to make the effect of the deformation less pronounced. Either way, unless cleaning resolves the problem, it’s probably worth getting some replacement delrin rollers. ---
**Author:** ![Kilohertz](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Kilohertz](https://klipper.discourse.group/u/Kilohertz)\ **Post date:** [January 28, 2024, 10:05pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/7 "2024-01-28T22:05:47Z")
30 seconds after I posted my son suggested turning 1 roller at a time about 45\*, then test again, we did that 3 times and it’s the bottom roller, the top two made no difference. The printer works perfectly, is this something that should be resolved or I am chasing a measurement “just because I can”? I will go through and clean everything, it’s only a week old but could be something from the factory. Are Delrin rollers upgrades from stock? Thanks for your help. PS while I have your attention, is there a program, macro, file or ?? that will allow me to adjust the corner screws similar to the way the stock Creality/Marlin allows to to “paper test” in 5 spots on the bed but in Klipper? I don’t want to reflash Marlin just to do a mechanical bed level. thx ![bed mesh 16x12 rollers moved](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/7/7cbcb38ff26301f1ccc9a7101417f4b56285fb19.jpeg) ---
**Author:** ![LifeOfBrian](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/lifeofbrian/32/2380_2.png) [@LifeOfBrian](https://klipper.discourse.group/u/LifeOfBrian)\ **Post date:** [January 28, 2024, 10:09pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/8 "2024-01-28T22:09:59Z")
Something like that: [https://www.klipper3d.org/Config\_Reference.html#screws\_tilt\_adjust](https://www.klipper3d.org/Config_Reference.html#screws_tilt_adjust) ---
**Author:** ![Kilohertz](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Kilohertz](https://klipper.discourse.group/u/Kilohertz)\ **Post date:** [January 28, 2024, 11:26pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/9 "2024-01-28T23:26:46Z")
Thanks, I’ll check out the link. Well this is the best I can get the bed level, ignoring the bumps we are discussing, I’m getting a max deviation of .145mm, I think that is 145 microns? I read somewhere we should be shooting for 25 microns max, is that correct? Going to start looking for new rollers. Thanks again. Cheers ![tuned bed screws](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/4/4c6c9159b8f50afbddc33a0a626d23017e17e00c.jpeg) ---
**Author:** ![theophile](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/theophile/32/31_2.png) [@theophile](https://klipper.discourse.group/u/theophile)\ **Post date:** [January 29, 2024, 5:47pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/10 "2024-01-29T17:47:21Z")
Yeah, I would try to address that. 0.145mm is nearly 75% of the “standard” layer height of 0.2mm so the max deviation is almost the thickness of a “standard” layer. Also, the bed mesh is intended to compensate for a build surface that isn’t perfectly flat, not to compensate for mechanical flaws in the printer’s motion system. Yes, it can help partially conceal the issue with the deformed roller but can result in reduced dimensional accuracy and consistency. ---
**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\ **Post date:** [January 29, 2024, 5:58pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/11 "2024-01-29T17:58:46Z")
> [@theophile](#): > > Yes, it can help partially conceal the issue with the deformed roller but can Due to the probe’s offsets, there is a good chance that it might make it even worse: - Assume the probe snapshots a point when the roller is at its flat spot - When the nozzle is at the same coordinate, the roller might be at its maximum ---
**Author:** ![theophile](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/theophile/32/31_2.png) [@theophile](https://klipper.discourse.group/u/theophile)\ **Post date:** [January 29, 2024, 6:06pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/12 "2024-01-29T18:06:46Z")
Excellent point! In this regard it would be a similar phenomenon to the gantry twist issue insofar as calculating a mesh with a problematic motion system actually amplifies the problem. In essence, the “spikes” on your mesh will actually be translated in the X coordinate according to your probe offset since they were caused by the motion system and not the bed itself. This may result in two sets of problem spots: One wherever the flat spots on the roller actually are, and the other where where the mesh erroneously _thinks_ they are due to the probe offset. ---
**Author:** ![Kilohertz](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Kilohertz](https://klipper.discourse.group/u/Kilohertz)\ **Post date:** [January 29, 2024, 6:29pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/13 "2024-01-29T18:29:42Z")
Thanks guys, I have a set of new rollers on order, should be here Thursday. I appreciate the help. Cheers PS, I’ll post again after I replace the roller and hopefully resolve the issue. ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [March 29, 2024, 6:30pm UTC](https://klipper.discourse.group/t/bed-mesh-bump-what-could-it-be/13595/14 "2024-03-29T18:30:26Z")
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