linear bearing backlash, big X axis issues


I’ve been printing with my TAZ 4 for a few months now, very happy by the quality and build volume.

I came into serious issues with print quality very recently, let’s say in the past 2 weeks. I started to notice some oozing on the side of parts, usually when doing curved part.

that was new to me, as I printed a lot of parts, including complex quadcopter parts, a full flexidually head (not finished yet, about to install the steppers on it) and more.
Looking at the parts, I could see a scallop / wavy pattern in most of the curves, like if the thing was wobbling, which was definitely new, as quality of the prints were really perfect so far.

I started to look at the printing head and noticed I have a huge backlash on the linear bearings. There’s almost nothing on the left side, but it’s big and noticeable on the right side, and now I can see (and hear) the head wobbling while printing.

here’s a video of it :

I looked at the IGUS product page to see how those work, they are said to be oversized bearings that you pressfit and it should grab the lead shaft. In my case it’s not grabbing it at all.

2 possibilities IMHO :

  • bearings are dead. No idea how / why. The printer mileage isn’t crazy, I got it 5 months ago. I don’t even print 1 part a week with it.

  • the bearing housing / clamping on the X carriage opened up, mostly on the right side, but why less on the left side (?)

Printed didn’t get modded. I’ve experimented a couple of times with hight accelerations to check print speed on long parts but I’m back to the default back. I print with the bed at 95° and nozzle at 235°C with ABS from lulzbot.

pointers / hints ???

I also see that lulzbot sells some bronze bushing, similar to what I have on my UM1 at work. Should I move to this ? I don’t mind upgrading but I’m not happy with having the bearings or X carriage failing with no reason for now.

We do use those bearings, and printed bearing holders. To eliminate what you’re seeing you’ll need to loosen the screws securing the bearing holders, then slide them closer to each other (towards the imaginary midpoint between the two). Once closer, tighten them, without over-tightening. Once tightened check that the movement is still smooth along that axis. That should eliminate any of the rotational play you encountered.


I noticed that you indicated that the bar that moves the nozzle along the x axis was loose. Did this translate into prints that skewed along the y axis? Like this?

I am having a consistent problem with prints turning out like this. I have only had one of 9 attempts with the octopus print come out nearly flawless. All others skewed the filament along the y axis (nozzle deflection could explain this) and I have run into a battery of problems with loose set screws on plastic gears.

I too was not happy with the amount of deflection with the nozzle mount but being new to the platform, I dismissed it as an acceptable amount of play.

Skewing on any axis like the one pictured is going to be due to either the belts or pulley being loose. How tight does the belt feel? When powered, and paused while printing, you shouldn’t be able to move either axis. The stepper motors should lock in place, until you press “Motors Off”.

thank you for your answers. I don’t have any skew in my prints which were really perfect until recently like I said in the first post. Belts are tight, no slipping pulley or bearing.

@orias : thanks for the tip. So it means my bearing holders aren’t tight enough ?
What I don’t understand is that I don’t have any screws to adjust the pressure on the bearings. The holder has a stopper that prevents them to get even closer.

so, if I need to print an upgrade for that bearing holder, which one should I use ? linky to some thingiverse parts ?

any point of view on the bronze bushings to replace the polymer bearings ? are there some people here using those ?

You won’t be putting pressure on the bearings, you’ll be moving the bearing holders closer to each other/or farther apart. Are you able to do so?

I can’t move them. They have a fixed position on the X carriage. I have 3 bearings total. 2 on top, 1 on the bottom. The bottom seems to the be one really loose. It doesn’t have an open styled holder, it’s a full saddle covering it.
need pics ?

do I need to print a replacement part ?

Pics would be great if you can.


here’s how the X carriage looks like from the back (see attachement)

If you can’t squeeze the two bearing holders closer to the mid-line point between them, you can pull them farther apart to take up any slack.

Also is the cable tie on the wire rout always off?

iti didn’t change anything. It’s really like the IGUS bearing ID is now too large, and I have ZERO idea why.

I have ordered spares, 4 total, so that I can use a new carriage mount for better guiding, and if that fails agains, I’ll use the bronze bushings.

It’s mentioned in a couple of places that the IGUS have backlash. No one else with such an issue ?

I replaced the IGUS bearings with LMU10 Linear Bearings on my X-Axis (along with new, hardened Rods) in anticipation of the Dual Extruder and what a difference it made. The IGUS Bearings are a terrible fit. They are way too large on the interior and have far too much slop. My X-Axis wobbled like crazy. Now, the X slides smoothly and has no wobble whatsoever.

My Y-Axes started rattling on fast, thin infills (insides of walls). I checked the IGUS Bearings and they too were oversized and wobbling. So, I replaced them with LMU10 Linear Bearings, along with hardened Rods, and now the Y is as smooth as butter.

Now I’m thinking about replacing the X Bearings and Rods with 12mm versions to try and eliminate the sagging in the middle.


I finally looked under the printing plate just to discover the Igus are suffering from the same thing. Not as bad as some of the X carriage, but visible backlash just by the eye.

I looked at other topic regarding the upgrade with better bearings, I’m going to order some material today.

I still don’t know if mine were oversized first place or if it’s unwanted wear / aging. From what people have posted here and elsewhere they just seem to be not fitting / oversized.

thanks again for the help

The IGUS parts are just loose.

You can take all the slop out of the Y axis by loosening the bearing carriers and twisting them a little in the x axis direction. Mine were horribly loose when I received the Taz but this twist fix cured it. That was a year ago and still no problem with the Y.

My X carriage exhibits the same slop that many here have commented on. I have not bothered to do anything with it because when I move the carriage with the belt, it does not cause the carriage to rock or move the way it does if you twist and move the carriage by hand. I think this is due to the fact that the belt is pulling on the center line of the carriage and does not impart any twisting forces on the assembly. All that might change when the dual extruders are mounted.

Received my LMU’s and hardened steel bars from china 2 days ago, 1 week shipping, no duty yay.
Totally impressed with the results, backlash is gone (that was expected). Printer is back to acceleration 1200. Now progressively improving other axis, I had ordered enough to install linear ball bearings / guides on the whole printer.

How does the noise level compare to the igus bearings?

almost silent, as oscillations stopped. A little bit of tic-tac from the ball bearings but that will go away once I’ve lubricated the shafts. The guides are lubricated but I’ll add a tiny bit of pure vaseline oil like on my other CNC.

Hi erv, can you detail what and where you ordered from? I’d like to update my AO101 with this mod. Thanks.

I’ve ordered steel bars and LMU10 bearings from this ebay seller