linear bearing backlash, big X axis issues

Hi erv, thanks for documenting this so well. i’m considering doing the same to my TAZ since I have similar quality issues and also see the same amount of backlash. but I wanted to ask if you had a gcode file you’d be willing to share that exhibits the problem…?

no specific g code, pretty much everything that has curves in it. Single motions on X or Y are ok most of the time, but when you combine them, you get oscillation and backlash appears.
That’s basically the same conclusion in the latest Make issue. Still, the TAz remains a very good printer and is easy to upgrade to get rid of those problems, for little money. I had to go the same route with my UM1 at work

Yes, when I read the make review I had a similar reaction. I really like to have ‘before’ and ‘after’ reference prints to make sure that my upgrades are solving the problem. I’ll start with the make models and maybe add a few if I need them.

Can I ask why you got rods too? Are the stock ones too elastic or do you just want a matched set with the bearings?

The stock rods are not hard enough to run steel bearings. They form grooves. I tried it on my Y axis but went back to polymer bearings due to the rods wearing.

I started noticing exactly the same issues as described in the OP’s video, and I also have that amount, or even a bit more slack in my X axis now!

Also don’t know how it came about , I have only had the printer for like 2 months and have printed maybe 100 hours tops on it.

Anyway, I ordered replacement bushings and will try to replace them and see if they really do wear out so quickly.

So would everyone recommend that I also switch to bronze bushings instead? I will also check the Y axis for play in that case, since they use the same bushes

that will not solve your problem, at least not durably. Igus bushing could be ok if they were installed in a compressing housing as they are slightly oversized. Compression allows to have them fit the rod at a tighter tolerance.
However, the bushing on the printing head (and elsewhere) are open for most of them and do not compress the polymer bushing hence backlash.

Using the ball bearing linear guides and tougher steel rods solved the problem for me.

Alright thanks , taking it apart I noticed replacing the steel rods is not a big deal so I guess I’ll go down that route as well in the end.

Right now, my sloppyness in the head is gone by just replacing with new IGUS bushings (i had them around anyway)

There is still a slight slop but I guess that comes from factory.

Honestly I would suggest Lulzbot to adress this in future TAZ’s because that is something that wears out far too quick on an otherwise perfectly solid machine. It’s not like I put 400 hours+ of printing in

On a unrelated note - since replacing the bushings I now have a disgusting loud grinding noise when Homing Z axis?? I only changed the bushings on the X axis , no idea how I managed to create that. It sounds like the Z axis threaded rods are producing this sound when retracing the head all the way down near the print bed… sounds like it’s coming out of the stepper motors for the Z axis

Any ideas? when I raise Z higher the noise goes away and the head runs up smoothly no problems

Do you have the part #'s for the bars and bearings on this guy’s website?

The Misumi Part #'s are:



thanks so much, ordering this as well to give it a shot!

I’ve got the same issue. The bearings were so sloppy I could easily twist the x carriage. I think is it just a poor choice of components. As for the noise, see this post - it is NOT unrelated. Seems like a common issue. I think someone must know the secret to setting up the x rods, because as soon as I took mine out, I could not get them back together without the zaxis grinding and seizing. A whole lot of playing has got it to run mostly without noise and stopping.

I have replaced the IGUS with different bearings. We’ll see how they perform long term. I’ve only had the printer a few weeks, and not a lot of hours on it - maybe 30 - and those IGUS bearings were loose. They were probably that way the whole time - I probably just noticed after 30 hours of running. All the other axis are also loose as well. Its a systemic problem.

thanks for the hint, hope I can get the Z axis back to how smoothly it originally operated…

As for the IGUS bearings - even with brand new ones you are right that there is a slight bit of slop. Before they were worn out however it did not feel like the slight slop was causing problems with print quality though. I also noticed the slop quite early after purchasing the printer but kept using it until the prints started getting worse.

for the record i replaced my X axis IGUS bearings, no more Slop in the X axis. But still having some print Quality issues, so I’ll analyze further…

igus replacement solved a lot of things. Along with printing parameter adjustements. Finally reduced the acceleration anyway, and printing a 50 mm/s now, all perfect

See my other post for Z axis solution…

I have similar issues with my ao-101… the x-axis bushings are loose.

Would you recommend swapping to linear bearings and 10mm rods ?

Or if I just want a stock replacement, what should I get? It’s so confusing … I’m not sure lulzbot sells a direct replacement for the AO-101.

I doubt the TAZ and the AO-101 are using the same bushings.

if you’re gonna replace the rods, use hardened rods.

I replaced them with the stock ones for now, and am back to printing however I am Aware These will wear out again in the next 2-3 months so I will order the harder bearings and rods since I don’t want to do that every time,.

dunno about the AO101, if the parts are the same. :frowning:
but I am a car Enthusiast and there I always say better replace a worn out part with a stronger one instead of doing the same repair various times. :wink:

they will wear instantly with the tight tolerance, and marking will quickly aggravate the noise. Get the hardened rods

Anyone know if I can try just replacing the stock x-axis rods w/ the PSFU10-500 hardened rods w/ out also replacing the bushings? Will the PSFU10-500 rods play nice w/ the stock IGUS bushings?

…also Misumi said there is a g6 (part # psfj) and h5 (part # psfu) tolerance for the linear shaft ([20-800%2F1]&PNSearch=PSFU10-500&CategorySpec=00000028943%3A%3A500).

Which one are people using?