Ok, so I ordered the Kittaz, put it together, and printed a calibration cube. I love it, it worked great. However, when i go to print a circle, or round objects in general, I get problems with the shape. I have looked for answers online, I’ve calibrated the x-axis, y-axis, and z-axis steps. The surface is leveled, the extrusion steps are calibrated. I have no idea what’s going on, which leads me to believe it could be a software issue? I am using Slic3r and pronterface. Also, when i turn the speed down in slic3r, it doesn’t seem to change the print speed. Any help would be greatly appreciated.

ConnectorFront.stl (541 KB)
Fine.ini (3.13 KB)
ConnectorFront.gcode (4.67 MB)

middlemiddle.stl (331 KB)

I’m experiencing this same issue on my new KITTAZ. It is due to backlash resulting from very sloppy linear bearings (the Igus bearings) on my machine. The fit of these is really poor - I can measure .5mm of slop in them with a feeler. I have ordered hardened 10mm rods and ball bearing linear bearings from some eBay vendors I’ve used in the past. This will eliminate the slop and backlash.

There are other contributors to backlash too that you should check:

  1. make sure the belts are tight (but not too tight)
  2. make sure the pulleys on the stepper motors are secure (the set/grub screws)
  3. test the Y axis by grabbing the front corners and pushing (gently) side-to-side. If you feel any movement, you should start by adjusting the linear guides as per the build manual. I was not able to remove the slop completely without causing binding.
  4. test the X axis by grabbing the left and right and checking for slop. See 3 for fix.
  5. may as well check Z while you are at it - first the left then the right side.

I just replaced my Taz 2.1 x axis rods with hardened rods and bearings… Sooooo much better. I look forward to replacing the Y and Z hardware later this year.

I hope Lulzbot moves away from Igus bushings with the next generation of Taz.

If you rotate the part 45 degrees and reprint it, will the misalignment in the circles follow the rotation?

There’s been numerous posts here about misaligned circles. Almost all appear to have turned out to be belt/belt tightness related.

If replacing the bushings with linear bearings, is it also necessary to replace the rods with hardened steel? Aren’t the TAZ rods already hardened steel?

Has anyone attempted an upgrade of the TAZ with a linear rail system? It would take a lot of re-engineering, but it would virtually eliminate any backlash or slop issues in the motion system.

I have found an excellent way to take the slop out of my Y axis at least. First I measure the distance between the ends of the rods and make sure they are exactly 5 7/8 inches center to center. I have made a jig to hold them exactly that far apart. I then loosen the 4 bushing mounts on the table and rotate them so they are snug against the rods, removing the slop. I rotate the left rear and right front clockwise, and the right rear and left front counterclockwise. I then check the bed for smooth motion from end to end. This has virtually eliminated any slop in my Y axis and greatly improved my print quality.

My understanding is the stock rods are not hardened and that would make sense with the plastic guides.

I am installing bearing guides and hardened rails even as I type this! Ultimately though, I intend to make my KITTAZ double wide - 24" on the X axis - and convert to linear rails on at least the X and Y. But that is a few months away. Frankly, the guide rails with ball bearings is going to eliminate slop and backlash well beyond the requirements for the 12" TAZ. I think I’ll need more rigidity than rods can provide for a 24" long X axis.


May I ask you who your source is for the hardened rods and linear bearings? I am currently in the planning for upgrading my TAZ likewise, but have not yet sourced the rods, as I was under the impression I didn’t need them. I have purchased my bearings from Easy RepRap as theirs were well reviewed.

I normally buy from Misumi but since I know this is temporary for RazMaTAZZ, I decided to use Chinese stuff from ebay.
I got 11 of these:
and 6 of these:

But it turns out that 19" is too short for the Y axis so I am using the stock today (just installed them today) and will replace with 500mm rods.

Search for x axis backlash it was OPed by erv. The stock rods are not hardened and I threw up links for the Misumi parts. I still suggest going threw eBay like mhackney suggested. I just know for sure that the Misumi parts all fit and work and cost me ~$120 with shipping. If I were to do it over I would probably go with mhackney’s suggestion of using v-rails and slides to make the x axis more rigid, but the double shaft setup works fine.

Thanks on the stock rod info.

So the rods I ordered (hardened) are quite nice but they are 19" long, not 500mm. They work perfectly for X and Z but are about 4 mm too short for Y. I used the stock rods temporarily on Y while I figure out what to do. This was purely my fault, I knew they were a bit short and didn’t really measure the Y length very well. There are vendors on eBay who have 500mm rods too, use them. My options are to either buy some 500mm rods or to make little rod mount extenders for one end of the Y axis. I’m just going to use the non-hardened rods for a few months while I work on other projects and prepare to convert RazzMaTAZZ into a double wide (24") printer with rails.

Why not just reprint the Y axis mounting hardware extended and adequately braced to adapt your 19 inch rods? Seems like you could cover the 4mm deficit fairly easily. Not much of a sacrifice to your print area.

Yes, that is basically what I mean. But it could actually be a bit easier with just printing a collar. It is a minor issue but not worth dealing with right now.