TAZ 4 left & right Z motors get out of sync

General LulzBot TAZ
1

So this past week it’s happened to me twice that the left and right Z axis motors will get out of sync. The first time it happened I was near the machine and it did it when homing the Z axis after a 80mm tall print, part way down I heard a ratcheting sound and it stopped. Nothing collided, there was nothing in the way and the nozzle was still a good 10mm or more away from the heated bed.

I did not think much of it just thought it was a fluke. I leveled it all back up again and printed another dozen or more prints then tonight I left the room during a print (Rocktopus) and came back to about 1/4 of the print done and the rest in a ball around the extruder. I used software to try and move the Z axis but it was stuck so I measured the distance of the extruder rods to the aluminum bed and it was off by 14mm so one of the motors slipped again.

I keep the drive and smooth rods clean and I keep lubriplate (lithium grease) on the screw rod. So, I have never opened the control box on my printer, is this current thing that I can adjust? And if so where can I find some instructions on proper adjustment. Or is one of my motors drying?

I rely on this printer almost daily so I would appreciate any help.

2

I just took my whole x/z axis apart because of that noise and actual binding of the z axis.

It looks to me like there is an issue with the alignment of the carriages on the z axis. Specifically, the hole centerlines from left to right of the xaxis rods. When you push on the z carriages at the back where the x rods are, the carriage will want to twist and bind up on the leadscrew. It looks like the plastic right by the leadscrewnut touches the leadscrew and causes the binding.

As far as I can tell, the construction of everything seems to influence this. Since nothing is square, I get good motion on part of the z stroke, but not others. I think their trick is to assemble the entire machine somewhat loose…

The telltale sign was pulling the xrods out of the left side plastic holder. The rods want to be about 1/2" further back than the hole they are being shoved into. When you shove it all together, that tweaks the zcarriages and will cause the binding on the leadscrew.

I have pulled the frame diagonally and tightened the bolts back down. I have loosened the screws and pushed the leadnut over in the plastic to give clearance to the leadscrew. I have loosened and moved both the xbearing and the xmotor mount as far to one side as I could (opposite ways). You can do this by removing the 4 bolts on the aluminum bracket to get to the 3rd screw hidden behind the frame (nice). This still does not get the left/right holes to be on center, but it helped a lot. I think the design is just wrong, with the holes in the wrong place.

Next, you will have to play with the set screws on the xshafts, and the tension on the x belt. I was tempted to leave one side loose, but the belt tension would not like that. Pry the carriages apart or together, then tighten the set screws and tension the belt. Then see what happens. It will bind, of course, so iterate several times until you get it the best you can. Make sure the left/right carriages are level, without one higher than the other (normal calibration step…).

I hope that helps. The real fix does not look too easy. Either move the location of the zxaxis assembly on one of the sides (which means new motor bracket and upper bearing bracket - which can be printed, minus the brass heat inserts…) or redesign the aluminum plate on one side to move the one of the xrod mounts. I guess you could slot the aluminum - but that means the bolt holes and the rod holes. :frowning:

That was a good 4 hours, so be prepared…

Well, looking at it again, I see everything “Should” line up (per the design), but doesn’t in real life. So there must be an issue with the hole perpendicularity thru the xbearing block/x motor block. I could open them up, but I think that would be a bad idea. I think I may be able to SHIM one side to angle the rods back to centerline. I’ll give that a try next. That may be the way to go…

Anyone else having this issue???

3

Yes! I am having a similar issue. I have the KITTAZ, which is just Taz in kit form. The kit didn’t come with a handy squaring tool as the online support instructions use, so I had to just do the best I could. I was getting that nasty vibration noise as the the Z-axis traveled through the middle of its screws. So I printed a little 4x4" square, sanded it more square then realigned the frame–it was off for sure. Now it is binding at the bottom of the z-axis stroke, in the bottom 1" above the bed. It is binding so bad now that when I home Z, the left side screw binds and stops moving. Since the Z stop is on that side, the right side Z motor keeps on going down and pushes on the bed until I can jump up and slap the power switch off!

I will re-read your post and evaluate my machine again.

I would love it if Lulzbot wrote a step-by-step “how to realign your frame” manual that would solve this issue.

4

OK, just saw that when I reinstalled the big electronics box that I didn’t push it all the way down. One of the heads of the M4 bolts on the X-axis is touching the bolt that holds the rear mounting bracket for the electronics box. I think I just need to loosen the box and slide it all the way down. User error.

I would still like to see a frame squaring manual from Lulz though–could have saved me some time. Or they could have included all those little jigs and spacers that are pictured in the assembly instructions.

5

Assembly instructions? Mine came assembled. I guess I need to hunt those down.
Yeah, mine was freezing at the exact same place - right above the z limit switch…

6

I have also been having this issue with my Kittaz. So far it has been my worst 3d printer purchase due to all of these issues and component choices. The Z axis will occasionally refuse to lift when the print has finished a layer - this results in squashed prints that are too short. Loosening the X belt tension helped a little bit, but as another poster stated previously, the holes in the X idlers do not allow the rods to fit where they would like to and this results in even more stress on the Z axis (lead screws). I am still in the process of tweaking to hopefully get it working the way it should and will be printing these: http://www.thingiverse.com/thing:436981 to see if it helps with the issue at all.

7

Cool! Let me know if they work…I’ll print them up too! :smiley:

8

I printed out and installed the X ends. Here is what it looks like attached to the taz:

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It fits together much more nicely than the stock solution because the whole assembly is one piece. In my brief testing I didn’t get any grinding when raising the z axis up and down several times. It’s printing out a 155mm leadscrew now, so i’ll see if the problem really is resolved. I still had to keep the x belt tension fairly loose, otherwise the z axis did grind, so obviously this isnt a fix all solution. I used heatset nuts, but one ended up worming its way out which is why you see the nut on the top right corner.

9

I’m having issues as well now.

Bought the printer assembled and all was perfect until i started having print quality issues and noticed the X-axis IGUS bearings were very loose and worn out.

After replacing them, which of course meant removing the X-axis smoothrods from the holes, I also noticed the smoothrods looked kind of like they doesn’t line up with the holes perfectly. I just put it back together, pushing the X-axis rods in as they were.

Now the Z axis makes grinding noises when homing. :frowning:

I have not attempted to do all the things described in this thread - because I wonder, can’t Lulzbot comment on how these things are assembled, maybe the do it laying on the side or something to remove tension on the various parts before tightening all the screws. Probably you are not supposed to just remove the smoothrods on the X axis just like that… no idea.

Anyway I’d like to get this sorted without hours of trial and error on my side…

10

If the binding has just started after swapping out the Igus bearings for the X axis, it is going to be the reinstalling of the smooth rods. Your leadscrew is going to act like a fulcrum between the vertical smooth Z rod, and the horizontal X axis smooth rods. If X axis idler or motor mount (depending on which side is binding) is too close to the center or too far out, it will place added pressure on the smooth rod and leadscrew.

Loosen the set screws on horizontal smooth rods, so you can move printed piece closer to the center, or further out. With your stepper motors disabled, you will be able to turn the lead screw by hand to find the optimal positioning. Try to find the sweet spot, that creates the least resistance.

11

OK, let’s see if I can get thru this without losing the attachments…

So after a lot of playing around, I have had to SHIM the backside of the leadnut mount part (for lack of a better name). I did it on both sides of the machine. The two rear screws each got 2 washers, and the 2 front ones each got 1 washer. This helped a lot in getting the aluminum plates square to the frame and each other.

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That didn’t quite get the top rod to line up side-to-side for some reason, so I got out a drill bit and took just a hair off the hole - you can see the scraps, not much was removed. But that really, really helped a lot.
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Then I tightened everything up - AND IT WAS BOUND UP AGAIN!!! :smiling_imp:

So more investigating, and I see that the leadnut mount part IS NOT FLAT on the leadnut!!! Off by 16 mils (feeler gage shown)!!!

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So, what to do? I pulled one washer out from behind the front top screw that I just shimmed in (so now no washer), and took 1 of the 2 washers out from the rear top screw - so effectively putting a twist into the leadnut mount part with respect to the aluminum plate. Now the leadnut sits mostly flat. So I tightened up the 3 M5’s and…I could still bind up the leadnut - but it took some doing. So I loosened up the 3 screws - and it works perfectly! I would post a picture, but it looks like 6 is the site limit :unamused:

So, moral of the story - it’s those 3 M5 screws that are torquing the leadnut and causing all the grief. I am able to leave 1 tight and 2 loose, and no grinding, and free moving axis.

Now I have to figure out why I have Z Banding - surely related to all this mess.

Good luck all - hope that helps.

12

Early on I had a noise coming from the left side and called Lulzbot, they talked me through taking out those screws on the leadnut (as you called it) and then moving the Z axis up and down then putting the screws back on but when I would tighten them it still made the noise and I was directed to just leave the screws a little loose.

I was not sure this was related to the original post issue or not.

13

wow thanks for that.

I only loosened and retightened the 4 screws on the Z axis assembly, wigglet the assembly up and down a few times and retightened (not too tight). That already fixed my grinding noise coming from the left Z axis rods.

awesome!

14

I am having this same issue with my pre assembled Taz 4. I have been printing with it for a couple weeks now. Just today, I went to start a print and as it homed all axis, the z axis stopped 6" from the bed. X and y axis move fine in all direction and the z will move up but when I manually move it back down, it stops at the same 6" above. Matterhackers walked me through all they could think of but we couldn’t get it to go down. When we looked at the code, it said the x y z axis were all at 0. The printer thinks the z axis is in the home position at 6" off the bed. That’s why it won’t go down. What are my options?

15

Just wanted to bump this post up as it’s still an issue. My machine made a bit of noise homing last night and the Z motors were again out of alignment.

16

Anytime you have intermittent z movement, or one side of the Z axis getting out of sync or it appears higher or lower than the other you’ll want to make sure that the Z axis is:

  • Level the z axis in relation to the Y axis metal bed plate
  • Lubed- We use Lucas #2 white lithium grease. The TAZ4+ has a much tighter Z axis drive system. The more friction it has the greater of a potential Z axis binding you may encounter.
  • rarer, but it has happened once or twice- Make sure the fan in the electronics enclosure is spinning.
17

I do re level the z axis to the aluminum bed each time.

I use Lubriplate white lithium grease (very high quality).

My fan over the electronics does work. It changes speed during printing but I am assuming it’s being controlled to do so.

18

I can’t believe it! ‘Rarer still’ happened. I had tuned the frame sideways to work on the Taz 4/5 and then when I was printing vase mode where the Z axis is constantly turning, the left Z motor was making a thumping sound. Just for the hell of it I poped the control box cover and the fan was hitting a sense wire. Moved it put the cover back on and the Z motor noise stopped!?
Amazing. I would have never thought that would have anything to do with it.
Thanks, Orias!

19

Glad you found it!