11
$\begingroup$

I have an Ender 3 that I have been pretty happy with so far, however it recently started an odd behavior and I can't figure out what's causing it.

What happens is that the first ~3 mm of the print comes out "sloppy". After that, everything clears up and it prints fine for the rest of the print. (Although it perhaps looks a little under extruded on the top layer)

enter image description here

It looks almost like it's over extruding. But if that's the case, why would it only be for the first 3 mm? Then the top layer looking under extruded makes that possibility even more unlikely.

This is consistently happening regardless of what I am printing, the brand of filament (I only print PLA), or the bed temp or hot end temp. I've tried tweaking with the bed leveling and giving a little more gap on the first layer, but that doesn't seem to change anything either. I also calibrated the extrusion multiplier and it's spot on now.

I use Ultimaker Cura 3.6 as my slicer. I tried resetting back to defaults to see if maybe I had inadvertently changed something but that didn't help either.

I have done a few upgrades - Marlin firmware, Capricorn tubing, glass bed, replaced the (broken) plastic extruder with one of the metal ones, new PTFE fittings. I didn't notice the problem until recently so I can't say if it started corresponding with any of those upgrades.

When I first got it, the prints came out beautifully from the first layer, so this is really frustrating me. I'd like to get it back the way it was.

Any suggestions on where to look?

Update: I did some slightly more controlled experimemts and I did get it looking a little better. It does seem related mostly to bed tempurature. The cooler I make the bed, the better it looks. However as it gets cooler, the prints are also starting to warp and break loose, so the print ends up failing completely. I had a hard time getting a successful print below about 45 degrees, and even at that temperature it still isn't completely clean. I'm using glue stick for adhesion and it just doesn't seem able to hold it without some heat. I traditionally have run around 50 degrees before this problem started though, so it seems odd I have to drop below that now.

Also, for more info, the cube dimensions are pretty close in the X and Y, but were about .5mm short in the Z. So the layers do seem to be settling.

I did check the bed temp with a non-contact thermometer and it was consistent with what the printer reported, so it doesnt seem to be a bad thermostat throwing things off.

$\endgroup$
3
  • $\begingroup$ what's your temperature settings? $\endgroup$ – Trish Jan 20 '19 at 20:28
  • $\begingroup$ I've tried several. Bed from 40-60. Nozzle from 195-220. $\endgroup$ – Steve In CO Jan 21 '19 at 0:46
  • $\begingroup$ I've had similar prints with too small nozzle to bed distances, increase the distance by e.g. leveling with thicker paper or use an offset for Z. $\endgroup$ – 0scar May 12 '20 at 21:54

10 Answers 10

11
$\begingroup$

After much trial and error, I think I finally figured out the solution.

Even though I could get better prints by tweaking with the temperatures, I could never totally eliminate the problem. The better I made it look by cooling down the bed, the more likely it would break free and the print would fail completely.

At one point though I happened to print something taller, and interestingly enough a similar band of ugly layers appeared higher up in the print as well.

So I started a closer inspection of the Z axis rollers. The Ender 3 has a funky setup where there are 3 rollers at each end of the X axis. Two are fixed and one can be adjusted to change the tension of the rollers against the Z rails. What I discovered was that a couple of the non-adjustable rollers weren't terribly tight and could be turned by fairly easily with my fingers. At the same time, the adjustable rollers are starting to wear a groove.

On a hunch, I decided to try re-adjusting the tension so that I could no longer turn any of them with my fingers. It definitely had an effect...now the bed was too high and it would no longer extrude the first layer because the nozzle was too close. This required going through the complete bed leveling process to get it back in spec.

Once I got it re-leveled, low and behold it's printing like new! The height is coming out spot-on too.

Measuring the calibration cube

I suspect what was happening is that the rollers were too loose and at certain heights they we allowing movement in the Z axis. Perhaps there is a flat spot that was allowing the X rail to droop, then once it got past the flat spot it would print cleanly again.

I haven't printed anything tall enough yet to see if the bad layers still show up higher in the print, if they do, I think it is probably a sign that I need to replace some rollers. In the mean time, I'm thrilled to be getting decent prints again!

Update: This ended up NOT being the solution to my problem. However it does seem to be related. As I mentioned in the comments, the problem returned after a few days of the printer sitting unused. I have since been able to get it printing better by going the opposite route - loosening up the Z axis bearings. At the moment it is printing somewhat better, but still not perfect. I am also having under extrusion issues when may or may not be related. I have ordered some new rollers to see if that helps since some of them had a pretty good groove worn in them.

Another Update: I replaced several of the Z rollers that had become grooved with some that claimed to be a little harder material. So far this seems to have mostly cleared up the issue. I have now completed several large print jobs and the first layers have been coming out pretty good.

I also ended up taking out the Capricorn tubing on the extruder. The extruder skips were becoming quite bad and causing under extrusion issues throughout the print. The Capricorn has a little smaller inside diameter than the stock tubing and I wondered if it was too tight on some filaments. I went back to some plain white cheap PTFE and that problem mostly went away as well. I still hear the "click" once in a while, but it is fairly rare. I may try tweaking the motor current a little to see if I can get rid of that. All in all though, the printer seems to be printing about as good as it ever has.

$\endgroup$
9
  • 1
    $\begingroup$ did you ever get yours fixed permanently? $\endgroup$ – rmawatson Jun 6 '19 at 15:36
  • 1
    $\begingroup$ I just experienced a similar problem after taking things apart to fix an unrelated issue, and it turned out the Z lead screw clamp was not tight on the screw, allowing it to slip. Overtightened eccentric nuts were probably also involved. $\endgroup$ – R.. GitHub STOP HELPING ICE Jun 6 '19 at 16:59
  • 1
    $\begingroup$ Yes, I haven't had a noticeable problem in quite a while. The things that seemed to have the most effect were replacing the rollers with the harder ones and also installing an anti-backlash nut on the Z lead screw. Of course getting the tension just right with the eccentrics is important as well. $\endgroup$ – Steve In CO Jun 6 '19 at 17:03
  • 1
    $\begingroup$ Actually, my problem ended up continually coming back, was a lot like OP's, and was frustrating to track down. Eventually, I re-aligned the Z rollers and (this is probably the most important part) loosened the screws holding the Z lead screw nut to the carriage, which I'd tightened after unnecessarily removing it. They should be backed off at least a quarter to half turn from fully tight. $\endgroup$ – R.. GitHub STOP HELPING ICE Jun 8 '19 at 19:18
  • 1
    $\begingroup$ Follow up a year later: the problem still has not returned after replacing the rollers and adding the anti-backlash nut. Really this little printer amazes me sometimes at how beautifully it prints for a $200 (+ a few mods) printer. $\endgroup$ – Steve In CO Apr 9 '20 at 3:31
6
$\begingroup$

I had the exact same problem as you. And after trying all of your ideas (Thanks so much for the amound of information!!!), I discovered that in my case, the problem was actually the printer skipping a step every other layer (at the beginning), which lead to the exact same thing, the bottom layers being "compressed", leading to a lower height in general (and overextrusion at the bottom). In my case the solution was to tighten the screws that hold the Z-Motor in place (as well as printing a spacer for the motor, so that the axis-screw (no idea how that thing is called) wouldn't bend: https://www.thingiverse.com/thing:2925230) as the Z-Motor would push itself down and lift itself up every other step, resulting in a loss of a layer.

$\endgroup$
1
  • 1
    $\begingroup$ Has this problem come back or is your solution still working ? $\endgroup$ – rmawatson Jun 6 '19 at 15:38
2
$\begingroup$

I had trouble with the first few layers looking like over extruding (they were just compressed). Turns out the X axis was loose. On zeroing for a new print the arm would be sloped like this |/| as the Z axis lifted it would slowly end up |\| over the duration of the print.

$\endgroup$
2
$\begingroup$

I had this problem as well, the problem is not too much give on the Z axis, it's that there is not enough give, so loosen the Z-axis wheels on both sides till you can freely move one of the wheels with your hands.

This solved it for me.

$\endgroup$
1
$\begingroup$

It looks like you need to calibrate your Z0 by adjusting your endstop height. It's starting too low.

I think you are printing your first layer too low, and underextruding to compensate. Do the paper test with your Z at 0, confirm it's good. Do the 100 mm extrude test and confirm it's pulling in exactly 100 mm. Measure your filament diameter in several places and make sure the slicer value matches.

$\endgroup$
1
  • 4
    $\begingroup$ Can you elaborate? I don't see how the end stop height would affect anything as long as the bed is properly leveled. My skirts come out a nice even .2mm +/- .05mm all the way around so it seems to be set right. $\endgroup$ – Steve In CO Jan 22 '19 at 4:50
1
$\begingroup$

Same problem with my Ender 3, although not as severe as the OP, its about 0.5 mm over the first 1 mm that is lost.

After checking my motor as suggested, it was solid. However as with the OP, one of my adjustable wheels was loose on the Z axis, and could be turned by hand. Tightening the eccentric wheels on both sides to remove any slop has resolved the issue. Multiple test cubes have come out perfectly.

$\endgroup$
3
  • 2
    $\begingroup$ Good morning, and welcome to the 3D Printing SE site. I see from your profile that although you are new to this site, you are familiar with the StackExchange structure. On this site, your answer might be better presented as a comment on the question, since it does not, in itself, provide an answer. $\endgroup$ – cmm Jun 6 '19 at 16:47
  • $\begingroup$ While the original post didn't really answer the question, the subsequent edits appear to have added a resolution. $\endgroup$ – Greenonline Jun 7 '19 at 11:14
  • $\begingroup$ Hmmm, I think that your last edit has removed some interesting information wrt to the 0.1 and 0.2. I think it was fine at edit #4.You might want to do a roll-back? $\endgroup$ – Greenonline Jun 7 '19 at 11:34
1
$\begingroup$

I solved the problem by adding a second Z-axis leadscrew. The problem was that I could have either too tight Z-axis rollers or a sagging gantry. Both of this lead to the nozzle rubbing over the print. In case of sagging, rubbing on the right hand side of the print and a too large distance on the left. In case of too tight rollers, rubbing on the whole print or on whichever side had the tight rollers.

If you don't want to invest in a dual leadscrew setup, turn the excentric nuts that fix the rollers of the gantry to the Z-axis; making sure that they are tight enough but not overtight.

$\endgroup$
0
$\begingroup$

I had similar problem with my Tevo Tarantula. Tried all the options mentioned above as well. It seemed to be Z-axis height related. Changed my Z-axis flexible coupling to a solid coupling which solved it for me.

$\endgroup$
0
$\begingroup$

I have this exact problem on the new , V2 Ender, and to be honest it’s becoming a pain. I also had, as many do the dreaded , fault of were the stepper motor does not sit square when tightened.

How this can be still a major problem seen by many is beyond me.that Creality cannot fix this yet is crazy.

Anyway I will also agree it’s definitely the rollers and the Z. Can I just ask, for me as well as many others I suspect, could you guys explain in a more noob friendly way. Such as which eccentric nut do you turn to loosen/tighten the Z axis? Also more for me really, how tight do we need it, real loose so it moves up and down very easy, or tight enough to have resistance?

Anyway hope you guys can help. Also the plastic shims didn’t work for me, still got the dreaded lift at the back. I cured that problem byw, with just a good old fashioned piece of cardboard stuffed behind it , it stopped the stepper sitting off the frame.

$\endgroup$
2
  • 1
    $\begingroup$ Hi and welcome to SE.3DP! Unfortunately, your answer does not answer the question. Without wishing to sound harsh, StackExchange is a Q&A site, and not a forum of threaded messages. The reason for this is to aid the search for answers to issues, and provide it in a structured Q&A way. I know that this might seem a pain, but can you re-post your question using the Ask Question link at the top of the page? When you re-post your new question, please feel free to refer back to this original question using the URL, seeing as it is the reason why you posted in the first place. $\endgroup$ – 0scar Mar 29 at 6:27
  • 1
    $\begingroup$ Hi Toz & welcome. As StackExchange is a Q&A site, you can't really have additional questions in an answer, as it will encourage others to answer your questions under the original question, and things will get messy really quickly. However, they are good questions to ask, so, please, could you edit your answer and strip out the questions, and post them as a new question, and refer back to this question's URL (so as to link the two).Thanks $\endgroup$ – Greenonline Mar 30 at 5:15
0
$\begingroup$

I too have a TEVO Tarantula Pro, two infact, the both did this out of the box (so to say). I think I just solved it for me. The comment above from Robet made me remember there was a small O-ring washer placed inside the flexi coupler when I built the printers.

The O-ring is the exact height of my first layer issues. I removed it and made sure that the motor shaft and the lead screw made hard contact. (Yes, I know thats not how they are meant to be, but all my previous printers are like that and they are fine). Even stretching the flexi coupler a few mm before clamping it to the lead screw.

And now my issue is completely fixed!

enter image description here enter image description here

$\endgroup$
0

Not the answer you're looking for? Browse other questions tagged or ask your own question.