Tired of seeing bulges and ribs on the walls of your 3D printed model? In this post, we’ll explain how to fix Z banding and Z wobbling, which is the usual culprit for these issues.
Ribbing or Z banding is one of many common issues to plague 3D printers. It tends to make layer lines even more visible than they already are, so it can completely ruin the aesthetic of your 3D printed model. Banding is not quite as common as stringing, rining, and other problems, but the fixes are relatively straightforward.
As with most 3D printing problems, Z banding and Z wobble have multiple fixes, so it will be up to you to figure out which solution to try first.
With that said, let’s get into it.
What causes Z banding?
Z banding is usually the result of one of two factors: Z wobble or inconsistent extrusion. Frustratingly, Z wobble and inconsistent extrusion are problems of their own, which can cause even more issues.
The flip side is that if you can fix these two issues, you’ll notice a really marked improvement in your print quality right away!
What is Z wobble?
When I first started 3d printing, I thought Z wobble and Z banding were the same thing. They’re not, though they’re related.
Z wobble happens when your 3D printer does not move in a straight line on the Z axis. It refers to the actual misalignment of the printer head.
This is probably because your Z-axis rod or lead screw is slightly bent or crooked.
Due to the Z axis wobble you’ll end up with misaligned layers in the X-Y (usually the “flat”) plane. That causes a layer to get pushed out of alignment and create a small band – that band is what “Z Banding” refers to.
In other words, Z wobble produces Z banding.
Here’s what’s happening:
As the lead screw turns and moves the print head up, the print head will end up in a slightly different left-right position as the lead screw rotates in different directions.
In short, the crookedness of the lead screw translates into the print head moving left to right.
Because the lead screw makes full 360 degree turns, one side of the screw will produce a shift, and the other side of the screw will produce a properly-positioned print head.
The result is Z banding lines.
Lead screws are the usual culprits for Z wobble, though it can also be caused by a slightly bent stepper motor shaft, or a loose coupler somewhere.
What is inconsistent extrusion?
Inconsistent extrusion is when the same amount of filament does not flow out. At one point, there may be less filament flowing out, and at another point, there may be more.
This is usually caused by a clog somewhere in the nozzle or an issue with the temperature regulation.
A fully clogged nozzle will prevent any filament from flowing at all, so if the nozzle is indeed responsible, there’s probably a small buildup of material in it that is preventing the filament from flowing as it should.
How to tell whether Z wobble or inconsistent extrusion is causing your Z banding
A crooked lead screw will produce very regular banding: you should be able to count the number of layers between bands to a degree of consistency.
Inconsistent extrusion produces more random and (inconsistent) Z bands.
Of course, it could still be both, so if you find that after fixing one factor the problem remains, you will probably want to fix the other issue too.
How to fix Z banding
As you have seen by now, fixing Z banding actually involves fixing Z wobble and inconsistent extrusion. You have a bonus of fixing three problems for two!
We’ll talk about a total of 5 solutions: three for Z wobble and two for inconsistent extrusion. Hopefully, one (or more) out of five will fix the problem for you.
Fix Z wobble by tightening the stepper motor
The first and easiest solution to try is to make sure your stepper motor is correctly seated and is not sending any unwanted movement to your print head.
Place your hand on the Z motor, and give your printer a command to move 40 mm up, and then immediately 40 mm down. You’ll have to do this by using G-Code and pushing it from the computer. You can also use Octoprint if you have it set up.
As the motor moves, and especially during direction change, if you feel any jolts or fhits, you’ll need to tighten the stepper motor. Find the bolts that secure the motor to the frame and tighten them down a little.
Alternatively, you can print a stronger bracket for your Z motor and use that.
If the banding issue is bad, you first bracket will not be aesthetically pleasing, so just fix the printer with the first bracket, and if it really bugs you, print a better one and replace it!
A search on Thingiverse will bring up plenty of mounts for your printer if it’s popular enough. You can also adapt another printer’s mount to your own.
Make sure the rod coupler is tight
A cylindrical piece connects your motor to the lead screw. This is called the rod coupler, and it should be straight. If this is crooked, your Z axis movements will be crooked as well.
To fix it, just remove the coupler by loosening the two bolts, detach the coupler from the stepper motor and lead screw, and attach everything together again, making sure it’s all straight and secure.
Check the lead screw
If the stepper motor is firmly seated and the coupler is straight, the problem is probably your lead screw. Most 3D printers rely on lead screws to move the Z axis up and down.
To check if the lead screw is straight, remove it from the 3D printer, place it on a flat surface, and try to roll it. If it does not roll smoothly, something is wrong.
Lead screws and threaded rods are quite solid, so trying to bend it back into shape will be quite difficult. It’s a lot easier to buy a new lead screw. They’re fairly common and easily available at hardware stores or online.
If the screw is only slightly bent, there are certain 3D printed mods you can use that utilize a bearing to compensate for any unwanted movement the bend is causing.
This should fix any problems you’re facing.
In fact, you should use the bearing part even if your lead screw is straight, as it gives you a greater degree of precision on the positioning of the rod.
How to fix inconsistent extrusion
Inconsistent extrusion is a fairly common problem, so the solutions below will help you in the long run as well.
Clean the nozzle
The first thing you should try is to just clean your nozzle. There are two ways to clean your nozzle, depending on the scale of the buildup:
Use a nozzle cleaning needle
Pick up a nozzle cleaning needle, which is a thin piece of metal that you can insert into the nozzle to break up any residue. To do this, heat up your nozzle to the highest it can safely go(if you have a Bowden setup, this is 230 degrees C, for all-metal hot ends, you can go up to 260-280 as well).
Next, raise the toolhead until you have enough space to comfortably get underneath it.
Then, insert the cleaning needle into the nozzle and move it around. Do this a few times to break up as much residue as possible. After a couple of attempts, extrude some filament. As the filament flows, it should push out the residue as well.
Do a cold pull
The next thing you can try is a cold pull. To do a cold pull, first remove the Bowden tube from the hot end if you have a Bowden extruder.
Then, raise the temperature of your nozzle to just below the melting temperature of your filament.
Push some filament through the hot end until you feel it give a little, and immediately decrease the temperature by a few degrees. This will help the filament cool a little.
Finally, yank the filament out: this will pull the filament as well as the residue out.
You may need to do this a couple of times.
Burn the filament out
The most extreme solution to try is to unscrew the nozzle from the hot end and use a blowtorch to actually burn the filament out of the nozzle.
Please be careful when doing this: you can severely burn yourself, and the brass nozzle can deform if it gets too hot.
Replace the nozzle
Some types of residue may be too stubborn to remove, so in that case, you may just have to throw away your old nozzle and use a new one instead.
Related: Ender 3 nozzle sizes
Calibrate your extruder
In case your nozzle is clean but you’re still getting inconsistent extrusion, you’ll have to calibrate your extruder. Calibrating your extruder is a fairly simple process which you can find below:
Can you fix already-printed parts?
In case you have some already-printed parts lying around, what can you do to fix Z-banding that’s already present? Some basic post-processing can help to reduce the unsightly bands on your print.
Here are some things you can try:
- Sand the walls of the print to reduce banding
- Use layer smoothing solutions
- Paint over the walls of your print
Conclusion
Z banding and Z wobbling are issues that often plague 3D prints but have a whole host of solutions you can try in order to fix the problem.
The bonus is that you can end up fixing a lot more problems in one go when you resolve this issue!
