Commonly called « Z Woobble » on most of reprap forums, this phenomenon is very frequent when you assemble a reprap 3D printer.
Often, this phenomenon can appear after a while whithout even knowing why or what we did.
There are always at least 1 or many reasons why this happens.
When we have this effect at the begining it can be time consuming or challenging to find out how to fix it.
What is Z Woobble?
A deposit 3d printer, is printing layers on top of the previous layers.
In a perfect world, all the layers are perfectly aligned and we have a perfect wall finish.
In reality, we can often have Z Wooble, it means that the layers are miss aligned and we have some « waves » on the sides of the prints.
If we look closely under light we can see a periodic pattern repeating itself.
If we look even closer we can see that the layers seems to be layered correctly but the height of each layer may vary slightly.
Le plastique s’écrase par moment et se détend à d’autres endroits.
If we place our threaded rod in front of a long print we can clearly see the pattern matching with the thread.
The identified causes so far are numerous, that’s why we can often accumulate them, making things challenging to fix.
Here are the causes we could identified so far:
Threaded rod are not parallel to themselves or to the guiding smooth rods.
The X belt tensioner is applying force on the Z axis smooth rods instead of the X axis smooth rods. THe smooth rods will then bend slightly enought to generate the issue.
The extruder is not calibrated. (EStep/mm not calibrated),The amount of plastic is too much or not enought making the plastic deposing irrugular.
The X carriage is not moving smoothly on the Z direction. One of the side is moving before the other side and the movement is not linear anymore.
One of the threaded rod is blocked when the axis is going down.(often when we are using auto bed leveling)
Auto bed leveling is compensating too much. meaning that one of the Z axis side is higher that the other side based on the heatbed. Use a flat object in order to adjust the height on both sides of the z axis to greatly diminish the compensation of auto bed leveling.
The filament is periodically blocked, impacting the plastic flow.
The extruder is sleepering on the filament. This impacts the plastic flow.
The layer height is too high or too low according to your nozzle diameter.
The filament diameter is not uniform and may vary a lot. Here again the plastic flow will be impacted.
One of the Z axis nuts have slack.
At least one of the nuts or the threaded rods are worn.In this case the best is to change both Threaded rods and Nuts on both sides.
The top of the threaded rod is constrained/ Threaded rods are never perfectly straight. constraining the top of the threaded rods will impact the guiding rods. Freeing the top of the threaded rods can fix the wooble effects.
Feel free to come back to us if you know some other causes and possible fixes.
You will have 2 symmetrical motor holders. One is for the right side, and the other one is the the left side.
Prepare M6x12 screws and their T-Nuts. Place them inside the 2 holes near the rounded corner of the part.
Take 4 M3x8mm screws and fix the motor and the support together.
Important Note: The motor support on the picture below is the Right motor support. The stepper motor with 1.2meter lead wire is to be screwed on this support.
In order to ease the assembly later on, make sure that the motor wires are places on the reinforced lateral side of the plastic part. It can also be placed on the same side as the M6X12 screws.
The wires are on the right for the right motor, and on the left for the left motor.
Place each motor at the base of the chassi so that the bottom of the motor is in contact with the chassis as shown on the picture.
Here it’s the right motor with the 1.2 lead wire.
This front view show the stepper motor in contact with the chassis. It will allow the stepper motor to increase it’s capacity to stay cool.
Also notice the M6 Screw location regarding the plastic part.
Now same thing for the left side of the chassis,with the motor wires on the left of it or behind, and the screws on the inside of the chassis.
Here is a view with both stepper motor in place.
This general view gives you another point of view of the assembly.
Preparation of side mounts
List of parts :
2 M8 threaded rods
2 5X8 couplers
[Provided] 1 small allen key
Take 1 threaded rod and a coupler.
The 5×8 coupler has 1 side the a hole of 5mm and the other side with a 8mm diameter hole.
This pictures shows the 5mm side of the coupler
Here the other 8mm side of the coupler.
Push the threaded rod inside the 8mm side of the coupler up to the end.
Do the same for the second threaded rod.
Side mounts setup
List of parts :
Scalar XL: 2 x 500mm smooth rods
Scalar M: 2 x 435mm smooth rods
2 top rod holders
4 M6x12mm screws
4 M6 T-Nuts
1 X axis (previously assembled)
2 threaded rods with their couplers (already assembled)
[Not provided] 1 hammer
Start by preparing the screws and Nut on the plastic part.
Note: The more recent Z axis smooth rods supports are very close to this picture.
The central guide for the Threaded rod has been removed because it deforms it leading to some bad quality prints.
Scalar XL: Also take 1 x 500mm smooth rod
Scalar M: Also take 1x 435mm smooth rod
Now insert it inside the hole at the outside of the plastic part.
Use a hammer to push it inside.
Slightly hit the plain side of the plastic part to keep it intact.
Scalar XL: Push the smooth rod inside the plastic part until the length inside is about 1 finger index long.
Scalar M: Push the smooth rod inside the plastic part until the length inside is about 1 finger index long minus 1 cm.
Do the same for the second side mount.
Scalar XL: Now take the X axis previously assembled, and insert the threaded rod so the the top goes out of also 1 finger index long.
Scalar M: Now take the X axis previously assembled, and insert the threaded rod so the the top goes out of also 1 finger index long minus 1 cm.Now take the X axis previously assembled, and insert the threaded rod so the the top goes out of also 1 finger index long minus 1 cm.
Continue with the second side. You should have something like the picture:
Now slowly slide the smooth rods inside the linear bearings on each side of the X axis.
Slowly approach the smooth rod from the linear bearing. Slide them very slowly inside and « DON’T FORCE« .
WARNING: The LM8UU linear bearings are made with very small balls. If the smooth rod is not aligned with the bearing, and if you add force, the balls might get out of the bearing.
At the top level of the assembly, slowly slide the threaded rod inside the top mount plastic part as shown in the picture.
Do the same for the other side.
In the end you should have something like the picture :
Installation of the side mounts:
List of parts :
1 side mount previously prepared
[Provided]1 allen key
[Provided]1 small allen key
[ Not Provided] 1 Hammer
Place the side mounts on top of the stepper motor.
Start by the left side of the chassis.
Align the coupler with the threaded rod.
Push it up to the end. You can use a hammer and give some small sharp hits on the smooth rod in order to push it in it’s dedicated hole on the side on the plastic holder.
Then align the top side of the mount so that the screws can fit the top aluminum extrusion slots
Once aligned, just slightly screw 1 of the screws in order to prevent this side of the mount from moving.
On the other side of the mount (right side) start by aligning the threaded rod with the coupler and the smooth rod inside it’s dedicated slot.
Maybe you will need to align the whole side of the mount slightly using a hammer. You need to make sure this side of the mount is perfectly vertical.
Take a hammer and hit the middle of the X axis Idler until the side of the mount is perfectly vertical.
Now align the top mounts screws with the top Aluminum extrusion slot .
List of parts :
1 Z axis mount
[Provided] 1 Allen key
[Provided] 1 small Allen key
[Not Provided] 1 hammer
[Not Provided] 1 bubble level
Take the bubble level and align the right side mount vertically by placing the bubble level as shown in the picture.
The Bubble we are interested in the the one always horizontal. It must be in the middle of the 2 lines.
Once aligned you can tighten the screws on the top side mount. Make sure that the T-Nut rotate properly inside the Slot .
Now go on the left side and reposition your bubble level .
Check that the level is correct and the bubble in the middle on the 2 lines.
If not, you need to unscrew the top screw and adjust the top position in order to align the bubble in the middle of the 2 lines.
Once both side aligned you should have something similar to the photo
The best is to rotate the printer chassis as shown in the picture. The purpose is to make it easier to place the T-Nuts inside the aluminum profile Slot.The spool holder is made so that you cannot pre mount the screws + T-Nut before placing the plastic part.
Focus on the Z axis motor wire.
The goal here is to place it inside the aluminum profile slot.
Place it as shown on the picture .
The other side of the wire must exit on the top of the power supply module.
This cable will then get inside the slot the is maintaining the extruder module.
It should go behind the power supply plastic cover.
Slide it inside the slot so that it’s in place for the future wiring steps.
The wiring should look like this.
Connect the end of the 220V power supply plug to the power supply.
Then slide the cable inside the same slot used for Z axis stepper motor wire.
Now take a « short » clip.
Those clips are made to be clipped on top of the aluminum profile slot and only secure one side of the aluminum extrusion.
When you place it over the aluminum extrusion you should hear a « click » meaning it’s properly in place.
This clip will be used to secure the base of the cables inside the aluminum extrusion slot.place it just near the z axis motor support.
Now take a « long » clip.
This model allows to close 3 sides of the aluminum extrusion at once.
Place it at the other top end of the machine, just behind the power supply module. The U shape must allows you to keep in place wires that are on the side where the use of the short clip would be impossible.
Here, a bottom view showing the long clip in place.
You now need the spool holder with the « X10″ marking » .
This plastic part’s purpose is to hold and keep in place the plastic filament during printing.
Place it on the side as shown on the picture, perpendicular to the power supply module.
The best is to place it as close as possible from the extruder (so to the top of the machine) .
Here the inclined position should help you to align the T-Nuts with the fixation holes of the spool holder.
You can use a small screw diver to keep the T-Nut in place while inserting the M6 screw.
Once in place, just add the M6X12mm screw.
This should look like the picture.
Secure it with a 2nd set of T-Nut/Screw and that’s it..