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The issue of layer bulges have only happened to me when using Ender 3 and Ender 3 clones, though I assume it could be possible on many machine types, especially those with only one leadscrew.
I have a recently played around with a lot of trial and error, but there seems to be
one main culprit: a leadscrew that isn’t perfectly 90 degrees.
This is due to either a misplacement of the z-stepper motor or misplacement of the area the leadscrew is threaded into the mount, or both. This causes the leadscrew to be slightly angled from a perfect 90 degrees. There are a few solutions to this problem:
Remove Z-hop
This is likely the smartest solution for most inexpensive printers. Once I removed a Z-hop, those layer bulges went away entirely. I have recently learned that inexpensive machines should not have a Z-hop and should be reserved for well-built machines or Delta printers.
In the above photo, I have two prints that have exactly the same settings on an Ender 3 V2, but the one on the left has a Z-hop and the one on the right does not. This squished layer happens because it is more difficult for your stepper motor to raise in the Z-direction than to lower. When you have a Z-hop of 0.2mm, your printer may only raise 0.19mm, then drop back down 0.2mm, causing a squished layer.
This is definitely the easiest fix for this layer bulge problem and what may work the best for you.
Check leadscrew to see if it is bent
Take your Z-leadscrew and lay it on a flat table. Roll it back and forth and see if the rod is straight. Any bends will be noticeable when rolling. If this is bent or curved, then unfortunately there isn’t much you can do other than order a new leadscrew. Just make sure to purchase the same size and pitch as your current leadscrew, then upon replacement you should hopefully notice a big difference.
Clean and lubricate your Z-rod
As mentioned with mandatory maintenance, you should keep all of your rods lubricated. I would recommend removing the leadscrew, then cleaning it entirely in isopropyl alcohol to remove all the gunk.
Then grab some white lithium grease, or your preferred lubricant, and cover the entire threaded rod. This will allow for easier movement and less likelihood this issue will occur.
Check to see if leadscrew falls straight into Z-stepper coupler
Loosen your stepper motor coupler and lift the threaded rod out of it. Raise your
carriage to at least the midpoint, then thread the leadscrew down and see where it falls into the coupler. If your leadscrew doesn’t go straight into the coupler, this can cause your leadscrew to not be perpendicular to the build plate and lead to layer bulges.
It is fairly common on Ender 3’s for your leadscrew to line up with the back of your coupler, as if your stepper motor needs to be pushed back a few mm. This can be fixed by adding a spacer to the stepper motor mount, so that your stepper is set back slightly. There are new mounts you can print for your stepper on Thingiverse, or you can add your own spacer.
If your leadscrew hits to the right or left of your coupler, this may require a new
stepper motor mount that is adjustable. With these mounts you can adjust your
stepper left or right to line up properly with the leadscrew.
If that doesn’t work, or you would like to try another method, check the next step.
Purchase a Spider Coupler
Spider couplers allow for compensation if your leadscrew doesn’t line up perfectly. You can get a set of two for about $15 and are well worth it if you are having this issue.
Bend the Z-Carriage to be 90 degrees
One of the main problems is that the mount that holds your Z-leadscrew nut and
attaches it to your frame is slightly bent and not a proper 90 degree angle. I have
watched videos where individuals actually just hammer and bend the carriage back to the proper angle, though I have not personally tried this method. A video titled “Creality Ender-3 Z-Axis Alignment Correction” by Ronald Walters on YouTube goes over this exact method. This should result in fixing the problem, though it may be hard to visually see if you are at a proper 90 degrees without tools that will help.
You can also just reprint the entire body. I tried this by printing the design by
hunterius_prime on Thingiverse, though this unfortunately did not solve my issues.
Add a second leadscrew
This costs a bit of money, but adding a second leadscrew can compensate for any issues with your other leadscrew. Having two leadscrews is a good upgrade to have regardless, so it’s something to think about. That said, the main issue is due to the manufacturer not having the leadscrew lined up perfectly through the mount and the stepper motor.
This means that the only real solution is to fix this alignment. Adding a spider coupler or printing a new mount for your stepper isn’t a perfect solution, though it may work. This can be very difficult because it is hard to even see if the leadscrew isn’t a perfect 90 degree angle with your naked eye, meaning it is hard to tell how far or in which direction you need to change these things.
If you are able to tell how your leadscrew isn’t angled properly, then you can fairly
easily design a new mount for your z-stepper motor, making the leadscrew line up perfectly with your mount.
If your leadscrew isn’t the issue, you can try adding an anti-backlash nut. One individual I spoke to was able to completely fix his problems by doing this. So if your leadscrew is properly lined up and not bent, then it may be worth buying this inexpensive item to prevent your carriage from dropping when it shouldn’t.
All of the above said, the easiest solution is just to remove your Z-hop. Removing
the Z-hop and adding “Avoid Printed Parts when Traveling” will drastically improve your print quality if you are having bulge issues.
sure you turn on “Avoid printed parts when traveling” in your slicer to prevent parts being knocked over.
• If your leadscrew is bent or curved, you will need to purchase a new one.
• Clean and lubricate your leadscrew.
• Compensate for a leadscrew that doesn’t line up perfectly with your coupler by
either adding a spacer to your stepper mount, printing an adjustable stepper
mount, or purchasing a spider coupler.
• Bend the metal carriage that holds onto your nut that attaches the leadscrew to
your X frame so that it is a 90 degree angle.
• Add a second leadscrew which may be a little costly, but will help compensate
and overall make your printer better.
• If your leadscrew is nice and straight and lined up and you are still having this
issue, an anti-backlash nut may help.