Poor gantry squaring can cause a number of problems.
Notice that the idlers get "pinched" when moving the X extrusion back/forth (this is shown with loose Z joints).
Pinch.mp4
This can potentially cause:
- First Layer issues
- Z belts rubbing against the gantry's printed parts
- X axis to be "racked" at the front but not the back (or vice versa)
"Bonus" steps 14-16 can also help with first layer and with gantry stability.
1) Modify the timeout
setting your [idle_timeout]
config section. Set it to an arbitrarily high value (in seconds) and reload
.
- This just gives us time to work. We need the Z motors to be energized and holding for the whole process.
2) G28
, then QUAD_GANTRY_LEVEL
.
3) Jog your gantry to the center of the build volume using the LCD or web interface.
- This will give you space to work. You need easy access to both the bottom and top of your gantry.
4) Turn off ONLY your A/B motors using these g-codes:
SET_STEPPER_ENABLE STEPPER=stepper_x ENABLE=0
SET_STEPPER_ENABLE STEPPER=stepper_y ENABLE=0
5) Loosen your A/B belt tension fully.
-
This prevents the A/B belt tension from pulling the gantry out of alignment while you work on it.
-
Your belts should be fully disengaged. If there is still remaining tension with the idlers fully backed off, you may need to release the belt ends from the X carriage.
6) Take off your left/right side panels.
7) Unscrew and drop your lower Z joints.
-
Your gantry will now be floating on just the belts.
- Make sure your printer is on a fairly level surface, otherwise your gantry could swing too much to one side. (it doesn't have to be perfect, just don't do it on a hill),
8) PARTIALLY loosen all connections to the extrusions.
-
You need all of these bolts to be loose enough to freely adjust against the printed part on the extrusions.
-
⚠️ ⚠️ Where there are Z belt clamps, ensure that you do not loosen the bolts so much that the Z belts release. Only loosen enough to allow for adjustments.⚠️ ⚠️ -
X/Y joints (repeat for both sides).
-
A/B joints (repeat for both sides):
-
Front idlers (repeat for both sides):
9) And now - what we have been prepping for! Adjust your gantry so that it sits perfectly on top of the lower Z joints.
-
This involves moving gantry components further apart or closer together along the extrusions:
-
Your gantry should align so that:
-
Ensure that you do not inadvertently rotate your A/B joints during this process.
10) Tighten every extrusion bolt again, except those in the X/Y joints. (you will tighten those during step 12)
- Ensure that your Z joints still align properly. Sometimes tightening can move things around.
11) Re-install your lower Z joints and lightly tighten the M5 bolts.
- Do NOT hulk them down yet, or even make them tight. The "ball joint" should still be able to articulate completely freely.
12) Follow 📄Nero's de-racking video.
- Make sure to come back here afterwards! The following steps are still important.
13) 📄Re-tension your A/B belts (to 110hz over a 15cm span).
- Don't miss the video link in that post. It's easy to overlook.
- Apps:
- Android: Gates Carbon Drive (select "motorcyle" option) or Spectroid.
- iPhone: Gates Carbon Drive (select "motorcyle" option) or Sound Spectrum Analysis.
14) Reinstall your panels and fully heatsoak your printer for 1½ - 2 hours minimum.
15) QUAD_GANTRY_LEVEL
3-5 times to "settle in" the gantry (and level it for the next step).
- If you are having new Z accuracy issues, you may have left your Z joints a bit too loose.
16) Open the front door and fully hulk-tighten the M5 bolts in your Z joints* while it's still hot.
* Unless your parts are printed in eSun ABS+. It's more brittle than regular ABS. Just tighten them "pretty tight".
- This does two things:
- Somewhat "locks in" your QGL at its state in full thermal expansion.
- This has helped a number of people with their first layer issues.
- Stabilizes your gantry.
- If you had it "tight but not too tight, so the Z joints can still articulate" (as is often recommended), you will notice that your gantry displaces back/forth while printing.
- This can help with ringing and layer consistency.
- Somewhat "locks in" your QGL at its state in full thermal expansion.
17) Restore your [idle_timeout]
settings (changed in step 1).