I’ve had this issue for quite some time.
Balco printer, from Aldi UK a few years ago.
HE180021 but board version 5.1. I’ve used firmware ADVi3pp-Mainboard-4.0.6.hex (not the HE180021 firmware because that smashes the nozzle into the bed).
I don’t have BLTouch. I don’t have Z-Braces.
When I do a manual level, I can usually get the 4 corners (1-4) at a similar level using a feeler guage.
At points A (front middle), 5 (middle middle), and C (back middle) and usually D (right middle) the nozzle is touching the bed.
I’ve tried the things listed here:
I haven’t tried Z-braces (I also can’t print, so no Z-braces for me yet), but I’ve eyeballed with a set-square, and I think it’s square.
I’ve tried to “untwist” the x-axis rods in case that’s my issue, but it hasn’t made a difference.
I’ve tried adjusting the rods using the screws as per this: BLTouch leveling differences from left to right side of heated bed
Could my issue be that both sides are twisted in the opposite direction, and that would cause the nozzle to be consistently lower in the middle? I’ve tried to get my head around which way I need to twist things, but my attempt failed and there’s no change.
I’ve previously tried rotating the rods 180 degrees (in case they’re bent).
I’ve tried a glass bed in case my heated bed is warped - no change. I even used just 4 small pads to sit the glass on the bed, to “raise” it above any possible centre-warp. I’ve flipped the glass, in case that was warped, but no joy.
I bought a manual-deploy probe and edited ADVi3++ version 3 (I don’t remember the point version) to enable G29 automatic levelling - mesh was measured, confirmed high-points, but it didn’t help and first layers still fail.
I haven’t (yet) tried editing ADVi3++ version 4 to use the probe. *edited to add: I’m not sure I will try editing version 4 to use the probe - I think too much has changed since a guide I used for editing version 3.
I’m all out of ideas of what to try. I haven’t printed anything for over a year now, and I’d given up. I figured I’d give it once last try before chucking the printer in the bin.
Any suggestions of thoughts on what I can try (preferably stuff that doesn’t involve printing something to fix it)?