@beejack
agreed. The Marlin bugfix fork is great. But, it's for people who want to edit their own parameters and do more in depth customizing. I enjoy that. I've been trying to stick to Creality specific releases in my comments to make it easier for those just getting into Gcode controllers to have an easy time with updates. I'll be glad to hear about anything new and exciting you find along the way though! Thanks.

@Pontymython
I have the same issue. Initially, the bed was more planar. Now, like yours, mine is concave with the center lower than the corners. It only took a couple of heated prints to change.

I've thought about ordering a new bed assembly and measuring all of the parts across several heat/cool cycles to see what's really happening. If I had to guess, I'd say it was extruded/rolled aluminum causing the issue. It would probably be a cost problem to machine it from vertical cast aluminum like ATP-5. Though with the different thermal expansion coefficients of the aluminum and glass, it may not make that big a difference.

Just thinking in type.

Went with the BLTouch to compensate.

It depends on the type of polyamide (nylon) filament you're using. I have been printing with a filament that requires a 250°C HotEnd and 90°C plate. The filament guide PTFE tubing that comes with the printer will not support that for long enough to print anything useful. I traded out the portion in the hotend only with Capricorn PTFE tubing. It's working well enough now.

You can follow the CHEP video for installing Capricorn in the hotend:
https://www.youtube.com/watch?v=7tCxO17XZtw
He has links to Thingaverse for the washers he printed to bridge the tubing types.

Or, you can replace the entire run of tubing with Capricorn.
If you're going to cut it, you can buy a kit with the cutter included to make better squared ends. It's not that hard to do by hand, but takes some practice.
https://www.amazon.com/Authentic-Capricorn-Filament-Extruder-Fitting/dp/B08BHVWNWK

You'll also need to make or buy an enclosure to prevent draft warping.
I've been using the Creality branded enclosure with good success. It's a bit picky getting the machine into and out of the enclosure, but gets easier when you figure out a strategy for your unit.
https://www.creality.com/goods-detail/creality-3d-printer-enclosure

@Cheezzer
Did Admin's suggestion work? (it should have)

@Tim33
Check to make sure the belt is in the middle of the aluminum slot from front to back. If the rollers are set correctly, assuming there is no warp in the Y axis profile aluminum, they should not bind differently along the beam.

Things to check:
Belt position
Belt tension
Adjustment of the pinch roller under the print bed
Make sure the wiring and harnesses are tucked out of the way

Good luck! YouTube is a great resource for Ender machines.

@admin
Thank you. I was able to wire the BLTouch V1 directly to the available port by wiring a proper JST-XHP 5pin connector. No additional riser/adapter boards required. All works well. I noted that the V1.3.1 firmware did not work correctly for me. I was able to flash the V1.1.1 firmware with update of control board and remote controller display. All is well.

@admin
The BL Touch unit retracts during normal operation, and is extended well beyond the nozzle during bed leveling. Is the Z-axis limit-switch still valuable for preventing catastrophic bed collisions if it is adjusted properly after manual bed leveling? (as long as it is low enough to allow a good first layer and high enough to prevent more than just glancing contact)

@daviesj
Thanks for the concern. The machine has been used for less than 12 hours. It's been out of the box for a week. There is some dust on the machine now from some CNC routing without enough suction at the dust shoe. I need to give it a good vacuum before I use it again.

@frated
BLTouch v1 mount on Ender 3 v2

• Take the screw out of the heater assy housing in back as shown.
• mount the BLTouch with mount without that screw
• use a scribe, nail, something sharp...to scribe the mount where the screw hole is
• drill the hole that you marked.
• reassemble with the new screw through the mount and into the housing as shown.

@admin Just got an Ender 3 v2. Glass bed was low in the center. This trick worked to adapt BL touch v1 kit, using v1.1.1 firmware. Rewired harnesses to a 5pin XHF to keep it clean. It works! Thank you.