I’m having an issue with the BL touch on my ender three pro. I’ve got everything working however it does not bring nozzle down low enough to the print bed. I have tried Z offset but adjustments but it still leaves too far of a gap. Any tips?

I had a similar issue with the CR Touch. No matter what Z offset that I had, it wouldn’t print close enough to the bed. At one point it it should have been printing under the bed. I took it off and went back to manual leveling. It’s faster anyway.

Darn it! That is what I did on my V2. Was hoping to get it right this time.

Are you changing the z value in marlin (or klipper)? Been a while since I did marlin but if that initial z value is wrong you'll play hell getting it set manually.  Isn't there a z wizard in marlin?

I was flashing with new firmware from Creality- then tried some other expert firmware. Nothing worked. I took it off and am back to manual.

The firmware version can cause issues. I had to try a few flashes before I got one that was stable for auto bed leveling. And this version still errors on pronterface g code commands. It’s part of the ender experience…

This is why it's good to compile your own firmware.

I'd seriously consider running Klipper instead.

When you adjust the Z offset, does the axis move? I had occasional issues where it would not move if I had previously disabled the steppers for moving things around. I also noticed that the SD card has to be installed, or it won't save the settings.

I had issues with my CR Touch and the Ender 3 Pro board/firmware. Seemed to never work correctly. Finally got tired of it and put a bigtreetech v3 with display combo. Still had issues with bigtree's firmware. Went to TH3D and grabbed their firmware and compiled my own. Works much better now. Babystepping can be key while printing. Also I found if you leave the stock springs and adjusters on, i still needed to manually level my bed every once in a while before running a ABL.

I would start with compiling your own on the stock board. If that doesn't help then maybe go with a better board. Mine is a lot quieter now. It's the one I travel with for work, so sometimes it's running in a hotel room with me at night.

I will say that with the stock board and CR Touch after it homes when you are trying to set the Z offset it lifts like 10mm above the bed. Took me a long time to understand how to get the offset correct. My CR10 with ABL would lift just a few mm after homing when setting Z offset. Other things are after homing, the mesh may be deleted so you have to rerun your ABL. Another issue I have heard is that fade height being set to anything other than 0 when running ABL may cause issues also.

Having a single Z motor can cause issues. The gantry can sag when the head gets to the right side, especially if you have direct extruder setup. Make sure all wheels that have the concentric nuts are adjusted properly.

Sometimes using a terminal like pronterface helps too. If you run a M503 it should give you the mesh. This is key. You can scroll up to see the mesh change.

Another issue I have seen with mine with the stock board is running G29 multiple times in a row. It seemed to mesh using the numbers from the previous G29, which added height. I could never confirm this properly  or find anything in searches that this happens. I know it sounds weird but I would see my numbers go up in pronterface and my first layers would be horrible.

I have been struggling with my Ender 3 pro for almost a year. Great little machines stock but once you start upgrading it you start running into little issues that are frustrating IMHO. My CR10 and D3 Hero are to a point where I can start a print and walk away. My CR10 is a shadow of its original form but it is bullet proof.

Here is the board I am currently using in my 3 Pro:

BIGTREETECH SKR Mini E3 V3.0 Control Board + TFT35 E3 V3.0.1

Aurora Tech, Chris's basement and Teaching tech are my 3 go to on YouTube.

Below is the upgrade of the v3 board. Watch out for the pins for whatever sensor you are using. I had to do a little research and split the connector to get rid of the Z limit switch. Also it helps to get bootlace ferrules and JST connectors from Amazon.

https://youtu.be/dtwWnz2-5VQ

I hope this helps

What does the auto leveling actually do? Is it just a z axis compensation as it moves across the bed based on the mapping it created?

https://all3dp.com/2/best-3d-printer-auto-bed-leveling/#:~:text=Auto%2Dbed%20leveling%20

As a glutton for punishment, I just got my Sovol SV 06 set up and running so I decided to try to install dual Z and the BL touch again on the E Pro. Dual Z went smoothly and test print turned out great. Now I have the BL in and working, except I can’t move the Z DOWN once I auto home and it auto homes to the very top. I have no issue using motion Z to move it, but once it is auto homed it will NOT move via the motion prompt,

That, and it also sets the nozzle height to the proper height for every print so even if the bed gets tweaked a bit it still is leveled via nozzle compensation.

I had to compile my own firmware to get it to work properly. The preconfigured nozzle offsets are completely wrong and the probe isn't actually probing where it thinks it is probing.

I have to run the BLtouch routine twice every time I start my printer.
I'm not sure why, but the first result is always too high, and the second is always right on.

You are manually setting the bed to temperature before you run the routine?

Kharn

Regarding z not changing, were you telling the machine to move below the 0 (zero) position? Software endstops do that if enabled. M211 can be used to disable/enable them and allow movement into negative territory.

I was trying but the software was preventing it.