New PEI sheet and auto bed-leveling...WTF

So I was able to get the PEI off my print bed, but I ran into a problem. After I removed the PEI, I wanted to see if I could print some ABS on blue painters tape (and glue stick) on top of aluminum bed. I performed z-offset wizard (and manual bed leveling) and started the print. After auto bed leveling, on the initial pass where the extruder traverses the length of the bed and prints a line, the nozzle ran into the bed about midway and stalled, scratching the bed. I immediately aborted the print. Maybe it was my fault because I did not put tape over the entire bed surface, only a 7" x 7" square in the middle. That might've confused the IR sensor during auto bed-leveling.

Anyways this got me thinking. The new PEI sheets I have are clear. What's going to happen during auto bed leveling after/if I install the new sheet? Am I going to run into this same problem because the IR sensor effectively "can't see" the sheet of PEI (assuming it can't)?

To be honest, I'd rather have the ability to turn off the auto bed-leveling routine at will, which Robo tells me is impossible. After going through z-offset, then bed leveling wizard, then fine tune z-offset, what's the point of having another bed-leveling routine that will completely override the settings you made previously (I'm assuming that auto bed-leveling can and does change the settings, but I could be wrong). Regardless, what IS the point of the auto bed-leveling routine?

I would appreciate any insight you all might have on this and I'd really like to know if I CAN turn off auto bed-leveling, regardless of what Robo says.

 

Awesome, thanks guys. I will go ahead and get rid of it. I am fairly good at leveling the bed on my R2; I've done it dozens of times. I honestly would rather leave it alone, but it's ridiculous for me to have to put painters tape on the ENTIRE bed for a small, 1" long part.

Have any of you had success with ABS and/or PLA on an aluminum bed?

 

I know, I would never print on bare aluminum. I had a 7" x 7" square sheet of blue tape in the center, but since it did not cover the first inch or so from the front (and sides and back), the auto bed leveling screwed up. So, when the extruder started the priming line just prior to printing, the nozzle ran right into the aluminum. I should've known better, but I'm getting rid of the auto bed level as I type this..................

 

Forgive my ignorance, but I'm not familiar with MESH or UBL. To be honest, I have no idea what that is.

 

Awesome, thank you!

I didn't even know it was possible to have multiple z-offsets in the software and have the machine make necessary corrections while printing. I thought that once the z-offset was specified, that was it for the entire bed. I initially thought that the variation in height on my bed was due to the sheet of PEI (and it was.........mostly). But, I do have some slight variations on the bare aluminum, so I will employ one of these methods once I am more familiar with them.

 

I was able to remove auto bed leveling (thankfully) and actually have a successful print. I just printed two small parts, the stylus holder and a z-axis lead screw plug. I printed them in ABS (235C; 85C) on blue tape with glue stick. Adhesion was actually very good. I was impressed with how well the glue stick and tape worked.