3D Printing

I assume you're using the springs now until the PETG comes? If so, original or yellow springs? Try this, you might not even need to worry about solid spacers...

I honestly never had a reason for an ABL because my bed leveling simply never moves unless I am working on the hardware. Basically the key is to crank all four leveling knobs down completely closed, open up the back-left corner (where the heater cables come out) by half a turn, and the other three knobs by about 1.5 turns as a starting point. Move the Z switch out of the way and manually move the head down to where you would do the paper test, and get all four corners roughly level to each other. Now bring the Z switch back up until it just clicks, lock it there to set your home position, then power up the printer and do an auto-home to see where it puts your Z at. Then release the motors and move the head around to once again adjust the leveling knobs on all four corners, more precisely this time.

So a lot of people think that the paper test is "good enough" for adjusting the nozzle gap, but in reality you need to get this set withing about 0.05mm of the ideal position in order for that first layer to print correctly, and who knows the exact paper YOU are using? What I do to finish fine-tuning is to find a 5-point bed leveling test print and print that out at this stage. If the filament doesn't stick, the strands of filament have gaps between them or you can pull the print apart with your fingers, the nozzle gap is too large. If the surface of the print is really rough, the nozzle gap is too small. You can adjust each corner to the ideal setting, then your prints should work as expected.

Of course it can take several iterations of this test print to dial it in, but the key here is keeping the springs as tight as possible. Do it that way and they should never move -- it's currently been well over a year since the last time I even checked mine.

Oh one more thing to watch out for... after dialing in the corners, lay a straightedge diagonally across the bed in both directions, you might see a warp one way but not the other. This is the bane of four-point bed leveling, but it basically means you have two corners a little too loose/tight. Make very small adjustments to correct and it should bring the center into alignment as well. If your center is really low, you can use circles of aluminum foil to build up underneath the glass and get the whole bed perfectly square (mine required 13 layers, I have one of the original warped beds). This not only helps with manual bed leveling, but it also means if you go back to the ABL then it will have a lot less work to do and the bottom of your prints will actually be flat.