Levels, Offset and Adhesion are the three most common words in the world of 3D printing. As a beginner they confuse and frustrate you. Then once you are a master or competent they will continue to surprise you. Rage Against The Machine never specified what type of machine they were angry with but you can bet it was a 3D Printer!
What follows are my reflections on setting up the different printers I have owned and do own. And how I have resolved the levelling, offsetting and adhesion issues I have encountered through day to day printing.
Check your foundations.
Is your printer stable, level and square?
Does the base of the printer feel stable. If you need to place a soft mat under the printer to stop any movement – do this.
Use a level and set square to check the fixed structure of the printer is correct. I like to pop a little thread lock on my bolts when I build the machine to help keep everything snug without having to overtighten.
Use the ruler measures printed on the Z Uprights and/or get a small spirit level and check that the bed and/or XBeam is level to the eye and the rest of the printer. In the case of the bed is it level left to right and front to back.
Good foundations are going to save you time later on.
Level the Bed
If you are levelling the printer out of the box you will probably need to back off the dials 1-2 complete turns each so you have some adjustment in both directions.
The Ender (Plus) provides a built in Bed Levelling Feature which moves to five points on the bed. The user then tests each corner with paper (0.1mm) and adjusts the corner screws/springs to bring the bed level. Creality suggest doing this a few times as each time you bring the bed closer to level. In the UK it seems that a Lotto lottery slip is the perfect thickness.
Other printers such as the Eryone Thinker you need to manually move the nozzle to each position and check the offset/level.
At this point I would mark the most forward facing groove of each dial with a white tick so I have a reference point to how much the wheel has moved.
Without the feature above (or in addition) you can use Pronterface, G29 Marlin Command and a bit of spreadsheet action to get a mental image of the bed level. If you connect the printer to Pronterface (other Slicers provide the same features) you can send G28 (Autohome) followed by G29 (Auto Level) to get a grid that can be copied/pasted into a Spreadsheet.
Once you have pasted them into your spreadsheet software you can analyse them using a mixture of conditional formatting with max, min formulas subtracted to give range. I complete it eight times because that what fits on my laptop screen.
The Ender now reports the auto level mesh as:
Setting the Offset
At this point you need to set the Z Offset between the nozzle and the BL Touch. The manual for my Ender+ says a 0.2 feeler but this was too high for me so the faithful UK Lotto slip (0.1mm) was brought back into action. Adjust Z+ / Z- and then once you are happy press Z Home.
The Ender seems to do this ok without having the bed/nozzle at a working temp but other printers are better with their offset set when the bed is at 60deg and the nozzle is some thing like 160deg.
Lots of manufacturers provide funky non-stick textured surfaces on their printer beds. A mooch around the forums quickly informs the observant that these are often a cause of problems.
My advice is flip it over to a smooth glass side or grab a piece of mirror and use a splash of 3DLac to help adhesion. Mirrors are ideal as they will be flat unless its one you have borrowed from a hall of mirrors maze!
Keep the bed clean and use 3DLac
Assuming here that you are using the heated bed appropriately also keep that glass bed clean. Yes you can do a few prints on after the other before needing to reapply, clean or give the bed a quick wipe. Only experience will teach you this. Monitor the first few levels – if its not going well – stop the print, clean the bed, spray and restart. Sometimes a quick wipe with a tissue and IPA will be enough to clean up the bed that a quick squirt will do. Sometimes the glass needs to be taken from the printer and given a good clean, taking it back to the bare glass before starting over.