Can't get bed to level properly

Question

I am new to 3D printing and just purchased an Ender 3 V2 about two weeks ago. Since I've got it, I've been having trouble leveling the bed. I've tried watching videos, but they don't say how much friction on the paper is good or bad. I have even tried foil, playing cards, and a business card but still can't tell if it's good enough or not. Then when I would try printing calibration squares and adjust as it prints, but when it prints all looks good when printing the outside ring, but when it gets to the square parts there are bumps on the print from the nozzle being too close. Also when I seem to have corner perfect, when it gets to the center it's too close to the nozzle and doesn't even print. I'm using the stock glass bed so I'm not sure if that could be the issue. This is getting frustrating as I really want to start printing. And I want to save money for other parts and try avoiding purchasing a BL Touch if I don't need to. Am I doing something wrong? How can I get this resolved?

Forgot to mention, I upgraded the springs to these yellow ones on Amazon.

Answer 1

Step 1: stop using paper and get some feeler gauges. The gauge should be able to just barely pass under the HEATED nozzle.

Step 2: What are you using for bed adhesion? I use Elmer's white glue. After you think you've trammed (aka levelled) the bed, apply a generous layer of the glue in a coat on the bed. Let it dry.

Step 3: Verify bed level with a large square print that will cause the head to move to the outermost parts of the bed. Stop the print after a few outlines. Try to remove the print. If some areas are easier to remove than others, apply another coat of Elmer's glue to those areas.

Note: Do not hold down all four (4) corners of the glass bed. The aluminium plate is not going to be flatter than the glass. Only attach the glass to the bed on one side of the bed. I use the side that is furthest from the nozzle.

Answer 2

If you find the bed on an Ender 3 doesn't seem to "take" a level - in other words, if you keep trying to level it and things seem right, but then it's obviously wrong when you actually start printing, and checking the leveling doesn't seem to match what you set before - the problem is most likely in the Z axis mechanics. The Z assembly (including the X axis gantry) is highly overconstrained, between the 6 wheels, the lead screw nut, and the 4 screws attaching the gantry to the Z carriages. When it's not functioning properly, whether from fighting constraints, overtightening, undertightening, etc. you can end up with really bad reproducability* of position in the Z axis, so that homing and moving to a particular Z coordinate gives different results each time you repeat, due to which components bind and which ones give.

If this is your problem, I don't have a good system for solving it. I've fought with it on and off over 2 years of owning one of these machines. At least you should check that the 2 screws holding the left side of the gantry to the Z carriage are very tight (note: they're hidden and inaccessible without taking off the top bar and raising the assembly off the Z extrusions) and that the gantry is mounted level to the carriage bracket, since any play here will ruin everything. One easy thing you can try to confirm whether you have leveling reproducability problems from Z axis problems is disconnecting the right side carriage entirely and tying it off at the top so it doesn't interfere; you can do this without disassembling anything else. This lets you operate the Ender 3 "as an Ender 2", i.e. with a cantilever setup. It's less rigid and probably not a good choice overall, but if it solves your problem then your problem is almost surely something in the overconstrained Z system and now you know where to look.

Answer 3

First, make sure the slate of glass is straight, this can be checked with e.g. a metal ruler on its side against the glass surface. If the glass isn't straight (which should be per the production process of glass, but there have been reported bad glass beds) you never get a perfect level over the whole bed. Also make sure the glass sits on a clean heated bed plate (no debris between the heater and the glass).

Second, level the bed, start with powering the printer. You need to sequentially do the following as adjusting the one corner (screw), affects the other corners (continue this until the bed is level and the one corner doesn't affect the other corners anymore):

• Home the machine,
• heat up the bed and nozzle to e.g. PLA printing temperatures,
• move the nozzle close to a corner (a different one than the previous corner),
• put a piece of plain printing paper on the bed,
• lower the nozzle to Z=0,
• adjust the screw in that corner until the piece of paper can be dragged under the nozzle with a slight resistance,
• repeat by starting with homing the printer.

After several rounds of leveling and having a level/straight bed to begin with, you should have a leveled bed that has been leveled against the printers' X-axis.

Now, when printing something it should be level, the only thing that might not be correct is the distance between the nozzle and the bed. E.g. some users prefer a larger distance between bed and nozzle when printing PETG (not my personal experience, but a generally accepted truth). This distance can be tuned without having to re-level your bed; you could if you want to use a thicker or thinner paper, but you can easily change the Z=0 by redefining the Z=0 level at e.g. 0.10 mm height if the nozzle to close. Some slicers even allow you to add an offset (e.g. the "Z Offset Setting" plugin in Ultimaker Cura from developer "FieldOfView").

When you have dialed in the distance also correctly, you should get perfect prints.

Do note that a common issue with these over-constraint "cantilever" printer designs is that by powering a single side, the opposite needs to follow exactly, that is a challenge with that many parts. My preference is using dual lead screws, preferably driven by a timing belt for Prusa type printers.

Addressing the BLTouch part in your question; before you wander in the world of automatic bed leveling (AB) you should first master getting a level bed, or fix the X-axis rollers on Z beams. For ABL you also need to level your bed first else you get non-square prints. The roller solution is one of the major drawbacks of these printers, you need to make sure the X-axis (aluminum extrusion bar) stays level (or better trammed) in relation to the bed level, loose rollers should be properly tensioned.

Answer 4

Don't worry too much about it. If you print with a first layer height of 0.3mm, bed levelling only needs to be approximate. If that doesn't work, and you cannot get good bed adhesion, try printing onto blue painter's tape (ScotchBlue). This makes a very forgiving build surface. You will need to clean it well with isopropyl alcohol (or acetone), since it is coated with a wax-based release agent that may prevent the filament from sticking. Once you have got used to printing, you can then refine your bed-levelling techniques.