How to fix “Slanting” Bed Leveling Result
Even with bed leveling active the resulting 1st layer will have a “slant” to it where one side of the bed is higher than the other. There are a few things you can try to see if this is what is causing it. This is caused by mechanical issues with the printer, not the EZABL kit. The kits (and any other ABL system) cannot fix every issue with your machine, only issues with the bed itself.
Check your Z-Axis First
This guide is assuming that you already checked your machine for Z-axis issues. If you have not please read this guide here: EZABL – Z Axis Troubleshooting. Use the M48 test outlined in the EZABL guide to verify that you are getting a good sensor reading. A good reading is anything under 0.01mm of standard deviation. If you are getting a good M48 result then the issue is going to be mechanical on the machine. See below.
Check that your probe tip is parallel to the bed. It should not be slanted. Slanting can be caused by the mount it is on not being properly attached or when tightening the sensor nuts it can skew. If you are using the included washer remove them. They are not needed and can cause issues on some mounts.
X Gantry Leveling
Check that your X gantry is level with the printer frame, not the bed. You want about 1mm difference at most (lower is better) between the left and right sides of the X gantry. You can also get an adhesive-backed ruler (like this one) and put one on each side for quick measurement.
For dual Z machines see here: https://www.youtube.com/watch?v=tOOuJURIQ54
Single Z machines – check both sides: https://www.youtube.com/watch?v=vhcEA8PKi5U
How to square up your gantry: https://www.youtube.com/watch?v=TwVxkukxJlw
There are leveling blocks you can print to put under the gantry to adjust it quickly. If it is constantly getting out of level you will want to dis-assemble the X gantry and re-assemble it to make sure everything is tight AND squared up. See below.
On machines that use the aluminum extrusion with the roller wheels these must all be adjusted so that they roll when that part moves. They should have enough friction to grip the extrusion but not so much that you cannot force the roller to move if you hold the part it is mounted to. Too much tension can damage the bearings and cause issues.
On wheels that do not have eccentric nuts you can loosen them up and move them in the bracket. The holes in the mounting plates are slightly larger than the screws so there is some “play” so that you can adjust them. Hold the wheels in place and then tighten them back down to get them aligned properly.See our video here on how to check eccentric nuts: https://www.youtube.com/watch?v=gAJRw1X738s
For single Z machines like the Ender 2, Ender 3, Geeetech A10, CR-10, and CR-10 Mini all that keeps the gantry level is the pressure on the rollers on the right side. If the outer wheels and the inner eccentric nut are not aligned then it will constantly go out of level. This will result not only in the ABL system not working but your print will be skewed in the Z direction. If your wheels are TOO tight this will cause issues as well.
Make sure you have enough tension that they are moving when that axis moves but loose enough that if you hold the axis you can break them loose from their grip on the extrusion
Having your belts stretched too tight can cause issues. If they are over tightened it can cause the X or Y carriage to skew as it moves along. Loosen up your belt tension until when you move the carriage the belt slips on the motor gear that drives the belt. Then tighten up just enough so that it does not slip on the motor gear.
Z Motors Bottoming Out
Whether using the stock bed springs or something to replace the springs sometimes if you have a machine that had glass on the bed stock and then go to print on the bare bed the Z-axis will not move all the way down. The probe will get a good reading but since the probe sequence is a few mm higher than when you print the issue may not be perfectly obvious. On machines like the Creality printers, they have plastic or metal blocks that hold the Z motors. Sometimes when you print on a bed that is lower than normal your X gantry brackets will bottom out on these Z motor mounts. There are 3 ways to remedy this.
Add a few mm of washers to make the bed sit up higher. The solid mounts we sell are meant to be used with machines that have the glass on top as that is what the machines ship with. In some cases depending on the machine this can be 1-2mm too short and can cause the Z to bottom out.
Sand or cut off 5mm at a 45 degree angle the corner of the Z motor block that holds the motor. The X gantry brackets have a slant to them and shaving the corner away will let them travel lower without hitting the Z motor block.
You could also print a new Z motor mount with that part cut out already if you do not want to modify the factory parts. Here is one that someone made for this exact issue: https://www.thingiverse.com/thing:2474909
If your cables going to the hotend are too tight then what can happen is as the hotend moves the cables pulling on the hotend can skew the sensor reading. Make sure your mount is not flexing too much and make sure the eccentric nut on the bottom of the X carriage is properly adjusted. Typically these have 3 wheels on them and they all should be rolling smoothly on the X gantry extrusion.
Squaring up your printer
The low-cost printers from China are assembled quickly and also settle during shipping. This can mean that your printer is “out of square”. If you have a Wanhao i3 you can brace the Z with a DIY kit (there are many on Thingiverse) or with a kit like this one. You can check the square of the frame parts with a ruler like in the picture below or if you have an actual square tool you can use that. You should check all parts of the printer frame.
Most adjustments can be made by loosening up the screws that hold the piece of extrusion that you are working on and then holding them in place when it is square as you tighten the screws back down.
Notice the gap between the bottom of the ruler and the Z extrusion. There should be next to no gap on the top and bottom if everything is square. After adjusting the gantry notice that there is a mostly even gap from top to bottom. This is how it should be.
If everything is square you can try and change the sensor calibration. Try calibrating the EZABL with the nozzle 3mm from the bed instead of the recommended 2mm. For the EZABL mini try it with the nozzle 1.5mm from the bed instead of the recommended 1mm. Run the M48 test to verify that you are still getting a good standard deviation (under 0.01mm) and adjust your Z offset (this will be higher after adjusting). Note that this is not usually needed but a few customers said this worked for them so we felt it was worth mentioning.