ABL Settings Overview #
Our Unified 2 Firmware has specific settings to make auto bed leveling (ABL) probes work properly and provide a good user experience. Many people who are new to our firmware or ABL, in general, are not familiar with how this all works (mainly BLTouch or CRTouch users). The goal of this article is to educate users on how the firmware works to eliminate confusion amongst users who are not familiar with ABL systems. We follow best practices from Marlin and settings that we find through our years of testing ABL systems on actual machines.
Z Height After Homing #
When you are using ANY ABL probe with our firmware after homing the Z axis will show 5mm. This is to reset the probe detection to the OFF state. This 5mm is NOT included in your Z offset. This 5mm also does not mean that your Z home location is Z5, it is still Z0.
You should NEVER follow any direction from other sources that tell you to move the nozzle to the bed and then issue a GCode command to tell the printer that the new position is Z0. Your Z0 location is all calculated by your Z Offset value. If someone is telling you otherwise, they are wrong.
Probing Speeds #
In general, BLTouch and similar probes (like the CRTouch and other knock-offs) cannot run very fast probing speeds while maintaining accuracy. Our default speed for ALL ABL probes in the firmware is set to 8mm/s.
Super Fast Probing #
If you have our EZABL and your printer can handle faster probing speeds you can use the SUPERFAST_PROBE option to get speeds of 15mm/s. If you want to try this uncomment the option and then update your firmware. Run a few M48 tests. If your Z axis is moving smoothly (not losing steps) and your M48 probe test is reporting a result of 0.01 or lower then your printer can use the higher speed. If you enable the SUPERFAST_PROBE and you are getting poor M48 results and/or your Z axis is losing steps (usually this is heard by the motor vibrating/grinding noises) then you should NOT use the SUPERFAST_PROBE option on your printer.
Z Offset Setup #
What is a Z offset? #
Your Z Offset tells the firmware how much distance is between the nozzle and the bed after the probe detects the bed. Once you have a Z Offset set on your printer it will use this distance to calculate where your actual Z0 position is in relation to the nozzle and the bed.
Once you have the firmware installed and your probe is working you need to set your Z offset. If you have the EZABL this is documented in the installation guide. If you have another probe you can also follow the EZABL video below to set your Z offset.
Setting the perfect Z Offset #
If you are comfortable, you can also just set your Z Offset “on the fly” by adjusting it on the skirt of a print. You can see this in action in our EZABL EZTip video below. This is how we set our Z Offsets on all our machines in the TH3D shop and this is more accurate than using other methods to acquire the Z Offset.
