EZABL Pro Installation Guide

Welcome #

This guide will walk you through the steps to install the EZABL™ Pro sensor on your printer. Be sure to follow all the steps and if you have issues or a question, do not hesitate to reach out to us by visiting ContactUs.TH3DStudio.com.

There are optional accessories for the EZABL™ Pro Kit, such as the AC power adapter or USB power adapter, that are not included with the base kit as shown throughout this guide. If you ordered these options, they will be in the EZABL™ Pro kit package when you receive it.

We are always making things better, so the case or sensor may look slightly different than the pictures in this guide.

EZABL Pro (Base Kit)

Some printers have a slightly different installation process than is outlined in this guide. If a printer requires a different installation that deviates from this guide it will have an accompanying article. All these articles are linked below:

Different EZABL Sensor Types #

We have different versions of our sensors and while the guide applies to them all these are notes about the different sensors and where they vary. Keep these notes in mind as you read the guide.

EZABL Pro (18mm)/Pro Mini (12mm) – These came with blue or red strain relief on the tops of the sensors and your adjustment screw will be on the side of the sensor and is a brass color.

EZABL Pro-T (18mm) – These are black sensors with a grey cable. These came out in early 2023 and the adjustment screw will be either on the direct top of the sensor or very close to the top on the side of the un-threaded part of the sensor body.

EZABL Pro Micro (8mm) – These are our tiny probes. These do NOT have an adjustment screw and are preset at a 2-3mm detection distance. No calibration is needed on these. These will mount to the hotend with the sensor sitting 1mm higher than the nozzle.

Installation Video #

We have an installation video that is meant to complement this installation guide, not replace it. Check it out below:

Preparation #

Please Note: If you are not comfortable flashing your printer’s firmware, moving wires around, and/or taking your hotend mount apart, you should NOT be attempting this upgrade as you could damage the printer. Contact us with any questions before installation if you are unsure of upgrading. Support covers the product itself. If you need assistance with your slicer, tuning your machine, or other non-product related issues, please check out our communities at Community.TH3DStudio.com.

Before you begin you should have the following:

  1. TH3D EZABL™ Pro Kit:
    • 1x EZABL™ Pro Control Box
    • 1x EZABL™ Pro Sensor (size depends on your selection)
      • EZABL™ Pro Mini and Micro Sensors will have 2x Adapter Rings included
    • 1x Power Wire
    • 10x Zip Ties for Securing the Sensor Wiring
    • 1x Micro Screwdriver for Adjusting the Sensor and Screw Terminals
  2. Printed Parts to Mount the Sensor to your printer:
    • We offer 3D-printed mounts for purchase as accessories to the EZABL™ Pro kit as well as standalone items. There are mounts available for several printer models and brands, as well as your choice of PLA or ABS material.
    • We also include STL files for a multitude of mounts in our Unified 2 STL package.
    • You can also use custom mounts based on your printer’s fan shroud. You will need to measure and set your nozzle-to-probe offset settings accordingly. See the firmware CUSTOM_PROBE section for more information.
    • We do offer custom-printed parts if you need a special mount but do not want to print your own. Prices are about $10-30 (depends on the mount) for an ABS printed mount. If you want a custom mount to be printed, please contact us with the STL files for a quote.
  3. Latest copy of the Unified or Marlin firmware for your printer:
    • We have firmware for over 20 different machines on our website – Download from uf2.th3dstudio.com.
    • If you have a custom printer, see the notes in the firmware section of this guide for a link to the Marlin setup guide.
    • You will require a USB Cable to connect your printer to your PC to update the firmware in most cases.
    • Your printer’s mainboard may require you to install a bootloader in order to update the firmware. Please see bootloader.th3dstudio.com, the firmware page for your printer at uf2.th3dstudio.com, or contact us for more details.

If you are missing anything from the TH3D EZABL™ Pro kit please visit ContactUs.TH3DStudio.com. Email support is included in the kit for setup, install, and firmware questions. Phone/Remote Support is available at an additional charge.

Pre-Installation Checks

Before installing the EZABL™ Pro kit, there are a few things that we recommend double-checking to make sure the printer is in optimal condition:

  1. If your printer uses bed springs, make sure your bed is level and the springs are under good tension.
    • You can replace springs with aluminum spacers from a hardware store. We also sell solid mount kits that integrate both wiring strain relief and optional camera mounts (for select models) on our website.
    • Check all the wheels and eccentric nuts if your machine uses these.
  2. Run through the Z axis checks that are outlined in our Help Center.
  3. Make sure the power cord your printer uses has a grounding plug. If you are using an adapter and/or extension cord make sure they are also grounded. If it is not grounded, there can be electrical interference that can cause the sensor to not work correctly.
    • If you are using a separate power adapter, make sure the power adapter is on the same power strip as the printer.
  4. Depending on what mount you are using, printer model, etc., you may need additional screws. Most mounts use M3 screws so it would be recommended to pick up an M3 screw assortment from TH3D, Amazon, or your local hardware store.
  5. Some printers require a bootloader to load the firmware. You will need an Arduino Uno with some jumper wires. We sell a bootloader kit in the TH3D Shop that comes with the Uno and ALL the cables needed.
    • Any of the models with the 1284p chips require a bootloader.
    • Anet printers, CR-10, Ender 2, Ender 3, Ender 5, and Wanhao i3 all use the same process for the bootloader.
    • There is a video guide and information for flashing your bootloader at Bootloader.TH3DStudio.com and you will need an Arduino Uno to flash the bootloader using our guide.
    • Model-specific information can also be found on that model’s firmware download page: uf2.th3dstudio.com

Troubleshooting Information

If you should have issues with your EZABL™ kit, first visit our Help Center. This is where we document all known issues with the machines these kits are used on. If you cannot find a solution to your issue, you can visit ContactUs.TH3DStudio.com for support.

Connecting Power #

Connecting power to the EZABL™ Pro Module is easy and flexible.
You can power the kit with the included power wire to your printer power supply or, if you ordered the AC adapter/USB adapter with your kit, you can power it externally.

NOTE: Do not press the self test button with a sensor connected to the EZABL control board. It is only for use when directed to be used by our support team. This emulates the sensor trigger signal when pressed.

EZABL™ Pro Control Board Connections/Features

Separate Power Adapter

If you are using our AC adapter or USB adapter, simply the DC plug to the DC Power Input Jack on the EZABL™ Pro Control Board.

Directly Wiring Power

If you are wiring to your printer’s power supply, make sure that you match the positive and negative connections on the power supply and EZABL™ Pro Control Board DC Power Input Terminal. DO NOT connect to the AC lines.

The supplied wire has a red wire and a black wire contained inside the outer sheathing. Strip this back at both ends and then strip the black and red wires at each end as well.

  • Positive is labeled with + on our board and usually is V+ on your power supply. Use the red wire for this connection.
  • Negative is labeled with – on our board and usually is V- on your power supply. Use the black wire for this connection.

Use the included screwdriver to secure the wires in the terminal, DO NOT over-tighten.

If in doubt, send a picture of the wiring to our support BEFORE you power the machine on and we will verify the proper connections for you.

Z Endstop Connection #

The EZABL™ Pro Control board replaces your Z endstop switch.
It accepts 2 types of Z endstop connections – 2/3 Pin JST XH and stripped wires.

Printers with a 2 or 3 Pin JST XH Plug (Creality, Geeetech, Alfawise):

  • If you have a printer that uses a 2 or 3-pin JST XH plug then you can use the 3-pin header on the EZABL™ Pro Control Board.
  • If you have a 2-pin JST XH you will want to connect to pins 1 and 2.

Printers with soldered Z endstop wires:

  • If you have a printer with wires that are soldered to the Z endstop switch or one without a JST plug, you will cut the wires and insert them into the black screw terminal on the right.
  • Wire placement does not matter in this case. Use the included screwdriver to secure the wires in the terminal, do NOT over-tighten.

Endstop Connection Re-cap

After making the connection you should have the Z-Endstop wire connected from the EZABL control board to your printer control board. If this is not clear watch our video here: EZABL EZTips – Z Endstop Connection – YouTube

3 Pin JST Wiring Pinout information for advanced users

Pin 1 is connected to one leg of the optocoupler. Pins 2 and 3 are connected to the other leg and connected together to accommodate 3-pin and 2-pin end-stop connections. Only connections to pins 1 and 2 or pins 1 and 3 are needed. These should go to your control board on the endstop/probe Signal and Ground pins.

If your printer has 3 wires going to the Z endstop connection, please contact our support BEFORE connecting. You can contact us through ContactUs.TH3DStudio.com.
For Geeetech machines with a 3 pin endstop, please see our Help Center for wiring the Z endstop cable.

Verify Power and Testing #

When you power on your printer, the Power LED on the EZABL™ Pro Control Board will light up green. If the power LED is not lighting up, check that you have the polarity correct if directly wired. If you are using a separate power adapter, ensure that it is plugged into a power source that is turned on.

Next, plug the EZABL™ Pro Sensor plug into the EZABL™ Pro Sensor Connector on the control board.

To verify that the sensor is working, touch the tip of the sensor with your finger. The Red LED light on the Sensor AND the Status LED on the EZABL™ Pro Control Board should light up. Depending on your sensor, it may or may not also have a green power LED that will be lit (this will shut off when the sensor is triggered).

If the red LEDs do not light up but it otherwise has power working correctly, place your finger on the tip of the sensor while adjusting the gold screw on the side of the sensor clockwise until it lights up when you touch it. See the calibration section later in this guide for additional details.

Mounting the Sensor #

Now that we have the wiring completed, it is time to mount the sensor to your machine.

  1. Install the sensor mount for your machine and place the EZABL™ Pro sensor inside. Remove the bottom retaining nut from the sensor and insert the probe into the mount, then replace the bottom retaining nut to secure the sensor into the mount. (If you are using the 12mm “Mini” or 8mm “Micro” sensors, place the provided adapter rings into the mount, then insert the sensor as stated.)
  2. For 18mm sensors, adjust the height of the sensor so that the bottom of the sensor sits 2mm above the tip of the nozzleFor 12mm “Mini” or 8mm “Micro” sensors, mount the sensor 1mm above the nozzle tip instead. The easiest way to do this is to manually lower the tip of the nozzle to the bed, then use a 2mm (or 1mm for Mini or Micro) spacer to set the height of the sensor. You can also use a pair of coins or one of the flat wrenches from your printer’s toolkit to approximate a 2mm spacer.
For 18mm sensors, mount the sensor 2mm above the nozzle tip. For 12mm or 8mm sensors, mount the sensor 1mm above the nozzle tip instead.
  1. Once the sensor is at the correct height, carefully tighten the retaining nuts to secure the sensor in place. The 18mm “Standard” and 12mm “Mini” sensors include retaining nuts made of plastic so don’t over-tighten them, but ensure the sensor doesn’t wiggle inside of the mount. The 8mm “Micro” sensors include metal nuts with ridges on them, these ridges are designed to dig into the sensor mount to keep it secure. The more secure the sensor is inside the mount, the more accurate it will be when reading the bed. You can use blue Loctite or similar to keep the retaining nuts from loosening over time if desired.
  2. When routing the sensor cable, it should be secured as seen in the picture below. Leave a loop of cable so that the strain relief of the sensor does not move with the motion of the printer. If not mounted as shown, the cable can break with repetitive motion due to creating a strain point on the cable.

Zip Tie/Wire Strain Notes

Do NOT over-tighten the zip ties as you can damage your printer wiring and/or the EZABL™ Pro sensor wire. Damaged wires due to excessive zip tie force and/or improper strain relief are not covered under warranty. See the above picture for proper cable routing.

Firmware Setup #


We support over 25 different printer models and all are listed on the Unified Firmware page.

  • Download the latest Unified Firmware Package for your machine from uf2.th3dstudio.com and extract all the files to a folder on your computer.
  • Follow the directions at the top of the Configuration.h file and on the firmware download page for your machine.
    • Be sure to follow each step and make sure you enable an EZABL probe mount option for the mount you are using on your machine.
  • Set theEZABL_PROBE_EDGEsetting to 45-50mm for larger printer beds (300mm+ size beds) and 15-35mm for smaller printer beds.
    • Adjust the probe edge so that it is not probing over any bed clips or screws. This will skew the reading.
  • We recommend using an EZABL_POINTS setting of 3 (this is the default) to start with and most people use this value on beds up to 300×300. Larger beds should use 5.
  • After flashing the firmware, be sure to reset your printer’s EEPROM by either going toConfiguration > Reset EEPROMor you can reset it via Gcode by sending a M502 followed by a M500. This will wipe the EEPROM and put the firmware defaults in. Failure to do this step will result in erratic printer behavior.

Note: If you have a printer that needs a bootloader this must be flashed before you can load any firmware on the machine. Most printers with a 1284p CPU will need their bootloader flashed. You can follow our bootloader flashing guide by visiting Bootloader.TH3DStudio.com

Note: The EZABL™ Probe mount STL files are included in the Unified STL Pack for every model and probe mount variation that we support.

Adding the EZABL™ Pro Kit to a Custom Marlin Setup

For those who wish to use stock Marlin instead of our firmware, setup Marlin first as if you did not have a probe, then follow our Marlin setup guide here: EZABL Firmware Setup for “Vanilla” Marlin

Custom Probe Mount Setup

If you have a custom probe mount, you will need to measure the distance on X and Y that the center tip of the probe is from the tip of the nozzle. Those will then be entered into the custom probe section in the firmware. This is in the “Custom Probe Mount Settings” section and there is a visual layout in the firmware showing an example.

Sensor/Endstop Test #

The next step you want to do is to check if the endstop is properly being recognized by your board.

Make sure you have your Z endstop wire connected to our EZABL™ Pro Control Board.


  1. Start by moving the Z up until the light on the sensor and the Status LED on the EZABL™ Pro Control Board turn off.
  2. Next, connect to your printer over your preferred slicer (or Octoprint) and issue an M119 and see if the Z_min is showing TRIGGERED or open.
  3. If it shows open, place your finger or an object under the sensor so the light comes ON and then issue M119 again. If it shows TRIGGERED then proceed to set your sensor sensitivity.
    • If it does not, then move the “EZ Switch” on the EZABL™ Pro Control Board and re-run the M119 test. If the switch is in the up position, then move it down. If it is in the down position, then move it up.

Note: We now have additional information about using the M119 command for sensor testing. Please see this article for more details!

Calibrating the Sensor #

The next step is setting the sensor sensitivity.

  • Note: The 8mm sensor (EZABL™ Pro Micro) does not require calibration. This section applies to only the standard 18mm and 12mm “Mini” sensors. If you have an 8mm “Micro” sensor, please skip to the next section to set your Z offset.
  • Note: If you have a heated bed, run this procedure with your bed heated to your normal print temperature. This is to account for the bed changing shape during the heating cycle.
  • If you print at different temperatures depending on the material, then select a temperature in the middle of the highest and lowest temperatures you use.

Status LED Information

  • All sensor sizes have a RED or BLUE LED that lights when the sensor is triggered.
  • 18mm Size – Has 2 LEDs, a GREEN LED that lights to indicate power and shuts off when the RED LED lights (triggered).
  • 18mm Pro-T Size – ONLY has the RED or BLUE LED (triggered) and no green power led.
  • 12mm (Mini) Size – ONLY has the RED LED (triggered) and no green power led.
  • 8mm (Micro) Size – ONLY has the RED or BLUE LED (triggered) and no green power led.
  1. Manually move the Z-axis with the printer’s LCD or your Computer/Pi until the nozzle is on the bed, then move the Z up 2mm for the 18mm sensor size and 1mm for the 12mm “Mini” sensor size. Your sensors triggered LED may or may not be on at this point.
  • This will put the nozzle 2mm (18mm sensor) or 1mm (12mm Mini/8mm Micro sensor) above the bed, which means the sensor will be 4mm (18mm sensor) or 2mm (Mini/Micro sensor) above the bed if you followed our mounting instructions from earlier.

NOTE: The adjustment screw is on the SIDE of the sensor and gold/brass colored on the EZABL Pro models. Some mounts may cover it up. If this is the case, hold the sensor in position while calibrating it and then secure the sensor with the included nuts after calibrating. If you have the “Pro-T” model then the adjustment screw is on the top of the sensor.

Adjustment screw location for the EZABL Pro sensor. If you have the Pro-T sensor model it will be on the top-side of the sensor instead of the middle as shown above.
  1. If you have an AC bed turn the heat off now. If you have a direct drive printer disable steppers as well to make sure E is off. This mitigates any potential EMI from the bed/extruder motor.
  2. Now turn the adjustment screw clockwise slowly until the sensor’sRED LED turns onIf the sensor is already on, turn the screw counter-clockwise until theRED LEDturns off, then turn the screw clockwise slowly until it turns back on.
    • Make sure the RED LED stays on when you remove your screwdriver AND move your hand away from the sensor. If it shuts off or flickers when you do this, turn it just a hair clockwise and move the screwdriver and your hand out of the way again. Repeat the clockwise adjustment until the RED LED stays on when you remove your screwdriver and hand from the sensor.

Additional notes: If you are having issues getting the LED to stay on check the grounding on your machine, visit our Help Center on grounding checks and how to perform them.

Do NOT change the sensitivity if you are getting different heights between prints due to temperature changes. This should be handled by the Z Offset/BabyStepping the Z height. Under normal conditions at most, you should only have to occasionally Babystep small amounts. If you are getting more than that please contact our support to go through more advanced troubleshooting steps. Large babystep changes are usually related to a physical machine issue if M48 is returning a consistent reading under 0.01mm.

Setting your Z Offset #

Now that you have the sensor installed and calibrated, you need to set your Z Offset. This is the distance the printer needs to move the head down to place it on the bed after the sensor triggers.

We HIGHLY recommend you watch the video as it is much easier to see what to do. Here are videos on how to set the Z Offset and tune it:
1. EZABL EZTips – Setting your Initial Z Offset – YouTube
2. EZABL EZTips – Getting the Perfect Z Offset – YouTube

  1. Heat the bed to your normal print temp and do a G28 (Auto-Home) to home the sensor. Your EZABL™ Pro sensor should be in the middle of the bed. Let it sit there for 1 minute after the bed has reached its target print temperature. After homing the Z will show 5mm. This is NOT included in the ZOffset. Move Z down 5mm before proceeding.
  2. Grab a sheet of standard paper and then move the nozzle down by 0.1mm until it just grabs the paper. Once you do that, look at your printer LCD and note the number that the Z shows. This will be a negative number. That is what your Z Offset is.
  3. Enter that number in the ZOffset section using your printer LCD, look forZ Offset/Babystep. This is located underMenu > Configuration > Z Offset/Babystepon most printers. Make sure you store your Z Offset by going toMenu > Configuration > Store Settings. If you do not store your memory, the Z offset will be forgotten when you restart the printer.
  4. Now do another G28 (auto-home) command. The Z should show 5mm still, but if you notice it will actually be 5mm this time, as the offset is considered when homing Z. You can now move the nozzle down 5mm and it should be grabbing the paper.
    • If it is too high or too low, you can further fine-tune your Z Offset by increasing or decreasing that number. We recommend using the “babystepping” feature below to fine-tune on your first print.
  5. While printing, if you are getting it starting too high or too low, press the printer’s menu button 2 times while printing and it will bring up the “Z Offset/Babystep” menu. You can then turn the knob left to bring the nozzle closer to the bed or right to move it further away, this happens in real-time.
    • It is NORMAL to have to babystep a little, especially when changing bed temps. If the resulting 1st layer is level after adjusting the 1st layer height, then the probe is working correctly. If you notice that you ALWAYS have to babystep a certain amount every print then add that to the Z offset. Let’s say you have to babystep -0.2mm and your offset is -2.0. You can change your offset to -2.2mm and store it.

Updating your Slicer #

Update your 1st Layer settings

To get the best 1st layer and adhesion we recommend the following settings:

  • 150% 1st layer width
  • 0.3mm 1st layer height
  • Print SLOW 25-30% speed or 20mm/s
  • Use a skirt set 2-3mm from the part with 2-3 outlines. Use this to adjust/check the leveling result.
  • Use the Babystepping feature mentioned on the previous page to live adjust your Z height.

DO NOT TURN ON ANY SETTINGS IN YOUR SLICER TO MAKE THE HOME POSITION THE CENTER OF THE BED. Your X0 Y0 position is still the same as it was before the upgrade.

Update your starting Gcode

We include sample starting Gcode that you can use in your slicer. This is included with all versions of our Unified Firmware packages.

  1. Open the “EZABL Starting Gcode V3.txt” file located in the Installation Guides folder.
    1. You can also get the starting code here: EZABL Bed Leveling Starting Gcode
  2. Copy the entire file contents and paste it into the starting code/scripts section of your slicer.

Additional notes: The new gcode will have a 10 second wait for heaters to recover after probing. If 10 seconds is not enough to let your heaters recover, change the S10 in the starting code above to however many seconds you want to wait for the heaters to recover.

Get into the habit of leaving your sensor homed BEFORE you start a print this will ensure that the bed is in the same state as when the sensor was calibrated. Your bed will warp/flex during each heating cycle and this minimizes getting an inaccurate mesh when the sensor takes its readings.

You can now run your first print!

Slice up your favorite test file (ours is the 3D Benchy) and print! Make sure to check the skirt and use the Babystepping feature to fine-tune your first layer. If you made any adjustments be sure to store them using Configuration >Store Settings.

Installation Finished! #

Congratulations! You have installed your EZABL™ Pro sensor kit! Enjoy the benefits of having Automatic Bed Leveling on your printer!

Final Notes

  • Make sure you are only using Gcode that was sliced after you installed the kit so that the starting code is present. If it is not then the system will not work correctly
  • Join our communities! Check them out at Community.TH3DStudio.com
  • Make sure your machine is mechanically sound in terms of your belts, leadscrews, wheels (if any), and hotend mount
  • Look up “The Edge of Tech” as they have some great assembly/troubleshooting guides for your 3D printer.
  • Be sure to check the sensor nuts from time to time to make sure they are not “walking” loose. If they are you can secure them with some Loctite Blue thread locker to make sure they are staying put.
  • Most issues that come up are machine-related and not issues with the kits themselves. Be sure to rule out machine issues and check our Help Center before contacting support.
  • If you should have issues with your EZABL™ kit, first visit our Help Center at Support.TH3DStudio.com. This is where we document all known issues with the machines these kits are used on. If you cannot find a solution to your issue you can reach technical support at ContactUs.TH3DStudio.com

OctoPrint/EZPi Notes and Tips

For those of you using OctoPrint/EZPi we highly recommend installing/using the Marlin EEPROM plugin (our version).
This allows you to set your offset from your web browser instead of the display. This is MUCH quicker and saves it to EEPROM automatically. This is the plugin we use on all our machines.

Plugin Details: https://plugins.octoprint.org/plugins/eeprom_marlin/
This plugin is pre-installed on the EZPi kits that we sell.

Disconnecting the Sensor Connector

When disconnecting the EZABL Pro sensor wiring, you must press the locking tab to release the plug from the EZABL Pro Board. With the locking tab pressed, use your other fingers to grasp the sides of the plug and pull out.

Do NOT use the wires to pull the plug out of the socket. Do NOT try to remove the plug from the socket without first pressing the locking tab down to release the tab.

The picture below shows where the locking tab is. If wires are pulled out of the connector due to misuse, this is not covered under warranty. All connectors are checked before shipment to ensure they are fully crimped.

By purchasing and installing this kit you agree to the below terms and the terms of service at: https://www.TH3DStudio.com/terms/

  • There are many things you can do to your printer by installing this upgrade kit or any other modification.
  • You are assuming all risks associated with this modification.
  • You understand that this and/or any modifications to your printer can and/or may void your manufacturer warranty (if any).

TH3D Studio LLC is not to be held liable for any damage to your printer, home, person, or anything else due to issues that may arise from improper installation or failure of this kit.

Firmware Setup and Support #

Support for your printer using Unified Firmware is included free with the purchase of the kit. TH3D supports covers features listed on the Unified Firmware page. If you need a more advanced configuration in a case where you have a custom machine or swapped a board on a standard machine, this may or may not be included depending on how much time is required. This is handled on a case-by-case basis.

If you need help with a custom machine that runs Marlin please contact us here ContactUs.TH3DStudio.com

Appendix #

Sensor wire incorrect routing example:

Was this article helpful?