The BL Touch is an indispensable tool in 3D printing that ensures your print bed is level to get high-quality prints. However, it can encounter issues where it fails to probe all points. I decided to research some of the leading causes of this problem and their potential solutions.
To fix a BL Touch that is not probing all points, you’ll need to route the BL Touch wires correctly, level the bed manually, tighten the z-axis coupler, and adjust the screw on the top of the probe. Other effective methods include changing the G-Code flavor, editing the firmware settings, and changing the firmware.
This is a basic overview of what you’ll need to do. I will go over each method in detail in this article, so keep reading to find out more.
How to Fix BL Touch Not Probing All Points
Below are some of the main methods of fixing your BL Touch not probing all points.
- Route the BL Touch wires correctly
- Replace damaged BL Touch wires
- Level the bed manually
- Adjust the screw on the top of the probe
- Clean the probe and print bed
- Tighten the Z-axis coupler
- Change the G-Code flavor
- Change the firmware or edit the firmware configurations
1. Route the BL Touch Wires Correctly (Proper Cable Management)
The first way you can fix a BL Touch that is not probing all points is to correctly route all the BL Touch wires and tie them up.
Poor cable management can cause the BL Touch wires to be pinched, bent, or stretched beyond their limits, leading to damage. This will cause it not to function. What you need to do is:
Gather the Following Materials
Cable Ties (Zip Ties): You will need them to bundle and secure the wires. These 8-Inch Zip Ties from Amazon would be perfect for that.
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Wire Cutters: Use them to trim excess wire length after cable management. Having the correct size of wires reduces resistance. I’d recommend this cheap Dowel Micro Wire Cutter from Amazon.
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Power Off the Printer
For safety, turn off the printer and unplug it from the power source.
Properly Bundle and Route the Wires
Next, carefully bundle your BL Touch wires with the other cables from the hot end and zip-tie them all the way to where they go into the mainboard. Ensure you route them in such a way that they don’t bend excessively.
Cut Off the Extra Length of the Zip Ties
Finally, using your wire cutters, cut off the extra length of the zip ties so they don’t get tangled anywhere.
Now, plug in your printer and power it on. Check whether the BL Touch can probe all points without fail. If it doesn’t, you can try another fix.
Here is a video demonstrating how to route your Ender 3 Pro BL Touch wires correctly.
Also, ensure that each BL Touch wire is properly seated and secured in its respective socket in the mainboard.
One user recommended using a zip tie to secure the wire to the body of the BL Touch. This is because the wires get jerked around and lose connection for a split second, causing the problem. He noted that this would fix the issue if the bad wiring hadn’t fried the board.
Another user said that his BL Touch was having issues where it failed to probe on random points when he tried to level the bed. It turns out it was just a loose wire at the BL Touch hotend side. To fix the issue, he used a simple cable tie over the BL Touch head and wire.
Someone recommended routing the BL wiring up and over the front of the machine and into the control board as far away from the rest of the wiring as possible, as shown in the image below. Another user tried this fix, and it worked for them.
2. Replace Damaged BL Touch Wires
Damaged wires can cause the BL Touch to fail to transmit or receive signals, causing inconsistent probing. So, it would be best to examine all of them between the BL Touch and your 3D printer’s mainboard. If any wires show signs of damage, replace them with new ones.
You can go for the BIGTREETECH BL Touch Extension Cables + Mount compatible with Ender 3, Ender 3 Pro, Ender 3 V2, and Ender 5 Pro.
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Here is how you can install the BL Touch wires after replacing them.
One user wanted to know how to fix his BL Touch since it was not sometimes probing all points and crashing. Someone advised him to try replacing the wiring for the BL touch. He added that his wire broke off at the point where it bent regularly.
3. Level the Bed Manually
Sometimes, the bed may not be leveled adequately for the BLTouch to work correctly. Manual bed leveling can help compensate for such inconsistencies. Although the BLTouch is a leveling sensor, you still have to ensure it has a flat and even surface to work with.
This will enable it to probe all points and give out accurate results. Most 3D printing enthusiasts recommend the paper method to help you manually level your 3D printer bed. Check out this video that explains the process of leveling the bed of an Ender 3 V2 Neo.
I wrote an article explaining how you can level your printer bed: How to Level the Ender 3 Bed Properly – Simple Steps.
One user shared a video of how his BL Touch probed 2 points and stopped when leveling the bed. Someone commented that his BL Touch was stopping because it wasn’t triggering at the expected height on the right-hand side.
This was because the bed was not even vaguely level. He advised the user to try to get the bed as level as possible the old manual way before doing a probe. This fix also worked for another user who had the same issue.
Another user with an issue with his BL Touch probing only the first point said that his bed was way out of level. One or two corners of his bed were much lower than the center.
He advised anyone with a similar issue to check the bed level manually by following this procedure:
- Home the Z
- Move the print head manually to one corner
- Set the print head down until the coordinates state Z 0.0
- Check the gap
- Repeat for all the corners until you achieve a consistent and uniform gap across the entire bed.
A user said they always got errors while probing the bed because it would just stop. It turned out that his bed was so out of whack that it was beyond the ABL’s ability to compensate for it.
ABL (Auto Bed Leveling) sensors like the BL Touch can only compensate for a +/- 2mm difference. The solution is to use the old paper method to level as much as you can and then try to probe again.
4. Adjust the Black Set Screw on Top of the Probe
A potential solution to a dysfunctional probe is adjusting the black set screw on the top of the BL Touch. This set screw is magnetic to hold the probing pin (which also has a magnet at the top) in place and draw it back into the probe after it has been deployed.
If the screw is too tight, the magnetic force can be overwhelming, causing the pin to fail to deploy. In that case, you can loosen it a bit. On the other hand, if it is too loose, tighten it to increase the attraction and make it easier to draw the probing pin back up after it has been deployed.
This ensures that the BLTouch consistently triggers at the right moment during probing, improving the probing process’s accuracy.
One user said to solve his BL Touch probing issue, he turned the core screw on the top of the BL Touch 180 degrees tighter. This helped to increase the sensitivity of the pin. He also re-tightened the BL Touch to the arm of his fan shroud because it had become slightly loose.
Another user whose BL Touch failed when bed leveling for no reason said they played with the screw on the top of the BL Touch, which fixed the issue.
A user whose BL Touch started failing while probing while running the Smith3d firmware was told to adjust the black screw at the top of the BL Touch. In addition, he was advised only to do half turns at the max at a time.
BLTouch just started failing during probing. Running Smith3d firmware with mostly no issues then suddenly it fails when doing 5×5. I was using the slow 5×5 but flashed to see if fast 5×5 made a difference and it did not. I’ve check all connections and the cabling is fine. What’s wrong?fix?
You can use this Hex Screw Driver Set on Amazon to adjust the set screw on the BL Touch.
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5. Clean the Probe and Print Bed
Clean the BL Touch probe and the print bed gently with Isopropyl Alcohol and a lint-free cloth to remove dust, dirt, and other debris. Although uncommon, dust, dirt, or other residue might hinder your probe from functioning correctly.
You can use this Amazon Basics 99% Isopropyl Alcohol.
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Most people combine this method with other fixes so that it can successfully fix the problem. For instance, a user whose BL Touch started failing while probing said they had first to reconfigure the Z offset.
After that, they removed the dust that might have been causing the issue and ran the auto-level option repeatedly until it started working again.
Another user whose BL Touch failed to probe on random points said that they unscrewed the set screw on top of the BL Touch and cleaned the inside with cable cleaner spray. Then, they let it dry and assembled it back together. This fixed the issue.
6. Tighten the Z-Axis Coupler
Another way to fix your BL Touch if it doesn’t probe all points is to tighten the Z-axis coupler. If the coupler connecting the Z-axis lead screw to the stepper motor shaft is loose, it can cause inconsistent Z-axis movements. This can potentially make the BL Touch skip some points while probing.
To fix this, access the coupler, and tighten the top and bottom screws with an Allen key until it doesn’t wobble. This will help to stabilize the Z-axis movement during probing, reducing the chances of failure.
Here is the ELEAD Allen Key Set you can find on Amazon, which will help you.
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This video shows how you can tighten the two screws on the Z-axis coupler of an Artillery Sidewinder X1.
One user wanted help fixing his BL Touch that was only probing the first point and then stopping after trying both the 5-point- and 3-point grid. Another user said a potential solution would be to check the Z-axis coupler and ensure it wasn’t loose.
You need to hold the motor and try moving the rod manually. If you can’t, the Z–axis coupler was tight enough. However, if you can, you’ll need to tighten it further.
7. Change the G-Code Flavor
To ensure that a BL Touch command such as probing is executed well, the G-Code flavor has to be consistent between the slicing software and the printer’s firmware. So, if the G-Code flavor in your slicer does not match the flavor expected by your printer, change it.
This will help to prevent the BL Touch from misinterpreting specific commands, such as those that tell it to probe different points on the print bed.
Here is how you can change the G-Code flavor to Marlin in Cura:
- Launch Cura and go to “Settings”, and then “Configure setting visibility”.
- From the window that pops up, go to “Printers”, and then click the “Machine Settings” button.
- Under the “Printer Settings”, go to “G-Code flavor” and select “Marlin” if it wasn’t the default.
One user said that his Ender 3 started failing his prints one day until he discovered that the flavor went from Marlin to Marlin Volumetric without him changing anything. He had to revert to Marlin to fix the issue.
8. Update the Firmware or Change the Firmware Configurations
If all the above options fail to fix your BL Touch issues, the last resort is to update your firmware or change the firmware configurations.
Changing to a more recent firmware version improves compatibility and ensures the printer communicates effectively with the BL Touch. This will improve the reliability in probing and leveling, reducing the chances of failure.
Always get the most recent firmware version since it contains all the latest bug fixes and other relevant updates that improve its functionality. Here is how you can download the latest version of Marlin for an Ender 3 Pro and change the firmware configurations:
- The first step is to check your 3D printer’s mainboard model and the version. You can do it as shown in the video below.
- Next, download Visual Studio Code to edit and compile the new firmware. To do this, go to Visual Studio Code website and hit the “Download for Windows” button.
- Once you’ve downloaded and installed it, open it and click the extensions icon. After that, search for the extension “Auto Build Marlin” and install it.
- Next, go to the Marlin website and download the latest version of the firmware and its Configurations files.
- After that, extract both files to the same folder you saved them.
- Now, go to the Configurations file > Configurations- release – 2. X. > Config > Examples > your 3D printer > your mainboard type > copy all the files.
- Paste the config files back into the Marlin folder.
- Open the Marlin folder in VS Studio Code by going to File > Open Folder > Select the Marlin Folder.
- To make changes to your firmware, make modifications or edit your Configurations.h and Configurations_adv.h files. Search for any setting by typing it in the search bar.
- For example, you can comment out the Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN by adding “ // ”.
- Finally, you can save your changes by clicking CTRL + S and then clicking the “Auto Build” icon on the left side of your screen. From the window that opens, choose the environment that matches the one on your board and click build. This will compile your new firmware.
- Give it a few minutes, and it will generate a file you can transfer to an SD card and install it on your printer.
Check out this video by Ruiraptor that explains how to upload and edit new firmware.
One user said that they had a problem where the BL Touch failed while probing when using Creality’s firmware. His son, who also used the same firmware, said Creality’s firmware was the limiting factor and advised him to change it.
His son downloaded the TH3D firmware for the Ender 3 board (luckily, they had the same), modified it, compiled it, and tried it out, and it worked flawlessly. He then sent him the same firmware he installed and reconnected his BL Touch, which has worked perfectly ever since.
Another user said that they were able to fix their BL Touch not probing all points after commenting out the “USE PROBE AS Z ENDSTOP” line in their firmware.
This is because if this line is uncommented, you must have the black and white wires from your BL Touch connected to the Z Min endstop plug on your board and not connected to the “Probe” plug on the board as many guides online dictate.
A user had a problem with the BL Touch, only probing the first point and stopping after probing the Z-axis. Someone told them to pick the firmware that matches their configurations.
This is because there are a few flavors of the firmware. There are two options for the BL Touch: one where the BL Touch is connected to the Z-endstop and two to the servo.