Finally!! Test your ABL Probe accuracy in 3 minutes!

Please like this model if you find it useful.  A few likes goes a long way so I can make more.  Thanks :)

Any of the following sound like you?

1. z-offset changes every print!
2. Probe does not seem to work
3. First layer is terrible but it was working great just before
4. My mesh is not right
5. Need to prove to supplier probe is faulty
6. etc…

Note: This does not actually print anything it just moves the printer head around and activates and tests the probe to give you back a result.

This only works with Marlin based firmware.  If you don't get a gcode result back then your version of Marlin does not yet support the probe test.  Tested on Professional firmware from Mriscoc - let me know if it works on std creality firmware please which is an older Marlin version.

One of the causes of these issues listed above is when using a probe is a faulty or inaccurate probe reading.  This gcode tests your probe by taking multiple measurements and then giving you back a min, max, mean, range and standard deviation.  It also incorporates some random movement and does the entire test with the bed at 60c and Nozzle at 200c to replicate common printing conditions.

The closer in value your readings are the more consistent your probe is and that eliminates one cause of issues with the first layer and gives you confidence your probe is at least giving back consistent results.

What you need to do:

1. Works best with a terminal so you can see the detailed results of the test you run on your printer
   • Octoprint (has built in terminal where you can see detailed results)
   • Pronterface or similar
   • Worst case the standard deviation of the test is shown on the printer screen once the test ends 

• Download the gcode
• Open the gcode file with notepad and un-comment the line that starts with M48 (remove the ; symbol from start of line)
• Send the file to the printer (or all of them if you want datapoints not just from center of bed)
  • Standard one that works in middle of bed
  • Same as std but front left (only to use if you are curious and think probe is not working in certain areas)
  • Same as std but back right (only to use if you are curious and think probe is not working in certain areas)
• Via the terminal look at the results, once its done it will tell you the min, max, range, std dev, etc…

Each file takes 3mins or so to run.

That's it!  Check the screen shots they show you useful information so you can do this right.

Note: For Octoprint I recommend turn off temp and processing messages as then its easy to see the results.  Check the screenshots out and you will see one showing you what to do.

Interpreting the results:

My worst std deviation result was 0.003 which for me was a range of .01 between the max and min result of the probe.  The probe has a .04~ +/- accuracy so that seems to be well within spec of my probes claimed accuracy.    

Please add more results to comments so people can compare.  Range and standard deviation are most relevant.