3D Printer audible bed leveling tool

by jaykoehler, published

3D Printer audible bed leveling tool by jaykoehler May 3, 2013


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The Koehler audible bed leveling tool.

Tired of painful exacting bed leveling? Try this for a quick painless method. All parts are available from your local radio shack for less than 15 dollars.

Use with thing 97151 to get your bed just right.

You will need:

  1. Piezo buzzer 3-20v pn 273-059

  2. Gator clip (large enough to attach to your hotend)

  3. PCB (copper clad board) cut into four pieces

  4. 22 ga wire (8 -12 ft)

  5. 4.7k ohm resistor

  6. power source (9v battery or molex 4 pin for atx power supply connection. I prefer a 9v battery as some ATX power supplies will trip the breaker shutting down your power supply)

  7. power supply connector depending on your preference of power supply. I personally use small gator clips to allow multiple options for power sources.

  8. 4 bulldog clips (if you use a glass bed you already have the ones you need.)


  1. Cut PCB (copper clad board) into four 1”x1” squares.

  2. Solder a length of wire (12”) to the top of each PCB square.

  3. Combine all four wires together and attach to a fifth length of wire (2 – 5 ft).

  4. Solder piezo buzzer to opposite end of fifth wire.

  5. Solder second wire from piezo buzzer to power supply connector.

  6. Cut sixth wire to approximate length of first wire assembly.

  7. Attach gator clip to sixth wire.

  8. Solder 4.7k ohm resistor to opposite end of sixth wire.

  9. Solder opposite end of resistor to second power supply connector. Polarity matters here so test the connection by switching + and – for loudest buzzer sound first. You’ll know when you have it right.

  10. Attach power supply connector to your chosen power supply

  11. Test by touching gator clip to each PCB square.

  12. Attach gator clip to metal section of hotend.

  13. Using bulldog clips, Mount the four PCB squares to the corners of your heat bed. Make sure the PCBs sit flush to the heat bed.

  14. Very important!! Clean the bottom of your hotend tip with a cloth and acetone to remove all filament. Only the lowest part of the tip matters. Do not file or sand the tip of your hotend unless you want to alter it’s performance.

  15. Move your hotend and heatbed to center tip above first PCB square. Adjust your spring retaining nut until the buzzer sounds. Go corner to corner and adjust your leveling springs until your bed is right where you want it. It may take a few times around to get it just right. I find that using this technique gives me an accuracy of 0.004mm. As good as it gets for me in less than 5 min. I recommend doing this with your heatbed at temp. You would be surprised at the difference. Also remember to orient your glass the same way each time. Its all about the details. Enjoy the rest of your day printing rather than fighting your heatbed using mechanic methods.

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what about the thickness of the copper clad ??

Might be able to use Aluminum duct tape in the corners and just leave it there if the solder and tape glue will hold up to the bed heating cycles.

I was trying to think of a way of doing this using the contact of the hot end. I had all sorts of elaborate ideas about self levelling. But this way is much simpler, well done!

A multimeter with a audible continuity detector could also be used.

I would probably also wire the pads in series to reduce the length of copper wire I had to use.
But as I have an aluminum headed hotbed I might just as well just hook up the wire to it :)

I personally use the "a sheet of paper has to have the same friction under the hotend method", but this seems more elegant.

If everyone stuck to the old paper method, we'd be reading books instead using computers. With any luck, someone will automate my tool and save all of us alot of trouble. One small step at a time.

And there are already some work in "progress" for automatic bed leveling, seems like they plan to simply offset the z axis.
(Should cause some minor dimensional distortion if you ask me, but for beds that are mostly level it will be very minor)


thats a good article. guess I'm a year behind so I better get at it. I made a similiar tool for my cnc mill using mach3 . It will automatically home x/y then z till the cutting bit makes contact with the pcb. it will subtract the thickness of the the pcb and set the z height making tool changes easier than without. I have no doubt a program could be written to run prior to printing to repeat what mach3 does times 4 and calculate the exactly position of the corners. Just need a little collaboration as my programming skills lack in this area. Anyone want to assist?

Automatic bed leveling would probably be quite expensive due to all the motors needed.

Coordinate transformation inside firmware on the other hand should be relatively easy.
But would result in steps/stairs even on flat parts.
(very tiny ones as the printer axis resolution is quite good)

It should probably be quite easy to just apply the 4x4 transformation matrix on a sliced g code file as well