Introduction: 3D Printer Bed Leveling Assistance Tool

Hello everyone and welcome to my fifth instructable!

A correctly leveled 3D printer bed is essential to ensure successful and accurate prints.

There are two main ways to get a well calibrated print plate: auto-level systems or manual leveling.

My printer does not have an implemented auto-level and, for various reasons, I do not feel the need to have it. So I always go for manual bed leveling.

The most common way to do it is to move a piece of paper under the nozzle and adjust bed height until you "feel" the correct amount of friction. As you can imagine, the results are quite imprecise, especially if you are a new user. The use of a feeler gauge blade certainly makes it more precise but there is always the "touch sensitivity" variable.

That is why I thought to build a tool to assist me in this important operation. The concept is very simple: a LED circuit that uses, as a switch, the touch of the nozzle on a known thickness element (a feeler gauge blade).

This simple tool will give you exact and repeatable results.

Step 1: Materials and Tools


  • 3V coin cell battery
  • LED
  • Very thin and flexible wire
  • Crocodile clip
  • Flat magnet
  • Plastic bottle cap
  • Cigarette filter
  • Double sided adhesive tape
  • Glue
  • Heat shrinking tube or electrical tape


  • Feeler gauge with removable blades
  • Cutter knife
  • Scissors
  • Soldering iron
  • Soldering tin

Step 2: Prepare the Coin Cell Holder

Usually plastic bottle caps have a raised inner edge in which your coin cell battery (20mm diameter) should fit perfectly.

  1. With a cutter knife, remove the outer part of the cap and keep only this inner ring
  2. Adjust the edges with scissors or a file
  3. Cut a circle of double sided adhesive tape which fits inside the cap
  4. Punch a hole in the cap with the safety pin, right next to the center

Step 3: Prepare the LED Holder

  1. "Pierce" the LED legs through the cigarette filter
  2. Make a cut in the filter for about a third of its lenght, aligned to the shorter leg (negative) of the LED
  3. Bend negative leg 90 degrees through this cut
  4. Optional step: wrap the filter with electrical tape to make it more durable (make a cut to bypass the leg)

Step 4: Assemble the "Main Body"

  1. If there is, remove the protective film from the adhesive tape
  2. Insert the longer leg (positive) into the cap hole
  3. Glue the filter to the top of the cap
  4. Bend positive leg 90 degrees under it (if necessary, adjust its lenght)
  5. Insert the coin cell battery in the cap, positive side up and press to stick it

Step 5: Solder the Wire

  1. Cut a piece of wire and strip its end. The wire should be very thin and flexible not to lift the feeler gauge blade
  2. Solder one end to the bended negative leg of the LED
  3. Insulate soldered wire with a piece of heat shrinking tube
  4. Remove insulation cover from crocodile clip and slide it on the wire
  5. Solder the other end of the wire to the crocodile clip
  6. Place the insulation again

Step 6: Assemble the Tool

  1. Remove the blade of the thickness you want to use from the feeler gauge (I use a 0,05mm blade)
  2. Postion the flat magnet on its end (the magnet allows you to change different thickness blades)
  3. Place the "main body" on it
  4. Close the circuit to try it

Step 7: How to Use It

Your tool is ready!

I suggest you to wipe the nozzle with a brass brush to be sure you have no plastic insulating the tip.

  1. Connect the crocodile clip to a metal part of the printer next to the nozzle (could be the base of the extruder, the barrel, a screw, etc.)
  2. Now, level the print bed the same way you do with paper:
  • Move your extruder to a corner and position the blade under the nozzle
  • Adjust the screw until the LED will light up indicating that the tip of the nozzle is touching the feeler gauge blade
  • Repeat the process in the other corners until you find the perfect calibration
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