Introduction: A Simple Stand for an Acoustic Levitator MiniLev

About: I’m a lifelong maker. I became involved with the maker movement because of my children. I was looking for a way to supplement what they were doing in school with some hands-on activity.

This project would not be possible with the amazing project that Dr. Asier Marzo created.

Like all good projects, this one started out simple and grew as time went on. After reading Dr. Marzo intractable and realizing that there were a couple of old HC-SRO4's laying around left over from a robotics project, we decided to build one.

Several things were obvious looking at the pictures of the dual transducer design (MiniLev) and reading articles. First, if the transducers are held parallel to each other, you have a better chance of creating a consistent standing wave. Second, the distance between the transducer needs to be adjustable, while holding the transducers parallel. There was a scrap piece of 8020 on the desk being used as a paperweight. A half hour with Fusion 360, a couple of hours printing the parts, a little back-of-the-envelope math, and we were in business. The original test was done with the extrusion held in a vice on the desk. It met the first and second design criteria and produced really good results.

You hit that time when you should tear a project down and move on to the next; that didn't happen. It was too much fun to mess with, and the envelope was replaced by a notebook. However we did need the vice back, so grabbed a couple more scrap pieces, cut them down and made a base. To clean up the electronics and make the design the portable (think middle school science fair), we created a platform that clipped to the extrusions in the base. This gave us design constraints number three and four. Constraint number five came when we were asked build one for the child of a friend of ours. It needed to be simple to assemble and disassemble.

Step 1: Assemble the Frame - Pick Your Method

There are three approaches to construct the frame.

  • Order everything cut and tapped
  • Cut and Tapp the extrusions your self
  • 3D print facsimiles of the extrusions

All three methods will require extrusion end fasteners. The design calls for two but it never hurts to have extras around. They can be purchase from:

8020 - Standard End Fastener, 1/4-20 (

Tnutz - (EF-010-1/4-20) 1/4-20 Blank End Fastener Assembly (

Also needed is a 5/32 hex wrench. (

All the extrusion used in this project are 8020 series 10. The design we used calls for three cut and tapped pieces. All tappings are 1/4-20.

  • A six inch piece with a hole drilled in the center of the beam
  • A six inch piece with a hole drilled 0.5in from one end of the beam and the same end of the beam tapped
  • A nine inch piece on tapped on one end.

If using the 3D printed options, the holes and tappings are done.

Step 2: Order Everything Cut and Tapped

The easiest way to build the frame is to order everything directly from 8020. Surprisingly for us this also had the longest lead time. It also produced the nicest looking results. The quality of the cutting, tapping and material was impeccable.

We ordered:

1 x 6 in tapped on one end, hole 0.5 in hole on same end as tapp - Four Open T-Slots (

1 x 6 in hole in center (3 in) - Single Open T-Slot (

1 x 9 in tapped on one end - Two Opposite Open T-Slots (

2 x Standard End Fastener, 1/4-20 1.50 (

6 x 1/4-20 Slide-in Economy T-Nut - Centered Thread(

6 x 1/4-20 x .500" Flanged Button Head Socket Cap Screw (FBHSCS) (

Step 3: Cut and Tapp the Extrusions Your Self

Ok, cutting and tapping the extrusions is the cheapest and quickest way to go. It took us about 15 minutes to make the first stand, and about half that time was spent setting up the saw. This topic probably deserves its own instructable. ( Which can be found at: Aluminum Extrusions. ) It is also dangerous. It should not be undertaken unless you have a clear idea of what you are doing. Wear protective equipment, especially eye protection.

We cut aluminum extrusions using a 10 inch miter saw with an aluminum cutting blade. ( The saw is only used for cutting aluminum extrusions.

The cutting process is straight forward. Take the extrusion that you want to cut and measure the length of your piece. Put a mark on the extrusion. With a speed square or a square make a cut line on the extrusion. Measure your line again. Place the extrusion on the saw bed against the guard. With your hand OFF the trigger bring the blade down to the extrusion and line up the outside of widest tooth on the blade with your cut line. When you are happy, clamp both sides of the extrusion. Again, with your hand OFF the trigger bring the blade down to the extrusion and check that nothing shifted when the work was clamped. If you are happy, plug the saw in. Now with your hand on the trigger, make your cut. Unplug the saw. Unclamp the work and measure it. Repeat this process for the other two pieces.

The next step is to drill the access holes in two of the 6in aluminum pieces. The first hole need to placed 1/2 inch from the end of one of six inch pieces. The second six inch piece needs to have a hole drilled in the center, at the three inch mark.

[A quick tip, 8020 makes a drill jig ( ) that makes drilling the holes quick and easy, even with a hand drill. If you do not use this guide or have access to a drill press, drilling the holes is difficult.]

The last step is tapping the ends of the nine inch pice and the six inch pice with the hole 1/2 inch from one side. A 1/2-20 tap is used. ( The nine inch piece can be tapped at either end. The six inch piece with the hole 1/2 inch from one end must be tapped on the same end as the 1/2 inch hole is on.

Step 4: 3D Print Facsimiles of the Extrusions

Go to Thingiverse and download the STL file for the smooth beams. ( ) Use the beam that is 6in in length. Print three copies. The ends of the beam at taped for a 1/4-20 fastener. The 1/4-20 pan head screw is a perfect choice because it requires no t-nut. If you would like to use a longer beam than six inches for the vertical member, multiple lengths can be found here:

The beam has holes positioned at 0.5in from both ends as well as in the center (3in.) The holes are large enough for a standard phillips head screwdriver.

Step 5: The Transducer Mounts

To make the transducer mounts first go to Thingiverse and download the STL files. ( Print two copies of the part. Print one copy of the transducer removal tool.

While the parts are printing take the two HC-SR04 modules and unsolder the transducers marked with the T.

If you have have obtained male-female jumpers cables ( ) remove the plastic ends from the female side. Open up the metal connector so that if fits over the ends of large leads on the transducer. Solder the leads to the transducer pins.

After the mounts are finished printing, clean away the flashing on the top and bottom of the transducer hole in the brackets. If there are any high spots in the hole remover them as well. It should be smooth to the touch on the inside of the hole.

Placing the bracket on a hard, stable surface with the face of the bracket down. Gently start pushing the transducer in the back of the bracket. Using the tool, push the transducer down till it is flush with the face of the bracket. Repeat with the other bracket.

Step 6: The Electronics Platform

There are two options for wiring the electronics platform depending on whether a BUCK converter is being used or not. Select and print the one that is most appropriate for your project.

Step 7: Assembly

Lay the three pieces out on table.

Take the nine inch piece (or one of the 3D-printed six inch pieces) and insert a joiner into the tapped hole at one end.

Insert the joined end into the six inch beam that has a hole 1/2 inch from the end. The bolt on the joiner should be visible through the hole. Use a hex key to lighting the bolt.

Insert the second joiner into the tapped hole on the end of the beam with the 1/2 inch hole from the end. Position the joiner so that it is perpendicular to the nine inch beam. Slide the beam with the hole in the center over the joiner and position the hole so that the bolt is visible in the hole. Tighten the bolt

Slide the transducer mounting brackets into the top of the nine inch beam. Tighten the bottom bracket.

Slide the electronics platform onto the top of the back leg.

Step 8: Wiring

The wiring is the same as listed in step 26 of

On of list the things that we used that vastly simplified the wiring, was WAGO 222 five position connector and this bracket for an 8020 series 10 beam. You will need to print two.

Step 9: Loading the Software

The directions for programming the micro controller are found in step 26 of

There are also several other projects that are referenced in the comments that are worth a look.

Step 10: Use

Turn it on and have fun. You can reference the original instructable to pick up trouble-shooting information.

Step 11: The Next Steps

This project lends itself to modifications. To get you started here are some alternative designs for sound stages.

The dish is interesting because you can get several pieces of styrofoam to levitate at the same level.

Step 12: Resources

Tool List

◎ 10 Series Access Hole Drill Jig for 1010 Profile 20.80

Access Hole Drill - .201 x 2.30" 4.00

Standard End Fastener, 1/4-20 1.50

IRWIN HANSON 1/4" - 20 NC Tap and 13/64" Drill Bit Set, 80230 8.29

IRWIN Tools T-Handle 1/4-Inch Capacity Tap Wrench

Oshlun SBNF-100100 10-Inch 100 Tooth TCG Saw Blade with 5/8-Inch Arbor for Aluminum and Non Ferrous Metals 45.97

3D printer

1/2-20 hand tap

8020 series 10 drill guide Drill for access hole

Way to cut 8020 series aluminum profile

Raw materials

1.00” X 1.00” T-Slotted Profile - Four Open T-Slots

1.00” X 1.00” T-Slotted Profile - Single Open T-Slot

1.00” X 1.00” T-Slotted Profile - Two Opposite Open T-Slots


1/4-20 Slide-in Economy T-Nut - Centered Thread 0.21

1/4-20 x .500" Flanged Button Head Socket Cap Screw (FBHSCS) 0.30