Hydrophobic Drumpad, for MaKey MaKey
For more projects and a summary follow up from our January build night, please see this thread!
This is a pretty simple project, and you don't even have to have a laser cutter like we used. If you have a printer and a pair of scissors, you can get this project accomplished for around 20 dollars or so and cheaper if you are resourceful. This is a hydrophobic drum pad, for MaKey MaKey.
This is a project that combines hydrophobic material with pools of shaped water. Hydrophobic means kind of what it sounds like.. something that repels water. Hydrophobic and superhydrophobic surfaces can repel water so well, that you can get what is being called the Moses Effect. Basically, for all the shapes in the above pictures where there is water (or colored water), the surface that the water is sitting on is just regular, untreated acrylic. Everywhere else has been treated with hydrophobic spray, so water will do everything it can to avoid that area.
We use these free standing puddles of water as electrodes to make the MaKey MaKey act as a keyboard, which in turn controls a music program. This Instructables is for a drum pad made out of shaped and free standing water puddles. You can splash the puddles and they still retain their shape.
The MaKey MaKey is an electronic inventor's kit for kids, older kids, and adult kids. It's a great way to get into electronics. Out of the box, it uses a simple USB connection to a computer and it acts just like a regular keyboard and mouse. To control the MaKey MaKey as a keyboard or mouse, you only have to connect "ground" to one of the buttons on front or pins on the back.
What You'll Need (summary)
This project uses a laser cutter or a regular printer and scissors. This also requires a base material you want to use for the end result and a hydrophobic spray treatment.
This project is intended for use with the MaKey MaKey, a USB device that lets you control how to connect ground to triggers that emulate keyboard and mouse. In this project, we use shaped pools of water to have the MaKey MaKey control a browser based keyboard music program to make sounds.
EDIT: Featured in "Science," and then homepaged! Thanks for all the support and thanks to Instructables editors for checking us out!
Step 1: Materials and Tools Needed
Safety info! For this project, you will need:
Additionally, while the MaKey MaKey is safe around water it is still probably not a good idea to get the actual MaKey board wet. Also, a fairly sound general rule of thumb is to be mindful of electronics and power outlets nearby when playing with water like this.
The main materials you will need:
The main tools you will need:
Additional tools and materials you will need using a laser cutter:
Additional tools and materials you will need without a laser cutter:
Step 2: Option 1: Fire the Laser! (WIP)
We use 3mm acrylic here with a protective adhesive backing. This backing is designed to prevent the acrylic from getting scratched, and it helps to prevent moisture loss when the acrylic is being cut. Without it, the acrylic fogs up.
Lucky for us, because this is perfect for our purposes here. We will take advantage of the adhesive backing to help us make our shapes. We will cut out the top plate, enclosure box, and seat tabs after etching our shapes into the top plate.
Included our designs, but this is very much a WIP. Try tinkering around with the design.
Note: The trapezoid seat tabs need to be adjusted. We made them work with gobs of hot glue, but see if you have a better idea here! There are a lot of different ways to go about doing this. Just edit the SVG file and run with it.
The enclosure box is designed to snap together easily. Simply put the seat tabs into the slots after enclosure box assembly, and then seat the top plate onto the tabs. We used hot glue to seal everything up and secure everything in place. This seemed to work, but you could use acrylic glue to secure everything and a few things would work well to seal everything watertight.
Step 3: Option 2: Hand Tools (WIP)
If you do not have access to a laser cutter, don't fret. Simply go to Option 1 and download the SVG files. Again, you might want to edit the top plate design to use your own image. You might also want to fix our seat tabs or change the wall height.
Once you are ready, print out the designs. You can then transfer the cut designs to your material and use hand tools like a jigsaw to manually cut out the top plate, walls, and seat tabs. For the etch designs (the shapes that you want water to be contained in), simply print these out and cut them carefully with scissors. Try to cut slowly and cleanly.
When you're ready for the hydrophobic treatment steps (see base coat step), simply tape the shapes down flat to the top plate arranged how you want them. The flatter the better, but remember that any tape you use will be removed and this can change the shape of your design. We used double sided tape so that there was no exposed tape. It is OK if you don't get a complete seal here, a little bit of careful elbow grease and love after the treatment dries can remove dried hydrophobic surfaces that creeped into any shapes.
Step 4: Option 3: Jellophobics?! (WIP)
Thanks to Doug at Knox Makers for this idea.
This is an alternative method that doesn't even use hydrophobics. Doug suggested trying this with shaped and molded jello, instead. This greatly reduces the need for most of the steps in this tutorial. If someone tries this out, let us know!
Additionally, as a side note I'm not sure how jello reacts to hydrophobic surfaces but I imagine it looks cool to play with.
Step 5: Remove Excess Backing Carefully (laser cutter step)
If you used a laser cutter and material with adhesive backing, the next step is to remove the excess backing. As you can see in the pics, we only left backing on the shapes that we designed. Be careful not to scratch the acrylic and also be mindful to leave the backing on the shapes in tact.
You might want to have small scissors and a steady hand nearby to cut the excess backing. It can be easier to get the backing off in small sections instead of all at once. To do this, just start lifting from one corner. When it starts to try to give you trouble, just cut through the backing you've already peeled off so that you have smaller sections to peel. Repeat as needed.
Step 6: Base Coat
Follow the instructions for the base coat.
This is where cardboard might come in handy. We set our top plate on cardboard so that we wouldn't accidentally coat the floor with hydrophobics. Our landlord might not have liked that so much.
We used a product that recommends making several base coat passes at about 12" away from the material.
There is specific information on the product we used relating to safety, temperature, shaking the can often, etc.
Step 7: Top Coat
Follow the instructions for the top coat.
The product we used recommended a 30 minute dry time before using the top coat.
We used a product that recommends making several top coat passes at about 12" away from the material with one minute in between passes.
There is specific information on the product we used relating to safety, temperature, shaking the can often, etc.
The product we used recommended a 30 minute dry time before using the material as a hydrophobic surface, with a 12 hour dry time for best results.
Step 8: Inspect the Final Dry Coat
Now that you have dried the final coat, take some time to carefully inspect everything. Do this before removing the backing.
Is there an even coat? Do you see any scratches or particulates? We had to dry ours outside, and a little dirt got kicked up onto everything at one point.
You'll have to use your own judgment here. Try testing things out with water and see how it does. If it rolls around and off like alien water from another planet, we're golden. If it gets stuck in areas, you might want to pat dry the whole area, try to blow off any particulates with very light compressed air, and retreat the material starting with the base coat. A second coat will not hurt anything here.
Step 9: Drill Holes
If everything looks good on the final coat, go ahead and drill out the pilot holes. This method employs a crafter's approach to electronics and does not require an exact science here. We just need the holes to big enough for the wire to be pushed through. You might have to step up your drill size depending on the wire you are using.
We're going to be sealing everything up with hot glue, so it does not need to be a tight fit necessarily.
Step 10: Remove Remaining Backing
Careful, though. Don't get excited here. Be gentle when removing the backing from your shapes.
If you scratch the dried treatment around the shapes when doing this, water will try to escape to the scratch the first chance it gets and it can mess up your design or cause unexpected results.
Anything can be fixed, though. We're makers here, we can do anything! We actually scratched up our design the first time around. No fret, we printed out paper shapes and matched them up, retreated, and everything was fine.
If you do scratch up the surface, it can be fixed and it isn't the end of the world. But it does cost time and more treatment to repair, so best to just be careful here.
Step 11: Inspect Shapes
For smooth acrylic, when we remove the backing from our designs we are looking for just that: smooth acrylic.
If there is any of that telltale foggy dry dust sitting about in our shapes, we will want to carefully remove it.
Anything sharp like a utility knife, screwdriver, etc is a patently bad idea because it will damage the surface very easily.
Instead, just use elbow grease + microfiber + water. That's all you really need. Even a paper towel or shop towel will do fine, but be careful not to scratch things up.
It can be time consuming and potentially boring here, but just go slow and you'll get through it. With luck, you won't have this problem.
If you used a laser cutter and adhesive backing like we used, you probably won't run into this, actually.
But chances are this will at least be a minor step if you used an alternative method.
Again, if you damage the boundary of the shapes and the treated area that needs to stay treated, things might not work like you want them to. Anything can be fixed here, usually with nothing more than a careful retreatment and loving elbow grease.
Step 12: Insert Stripped Wire
Feel free to change up the method, this isn't an exact science.
We used coated, stranded wire that was stripped just enough to poke wire out of the surface of the top plate and bend flat against the shapes.
We fed the wires from underneath the top plate on the surface, and bent the wire over as you can see in the pics.
We're going to seal all this up in the next steps with hot glue, just to make Tesla uncomfortable in his grave.
Step 13: Glue Gun!
We wanted to use stranded wire to make sure there are plenty of points of contact here.
Instead of wire, you could use anything from small bolts to tacks (thanks to Mike at Knox Makers for ideas here).
If you recreate our steps, we used hot glue to secure most of the wire in place and just left a little wire exposed to reduce the chance of people getting bitten by stray and sharp wire. It seems to work like a charm.
We also sealed up the wire holes so that water cannot leak out..
Step 14: More Glue Gun!
..and that includes a hot glue seal on the underside of the top plate!
Protip: Before you go to the trouble of sealing off everything, you might want to go ahead and hook up these electrodes to the MaKey MaKey and make sure everything works right. How fun would it be to seal it all up only to find out something needed to be rewired? Not very, let me tell you.
Step 15: Dive In!
After everything's finished, wire up to the MaKey MaKey again, fill your shapes up with water, and try it out.
So, you might notice that the water only barely holds shape or doesn't like to turn angles very well. You might have a weak coat or product, or you might have scratches and particulates mucking things up. Try a better coat.
We used food dye to add color to each shape, and we were sure to have paper towels and a bowl of water handy for people to clean their hands off with. It can get messy. If you use food dye, warn any unsuspecting participants that the food dye might stain clothes if they aren't careful.
Load up a music program and try it out! If you need to remap the MaKey MaKey to work better with a certain program, you can do that:
v1.2 browser based remapping tool
P2PU course on reprogramming oldschool with an Arduino sketch
Here's a couple of fun browser based programs that use keyboard keys to control music:
Jam With Chrome
Our own custom drum pad on Scratch
Did you make this? Use the "I Made It!" feature in the comments! If you edited the SVG file to decorate the top plate or walls, or if you came up with a better idea for the enclosure box and seat tabs, let us know and we'll edit your design in as samples and alternative methods with full credit to you!
Step 16: Get Your Hydrophobics Badge!
You can download and print our "Fearless Hydrophobe" achievement badge to sew on to other projects or glue magnets on for your fridge!
The .STL files are here. More info and models for bulk badges/magnets are at Thingiverse.
If you try this project alone or as a group workshop, post pics and use the "I Made It!" feature in the comments section!
As always, comment with feedback suggestions and concerns, particularly if you spot ways this Instructable can be improved. Good luck, and I'm here to lend support on this project if you need help.intro_to_hydrophobic_surfaces_badge.stl