I built a fully-featured backpack-mounted powerful motorized solution to your dirty car problems.
Tired of washing your car while tethered to the garden hose?
Did you enjoy watching Ghostbusters? Do you have an old Scuba tank laying around?
One of my biggest pet peeves is having a dirty car, there is nothing worse than showing up to a date or a meeting looking like a slob. Last week, my car was super dirty and i had to do something. I had this old scuba tank and I had a crazy idea; to make a proton-pack style portable car washing apparatus.
I used two scuba tanks, plumbing bits, air blower, a water cannon, a waterproof power drill, 8 mops and some other odds and ends.
I built a 4 stage backpack-gun system for cleaning cars.
- Soapy water gun
- High-speed microfibre spinning flappy hyper brush
- water rinse gun
- Air water removal
Step 1: Plan and Design
My first step was to sit down with a pencil and think about what a car wash needs.
Soap, water, scrubbing, and drying seem to be the core tenants of car washing.
I found a Soap Water Cannon on Amazon, which took care of the soap and got me started on the design. It strongly reminded me of a firehose or the ghost catching guns in Ghostbusters.
I knew that it would need a supply of pressurized water, so I started thinking about ways to have portable water pressure. Since water itself cannot be compressed, water tanks must always have a propellent of some kind. Some use bladders or sprung pistons, but the majority use a gas like air.
I decided to go with a simple air/water tank that uses air pressure to push the water out at the bottom of the tank.
This is the same way aerosol cans work, but they have a short tube inside to ensure the liquid and not the propellant gas is released when the button is pressed.
I knew I wanted a spinning brush and that a drill would be a good way to spin it, but it took a lot of trial and error to make the brush and get it to spin smoothly. At this stage, I had no idea how I was going to attach it all together. I had a feeling it would work out, but I knew it was hopeless to plan without the actual objects in my hands.
Step 2: Finding Your Parts
Safety was a concern. Although the voltage is low, water and electricity are known for their bad relationship. Luckily, the internet provided me with an incredible Waterproof 18V Drill. It had more than enough torque for the application and I knew I wouldn't get shocked. It isn't cheap, but it is a fantastic drill for all kinds of uses.
It took me a bit of shopping to find mops suitable for building the HyperBrush. I tried wool felt, synthetic felt, cotton rope, a poly mop, and eventually settled on this Microfiber Cloth Mop Refill. I used 8 of them. I bought a Cob Web Duster for cleaning my rims and a broomstick to mount all the brushes on.
I had a decommissioned dive tank laying around. it was too old to use for life supporting dives, so I decided to give it a new life as a water tank. These can probably be found at dive shops or garage sales. A brand new tank would work as well, but they cost about $200 USD.
The Air Blower
In order to dry the details of the car quickly, I wanted a powerful air blower. Seeing as there will be compressed air in the tank, I went with a line-fed Whisper Jet Air Gun. It is super sturdy, all metal, and quiet.
I used a 14" length of perforated unistrut, a few unistrut specific fittings, a lot of plumbing bits, and some nuts and bolts. I'll get into the specifics later.
Do not forget your Air Force Style Military Flightsuit Coveralls. They are for your safety.
Step 3: Prepare HyperBrush Shaft
This is one of the trickiest parts, and I made some bad decisions.
In hindsight, I wish i had just used a 3/8" metal rod that could fit directly into the drill. Using the mop pole made it super easy to mount the cob web duster, but super difficult to mount to the actual drill.
What I Actually did:
- Screw the cob web duster onto the mop pole
- Lay the pole on top of all the mops
- Guestimate the desired legnth
- Mark the pole
- Take the cob web duster off the pole
- Cut the pole on the chop saw
- Carefully mark the exact center of the rod end with a center finder
- Gently punch the center
- Find a long(2-3") round drill/driver bit of some kind(I used a 3" Phillips driver)
- Measure the diameter of the bit
- Find a drill bit slightly smaller than the bit (more than snug)
- Drill a 2" deep hole down the length of the pole
- Hammer the bit into the pole
Now you have an extremely long drill-compatible spinning wooden rod with a brush on the end!
This worked for me, but likely depends on how nice your mop pole is.
Step 4: Destroy 8 Mops
This is a fun step. You start with 8 mops and you end up with an awesome car washing hyperbrush.
- Get mops
- Drill your rivets
- Discard all the plastic bits
- Gently wrap ziptie round center, across the existing blue string
- Cut Blue string
- Tighten zip tie slightly
- Thread mop around hyper brush pole
- Tighten ziptie
- Return to step 1. until you have no mops left
Hyper brush is nearly complete!
Step 5: Building the Arm Brace
This thing is quite heavy.
As soon as I finished the HyperBrush and tested it with the drill I realized my wrist was not sturdy enough to single handedly wield a power drill with a long spinning soaking wet brush.
I toyed with some ideas and landed on a both a two handed system and a forearm brace to take some of the weigh off my hand.
I based the brace on a piece of Uni-Strut channel. Uni-strut is a very strong and cheap erector-set like system of securing heavy things. It is often used to keep electrical conduit, plumbing, and AC equipment in its proper place. It is sold in the electrical isle of your local big-box home improvement retailer. In addition to being a very rigid perforated steel beam, it has a lipped channel that accommodates a host of accessories for holding pipes and bolts of varying sizes. Here are some other things it is used for.
I had not yet figured out my plan for mounting the water/soap cannon or the air blower, but I knew there would be some way to mount to the versatile strut.
Mounting the brace to the drill took some trial an error. Luckily, the drill I used had a side handle for extra control with an exposed bolt hole. I was able to simply take apart the handle and put it back together in a way that it captured the strut. For the secondary connection point I used hose clamps to hold the strut tight against the body of the drill.
Hose clamps are one of my favorite fasteners. They are extraordinarily strong, they love irregular shapes, and they can be reused infinitely.
Step 6: Carving the J-shaped Arm Cradle
I found a nice Oak scrap in our bin, so I used it for the J-shaped arm hook.
You will need a lag bolt suitable for the wood shape you end up with. A lag bolt is a very strong type of wood screw that typically requires a lot of pre-drilling.
- Rough out your j-shape with a bandsaw, jigsaw, coping saw, or hacksaw
- Round the edges with a power sander or a file
- Use a Round Over 1/2-Inch Radius Router Bit to round all the remaining corners
- Hand sand the entire thing with increasing grits of sandpaper
- Finish with paste wax or urethane
- Drill a pilot hole in the straight part of the J, sized for your lag bolt
- Attach the J-shaped arm cradle to the brace with a lag bolt.
Now you have a nice smooth hook to help support your super heavy gun.
Step 7: Assembling the Gun
This is the magic of Uni-Strut.
You can just mount things to it, anywhere along it, without drilling any holes. If you make a mistake, you can just move it. Steel K'nex, sort of.
Our blow gun has a hook on top that perfectly accepts a 1/2" bolt. It was mounted to the channel with a special 1/2" Unistrut nut.
Our Water/Soap cannon had no holes, but a nice round body in front. It is mounted with a clamp that is designed to secure round electrical conduit. I carefully drilled a hole in the cannon for a 2" inch 1/4"-20 screw on the rear of the cannon to keep it stable.
There is some assembly footage in the main video, check it out!
Step 8: Prepping the Water/air Tank
I had a few considerations when I was figuring out a tank solution. I wanted a single tank with water and air, where the air could be used as both a propellant for the water and to supply the air gun to help dry the car.
In order to provide garden-hose level pressures, I needed a tank that could sustain pressures of 120 psi, putting any purpose-built backpack sprayers out of the question. I considered using a water-type fire extinguisher which is already very similar to what I wanted, but I would have had limited modification options due to the thin walls. I had a decommissioned scuba tank laying around, and realized it was perfect. It comes with a back pack, it is designed to carry immense pressures, and its thick walls allow for me to drill and tap pipe threads anywhere.
The tank comes with a single specialized valve on top that I didn't want to bother with. I opened the valve all the way to double check that the tank was empty before I began any work. It probably goes without saying that drilling a hole in a full tank of a compressed gas is not a good idea.
I added a mess of features to this tank.
- Pressure gauge
- Air Regulator
- Air Filling Nipple
- Garden Hose Spigot
- A sight glass for determining water level, made out of a piece of vinyl hose running down the side.
Its a lot of work, but it ends up looking great.
The tank is to be filled half way with water then pressurized with 120 psi of air from a bike pump, air compressor, or a real scuba tank. The air presses the water down allowing it to be dispensed at high pressure from the spigot mounted on the bottom of the tank.
What is tapping you ask? Tapping is the process of forming or cutting threads onto the inside of a hole. The tool is called a tap. Tapped holes are usually used for bolts and screws, but special Pipe Taps exist for making manifolds and car wash guns, apparently. Tapping is a joy and really can be the difference between a kluge and a really nice object.
See my Alphaclamps Instructable for some nice tapping action for a threaded rod. To use a tap, you first drill a hole of a size particular to the tap you will be using. All of our plumbing bits are ¼"-18 NPT, a very common small size of National Pipe Thread and the size nearly always used for compressed air. The hole we must drill has a diameter of 7/16"(0.438"in. or 11.11mm), which is much larger than ¼". This is because pipe is sized based on the internal diameter of the pipe, and not the size of the actual fitting. Tapping is somewhat difficult physically and requires finesse if you don't want your tap to snap or your threads to be uneven. It is important to keep the tap very co-axial with the drileld hole and not to go in at an angle. Your seal depends on the quality of the threads.
Step 9: Attach Bucket to Hold HyperBrush
You hyperbrush is long and heavy.
It needs a quiver!
A 5 gallon Bucket is perfect for this. I drilled some holed in the bucket bottom with a spade bit to allow water to drain then drilled a ¼"hole in both the bucket and the scuba tank holder. I used a ¼"-20 Button-head socket screw and a nylon lock nut to secure them together.
Step 10: Fill Your Tank and Wash Your Car!
To prepare the system:
- Get flight suit and rain boots on
- Ensure the tank is drained of air pressure
- Fill scuba tank half way with water through the spigot with air bleed valve open
- Pressurize tank to ~100 PSI with air using an air source, such as a bike pump, air compressor, or another air tank
- Fill water-cannon soap cup with your favorite car washing soap
- Attach all hoses to gun
- Have a friend help you get the 60 lb tank onto your back
- Pick up gun
- Put the HyperBrush in the quiver
You are now ready for a car washing experience unlike any you have ever had.
If a picture speaks a thousand words, a and a video contains a thousand pictures, I can save time by reffering you to the video on the top of the 'ible. Who has time to read a million words?