PROJECT SUMMARY: Take a shop vac, 3D print my custom designed hose adapter, then connect a Rainbow brand power nozzle for cleaning carpets, and voila, you have the ultimate indoor/on-a-budget/carpet-cleaning vacuum!

Our family has a love/hate relationship with vacuums:

As an engineer, I love the cool technology, complicated mechanics, high quality reliable construction, and the more expensive the better (Think of Dyson, Rainbow, and Kirby).
My wife just wants something that works well, lasts longer than a trip around the sun, is easy to clean (itself, bags and what not), and costs less than $300 (Think of uhhhh ...... ummm ....... hmmm ........).

Well, See that's the problem - Nothing fits that description! !!! UNTIL NOW !!!

I present the Rainbow Shop/Home Waterless Super Power HEPA Filtration Vacuum Hybrid Frankenstein Cleaner Thing. Or the RSHSPHFVHFCT. Any marketing gurus that can help me here?

Long story short, we have # vacuums (embarrassed to say how many) and literally they are all horrible, even the Rainbow that donated its power nozzle, three different Dysons, no-name Walmart clearance purchases, and every single one from Goodwill stores (gee, I wonder why someone donated it?).

The Rainbow, being the most recent purchase, was a gamble (used on eBay) that didn't pay off. The primary motor needs to be rebuilt and if I'm taking the time to rebuild a motor it ain't gonna be a vacuum motor. Plus, the water tray is a real pain to deal with. I understand its benefits, but its a hassle to fill and dump. The power nozzle though is REALLY good.

So, as most of my projects usually start, "Hey!, What if I take this thing and combine it with that thing?", I thought of attaching the Rainbow power nozzle to a motor that did work and instantly thought of my shop vac. A little tinkering, some "Wait a minute, how does this thingy mate with that thingy?, Ohhhh thats how.", a few hours modeling in Fusion 360, and about five prototypes, I arrived at a design that only requires one 3D printed part, one purchased part (the power cord), and at least in my case that was it as I already had the other donor items.

But even if you have to purchase all these items, guess what?, that sub $300 vacuum that meets my wifes' requirements is still possible!

Supplies

Dewalt Shop Vac
Rainbow E2 Series Vacuum Power Head (Search for used on eBay)
Power Cord
HEPA Filter (Optional)

TOOLS:

3D Printer
Xacto Knife or Razor Blade
Orange Sticks

Step 1: Design

I use Autodesk's Fusion 360 for 3D modeling and can't recommend it enough for both beginners and well-seasoned professionals.

The image above shows the finished part(s) (there's two of the same part, just flipped over to show all the features) in the Fusion 360 environment.

I've included both the .STL file for those wanting to print this exact model, and also the native Fusion 360 file if anyone wants to modify it.

Step 2: 3D Printing

I use Cura for the slicer software (this software converts a 3D model STL file to a GCODE file that is then sent to a 3D printer to print the model).

Overture brand PLA Professional (or PLA+) is the 3D printing filament I use almost exclusively. For items like this where I want good durability and don't care about the weight I print solid (100% infill). Also, this can be printed in either orientation as shown in the image above, but it requires supports everywhere regardless of orientation. The way the "thread" portion of the part is modeled requires supports along the entire coiled thread path. So clean up of the supports will take a bit of time.

(An "orange stick" works well to pry out the support material.)

Step 3: Modification - Electrical Cord

Grab your Xacto. To adapt the standard power cord to mate with the Rainbow's hose you need to make the same cut on opposing sides as indicated in the first image. The second image is after the cuts were completed. This allows the cord to plug into the Rainbow's hose plug as shown in the last image.

(You may also need to shave off some of that raised surface in the top left of the first image for it to slide into the 3D printed part later.)

Step 4: Disassembly - Dewalt Hose

Remove the hose from the Dewalt vacuum
Remove the black plastic attachment part from the yellow hose by turning it clockwise (if you're looking into the hose). Likened to screw threads, this is "reverse threaded" or "left-hand threaded" so if its not budging, then try rotating it in the opposite direction. There is no glue or anything else holding it together so it should come off easily as long as you're turning it in the proper direction.
Set the hose aside. (Don't misplace it if you want to convert it back to the normal shop vac configuration later.)

Step 5: Gather Supplies

The items I list in the Supplies section are the exact items I used. However, for the Dewalt vacuum, I would assume that many if not all of their similar models use the same hose and attachment. We got this one at a Black Friday sale at Lowes last year for $100.

The Rainbow power head is from a "E-2 Series Gold Model" complete vacuum set that I got off eBay last November for $500. As with the Dewalt, I would assume that other series may use the same attachment style, but I'm not entirely sure. There are tonnes of these old ones on eBay. There are even entire stores that solely deal with old used Rainbows. Search eBay for E-2 or E2 Rainbow Power Nozzle, you'll see there are plenty to choose from. And a deal on a good working condition one is $150-$200.

(So, you can see its possible to get this entire setup for under $300 if you're patient and wait for the sales.)

(Craigslist and similar sites are also good places to find used items.)

Step 6: Assembly #1 (Dewalt Hose Attachment to the Adapter)

Again, this is reverse thread, so you have to turn it anti-clockwise to insert it. Thread it all the way on and snug it up firmly.

Step 7: Assembly #2 (Cord to the Adapter)

The cord has to be installed from one side only and then firmly inserted to become rigid with the adapter.

The cord is not round, but oval. So rotate the cord so the thin section aligns with the open groove of the adapter (First image).
Rotate the cord 90 degrees (direction does not matter). (Second image)
Insert the cord end firmly into the adapter. Do NOT pull on the cord. Push from the plug end. (Last image shows it fully installed.)

Step 8: Assembly #3 (Adapter to the Rainbow Hose)

This step is easy, just insert the adapter onto the Rainbow hose end ensuring the locking tabs on either side are fully engaged.

Step 9: Assembly #3 (New Power Nozzle Assembly to the Dewalt Vacuum

Uh, not sure words are needed here, but I guess I just did anyways.

Step 10: Assembly #4 (Cord Routing)

Route the Dewalt vacuum power cord as shown by the Green Arrow (first image)
Route the Rainbow power nozzle cord as shown by the Purple Arrow (first image)
One overhand knot on the outside of the vacuum handle is sufficient to hold the two cords in place
To keep the two ends together, one (not sure the name of) knot is sufficient (last image)

Step 11: ALL FINISHED

All done! Thanks for taking the time to read through my Instructable. Please send me any questions or comments you might have. I try to answer them all. Stay safe and healthy! Happy 3D Printing and Vacuuming (yay vacuuming!)

Please remember to vote if you like this project. It is entered in the "On a Budget" contest.

Just some wrap up notes that hopefully will answer some questions for those interested:

Surely its much TOO LOUD to use inside! Nope, actually some of the other traditional vacuums are louder.
The cord is way TOO SHORT! True, it could be longer, but the goal with this project was to make it both cheap and easy. If someone wants to add longer cords by opening up the vacuum to wire in a longer cord or use a longer cord for the power nozzle (they are available) or even simply adding two extension cords onto the ends of what I show here, that's fine, but I was trying to keep the project simple for a broader audience, and really its not that big of an issue to have to move the plugs a few times while cleaning.
Wait, how is the power nozzle controlled, is it on ALL THE TIME when plugged in? No, there is a trigger switch on the handle to turn it ON/OFF. (Good question though, whoever that was!)
Oh and regarding the $3000 price tag on the Title Image, if anyone is questioning that; Check the prices on Rexair or Kirbys website. That's NOT an exaggeration!

Introduction: Ultimate (On a Budget) Home Vacuum