Customizable Cyclone Separator (with Onshape Model and FeatureScript)

A not so successful build to help clean up, after the kids are done playing ;) But it is a cyclone generating FeatureScript nonetheless.

Introduction / The Story

My son loves construction vehicles. Especially his ride-on excavator. And we use a bunch of Bruder, Lena, Wader and Lego Technic vehicles to play.
Since empty excavator buckets are boring, Korkschrot / cork granulate makes up for a great wood-floor-compatible dirt alternative.

10L of the cork granulate is a bunch. A grain size of 0.5 - 3mm made sense to me, but it contained a bunch of powder as well.

Also, while plying, granulate breaks down. Plus, sweeping everything up adds some hair and dust.

The Cyclone

I knew cyclone separators were used in wood workshops, but I had not used or seen one in action. I checked out the available options of finished models but none really matched my purpose.
So I checked out customizable options. 

Unfortunately, both the above-mentioned OpenSCAD scripts did not match my plan of using a wide-neck drinking bottle or washing machine detergent bottle, nor did they fit my Dyson V12 vacuum.
Unfortunately both did not even produce a manifold body with my parameters. Attempts to fix it would still require converting to STEP file in FreeCAD before export it as a solid. To have any chance of customizing it in Onshape.

The FeatureScript

So I first looked into remixing the OpenSCAD scripts but soon realized the inefficiency of the workflow. It was time consuming, error prone and editing a mesh in Onshape is really impractical.
AI helped refactor the NTdesign SCAD version into an Onshape FeatureScript, while adding a bunch of additional parameters and making some improvements.
The resulting parametric model can easily be modified. I did to that in a separate Onshape model, make it sturdier, and  use it as a reference to create new adaptors. For a detergent bottle, a suction hose and as vacuum connector.

Experimentation

I did a lot of prints. Long cone, short cone, different body widths and immersion tube width and length. All in order to tune the cut-point of the cyclone (which particle size goes where) and dumping into the bottle without jams. 

The result, unfortunately, is not impressive 😂

I think the small cyclone spins too fast. It probably requires more diameter or a much higher body. But it still works a bit and makes it easier to pick up the granulate.

Custom Parts

Through an adaptor the cyclone directly mounts to a Dyson V12.
The dyson adapter has an OD of 34.5 mm. With two additional layers of electrical tape, it creates a good friction fit and air tight connection.

It is critical that the container, whichever it will be, is connected to the cyclone absolutely airtight.
If air leaks past the bottle into the cone, it creates a counter spiral preventing the granulate to drop out of the hopper and into the bottle. 

To get this tight, the best solution was to use a universal and really wide cyclone neck with a generic thread. In it, a TPU plug holds the generic thread on the outside and the bottle thread on the inside.

For all the other connections air leaks are not critical. Drag would only reduce the suction power, which seems to make not much of a difference at all.

The Test

The box of cork in the pictures, about 8 Liters, was sucked up.
I tried to prove that it works, but I’m not convinced. And it did not get small cork particles I wanted it to catch, as well.

Dimensions of the provided Models

If you do not want to use the FeatureScript, which I highly suggest, here are the dimensions of the provided STL's:

Cyclone

• Body OD: 84 mm

• Bottle thread diameter: approx. 28 mm

• Inlet ID: 20 mm

• Cone length: 40 mm/80 mm

• Vacuum outlet ID: 35 mm
  

Dyson Adapter:

• ID: 28 mm

• OD: 34.5 mm

Because a wider vacuum outlet is required for the cut-point, an additional reducer is added in between the vacuum and the cyclone, to reduce the vacuum outlet ID to the Dyson ID.

Printing

I used PETG to make it more elastic than brittle.
You do not need to support the inlet, but it makes the print much cleaner. I forgot it on multiple prints and the mess was easily cleanable with some filing.
Make sure the thread does not get supported, to not end up with a cyclone full of support material. The thread is designed to print without supports.

Use at least 3 walls and 5 top and bottom layers. 

Set support threshold to 20, so the thread is not supported. Only the inlet should be with tree supports.

FeatureScript and Models

Please go ahead and download any or all files here, so I get some credit (thanks), but then head over to Onshape and create the cyclone you really need!
Or let me know in the comments, if you need specific parameters and I try to help you out.

Especially let me know if there are errors caused by parameter changes. I did not test much other dimensions but these small ones. So the script it could easily break going bigger... 

You can find the FeatureScript for the base cyclone shape generation here:
Onshape FeatureScript - Customizable Cyclone Separator Script

And my Onshape model, with additional parts, here:
Onshape Model - Dyson V12 Korkschrot Cyclone Separator

I added a modified OpenSCAD variant as well. I would not recommend using it, but it should generate a valid body.