Picture of K'Nex Roto-moulding machine
One of the biggest problems with building your own DIY equipment is the space that it takes up. If you happen to live in a small space and don't have a workshop to keep your kit in, it can very quickly become overwhelming.
A descent roto-moulding (or roto-casting depending on your terminology) machine is quite a bulky thing.  Add to that the limited space that you have as a student (or freelance product designer) and you have a dilemma - you would like the equipment, but need it to be stored in as small a space as possible.

The solution to all of these problems comes with K'NEX.  This child's construction toy is lightweight, strong, reasonably cheap and best of all completely adaptable for different purposes.  These instructions will show you how to build a fully functional machine with a big enough space for descent models and projects.
This is prefect for small plastic casting, but also for more 'family friendly' projects such as Easter egg making (more on that later)...


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Step 1: Counter-balance (x1)

Picture of Counter-balance (x1)
To begin with you need to construct the inside frame for the roto-moulder.
This can be done using normal purple connectors and white sticks. You also need to add some wheels to this part to add ballast.

Step 2: Motor (x1)

Picture of Motor (x1)
For the opposite side of the inside frame, you need to insert a motor (to do the first set of rotation). This is why you needed the wheels as counter ballast in step 1.

Step 3: Rigging (x2)

Picture of Rigging (x2)
You need to build two of these parts. These connect the motor part and the counter balance part together together to complete the inside frame. These parts can be joined using the numbers indicated.

Step 4: Pivot & motor (x2)

Picture of Pivot & motor (x2)
The next stage is to build the support structure for the inside frame. This allows the inside frame to rotate (thus spinning the material you are moulding around inside the mould).

Step 5: Main body one (x2)

Picture of Main body one (x2)
These pieces make the main bulk of the support, raising the inside frame off the ground enough for it to rotate.
jbrecken2 years ago
You could use this thing for training minature astronauts.
-DOUG-3 years ago
Am I missing something? How do you melt the plastic?
This is great. I love when people make cool & practical things (ie NOT guns or ball machines) with K'nex. And these schematics are amazing! What did you use?
HRhV (author)  plysaxaphone3 years ago
Thanks! Mainly Photoshop to just clean up the images.. There are a few K'Nex CAD programs out there, but they generally can't hand the complexity that this machine has.
Sorunome3 years ago
bjarne963 years ago
codongolev3 years ago
congratulations on making the first k'nex project in a long time that might actually be featured. this thing is pretty cool.