Making a Rotational Casting Machine with a CNC

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A rotational casting machine, in case you didn’t know, is a device which can be used to make hollow casts. (Think of those hollow Easter bunnies) I made mine by first designing it in Google Sketchup and then cutting out the parts with my CNC machine. All I had to do then was just put it together.

I don’t have a full step by step write up of this project, but using the Sketchup model, CamBam files, video, and pictures, you should be able to figure out how it goes together without much trouble.


Here’s a video of the assembled machine. This design is smaller than the others I’ve seen on the net. I don’t need to make casts which are especially big, so I decided to make this machine a convenient size.

Materials and Hardware

This rotational casting machine can be built from just a few dollars worth of material. In fact, mine was made from scrap, so it was basically free. The gears were made out of 1/2″ MDF (although 3/4″ would also work). The stand was made out of 3/4″ MDF and sits on top of a 2″x6″. The square “frame” is made out of 3/4″ OSB.

As far as hardware is concerned, I mostly used 1/4″ threaded rod which I cut to whatever length I needed with an angle grinder. I also used 1/4″ nuts along with washers.

The exact types of materials and hardware isn’t crucial, so, if you want to make one of your own, you can improvise with whatever you happen to have.


Here are the CamBam files for this machine. Rotational Casting Machine
I used a 1/64″ router bit to cut out the gears and a 1/4″ bit for the rest. You might find it easier to just use a 1/8″ bit for everything. You can, of course, change the bit size in CamBam.

Here is the Sketchup model too so that you can use it to see where everything is supposed to go. rotational casting


Here’s a picture of my CNC cutting out a couple of the parts.

CNC Made Rotational_Casting_Machine

Next, we have a picture of the parts that the CNC just made laid out on display.


Here’s the fully assembled machine. Notice how it’s bolted to a 2″x6″.


Here’s a picture of the gears.



Next, here’s a close up of where the gears mesh at a 90 degree angle.


Finally, here’s yet another picture of the gears. You can see that the one at the top on the right side is a little crooked. It works ok though, so I don’t worry about it. I had a difficult time getting that one exactly where it needed to be.


If you do try to build one of these machines, make sure that the gears are in the right spot before you drill any holes. These gears shouldn’t be put together tightly. If they are, the gears which mesh at a 90 degree angle won’t be able to reach each other.

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