Run Extruder & Shredder with one motor

I’m playing with the idea of using one motor & reducer for both machines: the shredder & extruder. Currently I have a 5HP|3Phase – 4Kw motor and a 1:21 reducer in place, running with 4Kw VFD.

Somehow it seems obvious to extend the drive shaft for the shredder to run the drill, with some coupling.

Does this makes sense, did anyone try that yet? According to the experiences here reported in the forums, it seems I could run 2 shredders and 2 extruders with that motor. It’s a long setup  but I like the idea, it’s like these old steam powered workshops where one motor powers everything via belts & pulleys.

Thanks in advance,

Hello @mc007
Yes you can, but need to be a careful and preheat the extruder for at least 10min before any use or you might break your extruder.
Look at this for more info:


@fabirihotmail-com I used DOM seamless tube with 1″ ID and a 1″ Auger bit. I’ve used both .188 and .120 wall tube, .188 needs to be turned down a bit for NPT threads to be cut, .120 is a bit small and threads are flat but it works.  Since you are in Europe, you should be able to source the metric sizes specified in the original design.
DOM (Drawn Over Mandrel) tube is often used for racing roll cages, so if you are having a hard time finding it maybe you should check a local shop that builds race cars or supplies race car builders.

@justinc could you please tell me the diameter of the tube and screw that you use? are the same or have some difference , could you also please tell which kind of tube and screw you use?

hey @justin,
i couldn’t reach you anymore through the bazar, however:
i changed the product description, linking to the facebook pictures, for now. I couldn’t find the source of the machine, I am happy to link to your version/link :-). Anyhow, as soon my tests are over, I am opening a Github repo for this combo. I added a clutch like coupling and changed a couple of other things. Btw. there is only one rope here, us or nobody 🙂

ps: in case you didn’t notice: we’re doing this for free, on a non-profit base, exactly as the mission needs….

Hey Justin,
thanks a lot for popping up here! I didn’t assemble yet this build but my idea was to add a clutch like coupling before the extruder, in hope that the user can react in critical situations. Not sure yet this actually makes sense.

I thought both machines need around 70 RPM (?) but I hope that the potentiometer on the VFD (controlled by an external outlet) should be enough to control the speed. I’m not sure how much speed adjustment a user needs but the range of 30% +/- for 70 RPM speed should be fine, though. Also enabling  forward/backward through the terminal should solve clogging in the shredder.

I guess I have to make some chips first to see where the trouble is 🙂 Good to know already about the stalling in the extrusion, so big thanks to you!

Generally speaking, the concept of running both machines with one drive unit seems very practical and more economical than using two separate machines. The issue is that both machines have different power and speed requirements, so if you are not careful you can do some damage.

I built the machine in the photos above and am currently testing and developing it.  The motor is spec’d out for the shredder and intended to put out significant torque needed to chop up plastic, however the extruder doesn’t need all that power and the Precious Plastic design did not have it in mind.  Therefore if there is any binding in the extrusion barrel, all torque from the shredder motor can break the auger and bend the frame.

So basically, the concept is good, but if you don’t use the tool properly you can do some damage.  Currently working to find the right balance of durability and performance.

Thanks Oliver, I try my luck to reproduce this. I hope I can find some more existing material but I guess I go with some Arduino compatible hardware, in hope to get a ‘handle’ on a VFD and some out-of-the-box temp. controller that way 🙂

kind regards,

@mc007 that’s not my shredder, it belong to the person who posted it on facebook.
However, the controller board in there is pretty simple, it’s just 2 PID controllers used to monitor the temperatures of the heating elements through a K-type thermocouple. The reason there are 2 of them is because one regulates the temperature of the heating bands close to the end of the barrel, and the other regulates the temperature of the heating bands around the middle of the barrel. They are both configured with around a 30-40 degrees of difference, the heating bands near the end of the barrel being hotter to facilitate the flow of the plastic to through the nozzle. The switch in the middle is just an On/Off switch.

@oliver: could you please enlighten us a little with that freaking awesome controller board you have there ? I’m puzzled about what it all does….

holy moly, that’s an awesome shredder. If you don’t mind, I attached the pictures here. That deserves definitely an ‘precious award of the month’ !

So yes, thanks. You just gave me green light to do it just. Eventually I build something to manually couple the main drive shaft to the shredder & extruder shaft…not sure how this could work.

thanks again,