(Almost) Definitive guide on Motors (WIP)

Hey everybody,
I’ve summarised a bit of the various posts on the motors that can be found around in this forum, and wrote this Google Doc that you can all see, comment and edit.

check it out and help complete it if you can / want.
The idea is to start preparing a simple, clean doc about the motors to expand the awesome specsheets that @davehakkens produced.

let’s keep the messy discussion here in the forum or as comments in the doc and there put only the final results.

It would be great to put some examples, with the pictures of the label of the working motors that people are using.
@davehakkens could you post a pic of yours or is it all painted in grey? 😉

If anyone here has made the machines and they are working, please post images of the nameplate of your motor and what the pros and cons you see in them

this doc builds on many other posts and contributions that you can find in these forums:
Shredder Motor
Realistic Cost Shredder
All posts that name “motor”

Let me know what you think
thanks to all

ps I’m in Malaga, Spain too if any other spaniard wants to hook up. We also found some providers we can talk about and if we order all together the pieces maybe we get a discount 😉

One step closer to be able to use a cheap washing machine motor for the precious plastics machines

I’ve found this awesome Gear Generator that makes it easier to produce our own Reducer gearbox

check this example: These parameters convert a 1400 rpm to 70 rpm

The current code has a limitation to 360 rpm max, but if you open the console
(View > Developer > Javascript Console in Chrome) and paste this function:

function getRPMfix() { return fixInput( Number( $("#RPM").val() ), setRPM, RPM, -1400, 1400 ); }

It will allow you to input 1400 RPM

Anyone here in the forum has mechanical engineering experience and sees any problem with lasercutting this, building a box similar to the shredder box and hooking this up to a washing machine’s motor?

Will the torque of a washing machine still be enough at 70rpm?


@eltonmcj they look pretty good, although finding the gear reducer will be the most difficult part.

Hello everyone,

can you guide me on the purchase of a motor winch, I have an online sales site that sells them between 100 and 200 euro, however I have read on various posts that an adapted motor with numbers of laps to make it obsolete, if you could orient me it would be cool.Thank you for your help.

here is the links : https://www.manomano.fr/cat/moteur+treuil


Thanks for your reply, I’ll head to the recource section.

@colleen, really hard to say without pictures of the motor plate and the gearing. You want a final speed of 40 – 70 RPM and a torque between 220 (still jams) and 500 Nm. Going higher could eventually destroy the shredder blades. Here are number of tools in the ‘Resource’ section.

Just wondering if anyone knows if a treadmill motor would be a suitable application for the shredder. It has a 2kw motor. I don’t know if a treadmill uses a gear box but it has variable speeds. Any advice would be very appreciated.
Thanks Colleen

@andrevieira4, should be fine. it’s a little too fast for some plastics but with an inverter you can slow it down by max. 50%; otherwise motor running hot. but i’d be you i’d open gearbox and motor; not sure what happened to it but it didn’t receive much love.

That is a high quality motor made by Emerson used to run centrifugal pumps. It is close coupled and fan cooled rated for 40C. They use these a lot in agricultural situations. Btw, going from single phase to three phase is called a converter, an inverter changes DC to AC.

should be fine, most heavier duty motors I’ve came along were around 1500 RPM, I can’t tell why but may be because they run more steady and longer; especially considering the bearings have to swallow whopping 3000 RPM it makes sense. More or less you need 50 – 70 RPM for the v3 shredder; you would need at least a 1:40 reducer, 1:60 would be better (more torque) but slower. From what I’ve read it’s not ideal for the gearbox to have so much reduction because of the friction and energy loss it creates. If you don’t have 3 phase, you need also an inverter (which gives you also over torque protection), cost around 120 Euro new, 80 second hand. Here’s a collection of useful  calculators (collected from the forum here).


Right, I’ve got a motor running at 4,000 RPM, 2.4 kW, 240v, 2 pole. From what I can tell I’ll need at least a 50:1 gearbox, if not a 70:1.

If you get  wood chopper just be aware that there are two types. The type you want includes a gearbox which slows the blade down so it slowly grinds the wood. There is another type which has a very fast spinning disc with blades on it. The fast type doesn’t work well with plastic – it makes a huge noise and takes a very long time; eventually you end up with a plastic dust which is not very good for several reasons (hard to collect, blows around, colours get so well mixed that everything you make is brown).

Thanks for the reply and the tip.
I was looking for a wood chopper. Looks like a good option. I think I will go for that!.

Single phase shredding can work. The torque can be high enough if you are willing to accept a slower speed. Look at this thread: http://onearmy.world/community/forums/topic/shredder-bulid-idea/
I’m working on a shredder using the same basis, but it’s not finished yet.

Well, for shredding failed PLA prints, there is always this option

you can use single phase motors but its not recommended. to run a 3 phase motor (2 + Kw), you need a VFD (3Kw = 120 Euro) which also provides more control and fine tuning as well safety (fault/over torque protection) ; see buying guide here.

I’m starting work on the extrusion machine. I’ve been searching these forums for some info on what sorts of motor work well for this; there are loads of posts about the shredder motor but very little I can find on the extrusion motor – can anyone point me to some good threads on this or put info here (this seems like the best place for it (a sticky thread on motors, but the google doc is almost all about the shredder).
Ideally I’d like some tips on what sort of equipment has the correct type of motors and gearboxes in them; or is it best to buy a new motor and gearbox set?
This thread on the shredder motor is great:

shredder build IDEA

Is there anything similar out there for the extrusion machine?

@unratonloco, there is plenty on youtube about, just search for ‘3 phase motor’ or variants of it: ‘3 phase motor wiring’. You can go also with trial and error, also take into account the kind of connection: delta or star, google gives you lots of results about ‘3 phase motor delta star connection’, images & videos. there is not much to it at the end.

I am getting some issues trying to get conected my three phases motor, I was wondering if I need to be worried about what kind of conection i need to start ande wich one after starting. May be someone has a diagram how to wire a threephases motor correctly or a tip that can share.

thanks for all

This is amazing @lyricalpolymath! thanks for creating this it has seriously helped!