Share your Shredder motor experience

Hello Everyone
Many people around the forum has seen @lyricalpolymath ‘s “almost definitive guide on motors” and I’m sure many of you found the information collected on that topic useful on the initial stage of your Shredder build project.

My intention on this topic is to collect information about success/failure stories with the motors you tested on your shredder, along with specs about the motor you tested.

For instance, I read that @seyn-sustainableenergyyouthnetwork tried a monophasic 3HP motor on the shredder and it clogged very often. @lyricalpolymath also reported that monophasic motors are not good enough for the shredder regardless of their HP.
My aim is to collect a concise database of real-life machine builder stories about their experience building the shredder and which motors they used.

I’ll start:

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Owner: @xxxolivierxxx
Motor type: Monophasic
Voltage: 110v/220v
RPM: 1430/1710
Reducer: 1:30~
Output RPM: 56/60
Power: 1/2HP
Result: Failure
Details: The motor is simply not strong enough to shred any type of plastic. I even added a reverse switch to see if that would help but it was just a waste of time/money.
Here’s a topic I made about my Shredder: http://onearmy.world/community/forums/topic/my-shredder/
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Owner: @flo-2
Motor type: Monophasic
Voltage: 230v
RPM: 1400 rpm
Reducer: 1:25
Output RPM: 56
Power: 2.2kW
Result: Success
Details: Weakest point is the coupling, turns freely when load is too much. I have got around 280Nm and thats enough for most things to shred. Only very thick industrial plastic crates create problems.
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Owner: @baas
Motor type: triphase
Voltage: 230v – 400v
RPM: 2280
Power: 2.2kW (± 2,5 HP)
Reducer: 1:49
Output RPM: 46.5
Result: Success.
Details: I was lucky enough that a friend gave me a relais etc for free to convert the triphase motor to 230v without loosing power. But its expansive.
Also i added a thick heavy hex coupling with keyways. It looks way too big but according to the formula its needed.
Its really strong. It only clogs shortly when the shredderbox is filled with plastic particles.
Watch Ed shredding here ;D

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Owner: @kettlekekkers
Motor type: mono-phase
Voltage: 230/40v AC
RPM: about 2500
Power: 2.8kw
Reducer: inline planetary/comes with motor
Output RPM:45’ish
Output N.m; 500’ish
Result: Success. very good
Details: cheap and easy to use and apply to assembly.
shreds up to 3mm thick PP or HDPE as far as I’ve tested, compressed milk cartons could be considered more like 5/6mm thick.
electronics easy to understand and reassemble
when clogging occurs, its easy to revers with the already provided switch.
Disadvantages: its very loud! and has a 36.5mm shaft output , no choice.
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Owner: anne-barbier

Type: 3 phase
Voltage: 230v
RPM: 1440 rpm
Reducer: 1:20 , SITI – Service Class 1
Output RPM: 72
Power: 4kW
Inverter: 4kw
Quality: Low, I assume a proper ABB motor can do magic here
Result: fail EDIT: After grinding the shredder blades to a 30° cutting angle, the result is a success (read further on this thread for more details)

Video: - YouTube
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Owner: @stoli
Motor type: single phase
Voltage: 220HP: 3 (2.4 @80%)
RPM: 1740
Reducer: Worm gear 60:1
RPM:29
Output calculations based on 80% motor and 75% Gearbox :325 Ft/Lbs (440 NM)
Result: Success
Details: Good RPM, very strong. Rarely needs to reverse.Built with (2) 4″ pulleys power to drive train so the belt can slip to save the mechanics if it does bind. Flakes in picture is using a 5mm hole sieve.

Hey @xxxolivierxxx, didn’t you since build a better shredder? Power:2HP rpm:??? result:???

It would be useful to have as many reference points as possible. The ‘standard’ PP shredder: 2kW, 70 rpm, result: unstoppable.

It’s not just about the motor (and whether it’s single or 3 phase). The choice of gearbox is very important too. 70rpm is not ideal for every motor.

@mogambo: no! you need 2+ Kw and the reducer. it’s hard to find such motors on ebay. our trader wants 359e for all inkl., before tax and transport.

Hi! I found a cheap motor online, could you let me know if this could be fit for the shredder?

https://www.ebay.de/itm/Elektromotor-Drehstrommotor-Kompressor-Motor-Asynchronmotor-B14-0-37KW-0-18KW-/254098946752?var=

Thanks in advance guys! I am just starting and getting all the knowledge from you I can!

@mohammede335 if you can only get rigid couplers then its fine, they will work, although its not recommended since you can damage your motor, reducer, or even the shredder. On regards of shredding at 1500rps, that is a really bad Idea. At that speed, the friction will cause the plastic to melt. It might work but you would need a different shredder design

Hi…I’ve seen lots use a rigid coupler held on with screws on a plain shaft, this is bad for two reasons, it will slip when overloaded and the screws will tear up the shaft, and unless very accurately aligned it will cause binding.

seo specialist

Hello everyone, what would be your engine configuration powerful/torque to build a huge shredder which can treat about 50kg per hour ??
Thanks

ok, thank you xxxolivierxxx. that’s explain a lot…

@halimwidyakusuma a double shaft shredder should be capable or shredding using a less powerful motor but theoretically the output should be slower because of the smaller teeth (assuming we are talking of same-size shredders). Precious Plastic only has a single shaft shredder so we can’t speak on regards of other shredder designs, but there are plently of videos on youtube that you can use to compare both shredder designs

@sheffieldcompany thanks so much for the explanations, it’s always good to see real competence bind to the cause.

@xxxolivierxxx. Yes VFDs are quite versatile for regulating speed easily and braking a motor from 3200rpm to zero rpm in 2 seconds etc. I don’t think you really need a VFD for shredding. Just reversing capabilities and even that is not needed. Just unplug the unit and rotate it by hand backwards. Shredding is a complete science. There are several companies that only focus on that. To think the shredder will never jam is not realistic. Vecoplan, Rapid granulator and others only focus on shredding. Neither of their websites guarantees no jamming. I really suggest everyone focus on the capabilities to shred not the speed of completing the activity. You still need to make something and shredded plastic is not really a thing.

Hello All. Here is the most clearly defined way of describing phase converters.
Static phase converters are a startup device for three phase motors on single phase power.

Static phase converters operate the three phase motor they are connected to on single phase. The static phase converter does not actually generate three phase power continuously as a does a rotary phase converter, but only long enough for the motor to start up. Once the three phase motor has started up the static phase converter circuitry disconnects itself and the motor continues to run on single-phase power but because only two of three windings receive power during running, horsepower output is reduced down to between two-thirds and one-half the rated motor horse power. A 15 HP motor will start with the power of a 15 but run as a 7.5 for example.

The high starting torque with reduced running power is an important factor when considering the use of a static phase converter. In some situations this can work out very well but the static converter does have limitations. Static phase converters are not well suited for machines that operate continuously close to the maximum rated horsepower of the motor that operates them. This type of continuous full power loading can be seen in equipment such as water pumps. The pump is sized to use all of the motor’s power while pumping. Lathes are another good example of this need for full power. Although the static phase converter appears to work well on lathes in the slower speeds, in the higher speeds the converter is able to start the lathe turning but the lack of rated horsepower makes these higher speed settings useless. A TEMCO Rotary Phase Converter is best suited for this application.
Taken from http://www.phaseconverter.com/what-is-static.html
Now study up and then move forward!

@plastikfantastik How many HP/KW does your motor have?

Mine is a 5HP 220v triphase motor converted to 220v Monophase using capacitors. If my math is correct, I should lose around 1HP in strenght. At 4HP I should have around 569.64n.m of torque which is plenty. I understand that too much plastic could jam the shredder, but I also think a better shredder design might help overcome the jamming issue. I took a jug of milk which is made of soft HDPE, and cut the gallon in 4 pieces. Adding 3 of those pieces into the shredder jams it which is a little dissapointing. I’m planning to try guenter’s suggestion of sharping the blades a little but I fear it might reduce the shredding ability

xxxolivierxxx I have been looking at youtube videos of different shredders and even the bigger ones will jam if there is too much material being put through. I watched each of the videos for this very thing and they all did it.
Thought this fact might be of interest. I think the expectation of no jamming is a bit unrealistic.
owner plastikfantastik
Motor type: single phase
Voltage: 240
RPM: 1440
Reducer: Worm gear 20:1
RPM:72
jamms a bit but ok when put into reverse it corrects easily

@sheffieldcompany I’m still learning about triphase motors and how they work, but I had the same question. In theory, VFDs are the same as using capacitors but with the added benefit that you can regulate rotation speed and have a unified control system.

Guys. This is not correct regarding capacitors and motor sizing. Go to Grizzly.com and other websites. They sell static phase converters up to 10hp and rotary phase converters up to 75 hp. The reason you don’t see/use capacitors over 5hp is because rotary is more economical using smaller capacitors to create the third phase. I used a 15hp rotary for 5 years for a yag laser engraving machine. No problems. A VFD is basically a bunch of electronic controlled capacitors. You can “create” your own phase converter” as long as all output phases are within 5% (exact same is best but nearly impossible) of one another and 10% of nominal voltage it should work just fine. Please educate yourselves. There is a lot of info on the internet regarding rotary phase converters. Best of luck to all.
PS. Currently I’m using 220v single phase 15.3 amp input VFD and getting 220v 3 phase 7.0 amp output. it’s still just capacitors only!

@xxxolivierxxx, yup, that’s an original, it has always the orange sticker and a potentiometer, anything else is a crap copy. i had recently one of those cheap clones, it comes with 1/10 of the parameters only, and i burned it up right away 🙂
also, don’t forget, with the right reducer, you are only using 30% – 60 % of what the motor/inverter provides (one shredder with one extrusion simultaneously). that’s why, dont buy second hand reducers 🙂

@xxxolivierxxx, ack, just to let you know, the capacitor trick isn’t recommended for anything above 3kw! i speak out of experience and i’ve got this told from experts as well (they will laugh at you for even mentioning it), you can however get the  best out of it (always) and go the usual path by using a inverter just, one for 4kw = 220 euro, deal with it 🙂 also, don’t buy the cheapest, you get way more security and long life by buying recommended inverters only! (hy or omron)

@anne-barbier I have a 5hp motoreducer that used to be 220v triphase and was converted to 220v monophase using capacitors. In my calculations, the power loss is around 0.75hp which still leaves me with plenty of shredding torque, but the shredder still jams often. I’ll try filing down the blades and see what happens.

@baas Would you mind sharing a pic of what your 220v motor conversion looks like?

@xxxolivierxxx : no, the machine is now at the client’s shop, i am visiting them in a week for inspection. i will let you know :-). but as far i remember, the blades did a real good job, i tried slices of 4cm PVC pipes, no problem! i couldn’t even get it  jammed anymore when throwing 6kg of already shredded plastic chips into the hopper. next time when i get the machine back for adding upgrades, i will install an Raspberry PI to collect data from the inverter 🙂 i believe however that the magic comes from the reducer which was easy to turn with the hand which wasn’t the case with all the reducers i tried at the scrap yard.