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Share your Shredder motor experience

This topic contains 77 replies, has 24 voices, and was last updated by  Anonymous 7 months ago.

9
Olivier xxxolivierxxx

Share your Shredder motor experience

16/11/2017 at 03:35

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:

#######################################################################
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: https://davehakkens.nl/community/forums/topic/my-shredder/
#######################################################################
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.
#######################################################################
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

#######################################################################
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.
#######################################################################
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: https://www.youtube.com/watch?v=4SNiDleTKac
#######################################################################

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.

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dedicated
23/06/2018 at 15:53
1

@sonik, this is in theory, as you can see in a lot of videos, many times bottles jump from the blades due to the high speed, in add up must consider the dead times between a bottle and the next, so maybe a 70 rpm will probably produce more kg/hour plastic than a 17 rpm but I think no more than twice. The pp shredder run well at 28 rpm, about the Filamaker that run at 17 rpm it has 2 axes so when it takes a bottle it shred all without bottles jumping. By the way I prefer a 20 kg shredder machine that I can transport and use everywhere, with sunpower or windpower instead of a 70 or more kg machine that need high power energy. what do yo think about it? 😉

dedicated
23/06/2018 at 10:08
1

@fabirihotmail-com Concerning power consumption: 17 rpm will produce more or less 25% of a 70 rpm shredder, Which means that you shredder will run 4 x longer to produce the same amount of plastic.
And of course don’t forget the cosinus phi of your motor for real calculations.

warrior
22/06/2018 at 07:33
1

@fabirihotmail-com 0.37kw at 17rpm should give you 207.83N.m.
Theoretically that should work, but is still far away from the minimum 300n.m recommended to shred plastic

dedicated
22/06/2018 at 06:32
1

Used a 750w monophase 4 pole Motor with finaln28 rpm and it doesn’t work, so with a 1100w 28 Rpm it will work for sure or it’s possible to use a 750w 14 or 17 rpm and it will have enough torque to work.
At the moment I change my mind And I will use the same shredder of Olivier with a 250w motor and 17 rpm, it has more torque than the one he was using (370w 35 rpm?) If it doesn’t work I will use a 370w 17 rpm and recycle the 250w for the extruder.

warrior
11/04/2018 at 10:30
1

Hello @cecilio
Yes, it has more than enough torque so it won’t have any problem shredding any plastic. The RPMs are a little high, ideally we would like to keep them close to 60RPM because if the shredder spins too fast it tends to make plastic fly away, but you can probably work around that problem by making a square hopper and push the plastic into the shredder with a cover with a handle, like this one https://bazar.preciousplastic.com/listings/548935-star-usa-star-hopper-for-shredder

starter
09/04/2018 at 01:31
1

hola
I have a 5.5kW 3 phases motor with a gear reductor to +/-80 rpm, complete with the switch box. It comes from an oil extrudder.
Do u think it will fit to a shredder I made?
saludos
cecilio

Attachments:
helper
28/12/2017 at 22:32
1

thanks @wess !
I’m committed to 3/4 for now. My gearbox shaft is 1 3/8″ so I’ll be starting a new shredder from scratch if I go that route. I too will be slowing down the RPM from 60 to 40-ish if I get to a rebuild someday.

starter
28/12/2017 at 14:49
1

To select the shaft size, I just went with whatever size the gearbox uses. You could do a calculation to determine the minimum shaft size, but I went this route because coupling the gearbox to the shredder shaft being equal size is a lot easier for a variety of reasons.

One thing I will note, it will NOT hurt to oversize the gearbox/motor in terms of torque.

helper
28/12/2017 at 05:23
1

Also, It might be helpful to know what kind of overload protection people are using.

helper
28/12/2017 at 05:17
1

@wess – Is there a method you use to determine shaft size? I’m all the way down to 3/4″. I suspect this is going to be too small in the long run.
I’m about to ditch my sheer pin all together… and I’d like to know what my next weak link is! I’m guessing it’s the spider coupling insert.

helper
19/12/2017 at 19:15
1

I would love to know more about the coupling you guys are using.
I’ve got a 3HP Single phase motor, with a reduction to 60 RPM. I connected my gearbox to the shredder with a heavy spider coupling. I didn’t get my shredder shaft keyed – so I put in a sheer pin on the shredder side.

I haven’t figured torque yet, but we’re snapping sheer pins all the time.

My shredder has a 12″ opening – so quite a bit more teeth to bite. However, my experience shows it’s when the milk cartons, PET bottles, etc, fold over on themselves – even it’s only over couple of teeth – that it’s hardest on the shredder.

warrior
19/11/2017 at 15:05
1

Adam @kettlekekkers, You seem to be way ahead in terms of power and torque. Does it ever jam? And what happens if it does? It looks like your jaw coupling (good choice) is attached to the shredder shaft with a couple of bolts, do they go through the shaft or just tighten up against it?

warrior
18/11/2017 at 00:50
1

@xxxolivierxxx, @flo-2

Ok, I see whats going on here. Yes Olivier, 2.2kW at 56rpm would equal 375Nm, however the company that supplied the motor/gearbox quoted 280Nm.

2.2kW is the mechanical output power of the motor. No gearbox is 100% efficient so some of this power will be lost. 280 is almost exactly 75% of 375, so it looks like they have used a figure of 75% for the efficiency of this motor/gearbox combo. Sounds reasonable as it’s probably a worm type gearbox.

warrior
17/11/2017 at 13:40
1

@flo-2

Your experience fits much better with what I would expect, but did you measure 280Nm or calculate it? It should be higher.

I agree the coupling is a weak point and overlooked by many people. 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. The best solution is a keyway as @xxxolivierxxx mentioned, onto which a flexible coupling is mounted. Though there is then a danger that if you use too big a motor you might actually break the shaft. (I think 2.2kW is really the maximum sensible size)

The binding issue with a rigid coupling and a capacitor-run motor could be another reason SEYN had a poor experience with a motor that should have been more than powerful enough.

warrior
16/11/2017 at 20:51
1

That’s interesting, do you know what reduction/rpm they had?

starter
22/02/2019 at 17:17
0

@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.

starter
22/02/2019 at 16:59
0

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!

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